On the Theory of Lubrication and Its Application to Mr.Beauchamp Tower's Experiments, Including an E
弹性流体动力润滑
(3)道森-希金森最小油膜厚度公式
hmin
2.65
0.54 (0u )
E W '0.03
R 0.7 写为：
G U 0.54 0.7 H min 2.65 W 0.13
道森一希金森公式和格鲁宾公式合用旳范围基本 一样。在下列任一条件下来使用它们将受到限制，不 然精度就会明显降低。
五、能量方程
8.4 线接触弹流润滑问题旳分析与讨论
8.4.1 线接触等温全膜弹流旳近似解—格鲁宾理论
格鲁宾公式（Грубин）
84
h0
1.95 0u
11
1
R11
W 11
E '
格鲁宾公式是最早得出旳与实际接近旳弹性流体动力润滑最小油 膜厚度计算公式。是用解析法及采用前面所述旳模型和某些设定推导 出来旳。
线接触等温全膜弹流旳数值解—道森-希金森理论
(2)压力分布和油膜形状经过广泛旳数值计算，概括 起来可得到下列旳主要结论:
①弹流经典旳压力分布和油膜形状如图所示。
②弹性变形和粘度变化旳联合效应可使承载能力大为提升。如图8.7所示，在具有 相同旳中心油膜厚度旳情况下，刚性一等粘度旳润滑状态承载能力最小;弹性一变 枯度旳润滑状态承载能力最大:弹性变形和粘压效应旳联合作用比它们单独旳效应 要大得多。换句话说，在相同旳载荷下，考虑弹性变形和粘压效应所得旳油膜厚 度远不小于按简朴旳润滑理论所得之值。
二、流体旳粘压特征
齿轮、滚动轴承、凸轮等接触表面可化为半径相当旳圆柱体接触，其等 效半径一般为20mm左右或更小，显然在赫兹接触区将产生很高旳压九流体 压力升高将造成流体枯度和密度旳增大。在很高旳压力下，密度将增大20％ ，但对弹流承裁能力不会有很大影响，而粘度却变化很大，到达若干个数量 级，在计算承载能力时必须予以考虑。液体旳压粘特征可表达为指数关系：
Ch_2_Contact Mechanics
Contact Mechanics2.2.1 I ntroductionWhile Classical Mechanics deals solely with bulk material properties Contact Mechanics deals with bulk properties that consider surface and geometrical constraints. It is in the nature of many rheological tools to probe the materials from "outside". For instance, a probe in the form of a pin in a pin-on-disk tester is brought into contact with the material of interest, measuring properties such as hardness, wear rates, etc.Geometrical effects on local elastic deformation properties have been considered as early as 1880 with the Hertzian Theory of Elastic Deformatio.1This theory relates the circular contact area of a sphere with a plane (or more general between two spheres) to the elastic deformation properties of the materials. In the theory any surface interactions such as near contact Van der Waals interactions, or contact Adhesive interactions are neglected.An improvement over the Hertzian theory was provided by Johnson et al. (around 1970) with the JKR (Johnson, Kendall, Roberts) Theory.1In the JKR-Theory the contact is considered to be adhesive. Hence the theory correlates the contact area to the elastic material properties plus the interfacial interaction strength. Due to the adhesive contact, contacts can be formed during the unloading cycle also in the negative loading (pulling) regime. Such as the Hertzian theory, the JKR solution is also restricted to elastic sphere- sphere contacts.A more involved theory (the DMT theory) also considers Van der Waals interactions outside the elastic contact regime, which give rise to an additional load. The theory simplifies to Bradley's Van der Waals model if the two surfaces are separated and significantly appart. In Bradley's model any elastic material deformations due to the effect of attractive interaction forces are neglected. Bradley's non-contact model and the JKR contact model are very special limits explained by the Tabor coefficient.Contact Mechanical Models1:Hertz: fully elastic model,JKR: fully elastic model considering adhesion in the contact zone,Bradley purely Van der Waals model with rigid spheres,DMT fully elastic, adhesive andVan der Waals model.1 Johnson, K. L. (1985) Contact Mechanics (Cambridge University Press, Cambridge)2.2.2 H ertz's Elastic Theory of ContactHertz analyzed the stresses at the contact of two elastic solids.A1, A2 … adjacent pointsO…. contact pointsee Figure next pageSource: Johnson, K. L. (1985) Contact Mechanics (Cambridge University Press, Cambridge)2.2.3 A dhesive Corrected Hertzian Theory: The JKR TheoryNo attractive adhesion forces are considered in the Hertzian theory. Adhesion forces, as depicted below, generate "negative" loading forces.2.2.4 T he Adhesive-Elastic Contact FormationThe adhesion force between two rigid spheres can be expressed as12212γγγγγπ−+=∆∆−=;R F *adhwhere ∆γ is called the "work of adhesion" per unit area. This corresponds to the Bradley model of adhesion. The elastic adhesion model (JKR) providesγπ∆−=*JKR adh R F 23, which considers adhesion over the contact area, and an elastic response of the spheres. Considering that the JKR adhesion force equation is seemingly independent of any elastic modulus, there seems to be an inconsistency if compared to the Bradley model.The apparent discrepancy was resolved by David Tabor (1977) who introduced the following parameter:()()()323231/*//*E R σγµ∆=, "Tabor Coefficient"where E * and R * are the combined curvature and modulus, respectively, and σ the characteristic atom-atom distance. This coefficient, also called the Tabor Coefficient , determines whether or not the sphere may be treated as rigid.453, 1277-1297453, 1277-1297Attention: Do not confuse the tensile stress σ(h) with σ the LJ characteristicatom-atom distance.453, 1277-1297。
工程力学专业英语阅读4
on a beam is given by
dM V dx
（1）
This equation shows that the rate of change of the bending moment is equal to the
algebraic value of the shear force, provided that a distributed load(or no load)acts on
It is demonstrated that gases are perfectly elastic.
已经证实，气体具有理想的弹性。
3、副词作定语修饰名词，译成形容词 The equations below are derived from those above. 下面的方程式是由上面的那些方程式推导出来的。
This communication system is chiefly characterized by its simplicity of operation and the ease with which it can be maintained.
这种通讯系统的主要特点是操作简单，容易维修。 2、修饰形容词的副词，由于形容词转换成名词，因而可相应 地转译成形容词
这些材料的特点是：绝缘性好，耐磨性强。
2、某些表示事物特征的形容词作表语时可将其转译成名词， 其后往往加上“性”、“度”、“体”等，带有定冠词的某些 形容词用作名词，应译成名词
The cutting tool must be strong, tough, hard, and wear resistant. 刀具必须具有足够的强度、韧性、硬度和耐磨性。
专业英语
工程力学专业
工程流体力学 (6)
Chapter4 Similitude and Dimensional Analysis
3. Viscosity has the dimensions
(a) FL-2T (b) FL-1T-1 (c) FLT-2 (d) FL2T (e) FLT2
4. Select the incorrect completion. Shear forces
(a) zero (b) one-fourth its value when cylinder was full (c) indeterminable; insufficient data (d) greater than a similar case with water as liquid (e) none of these answers
Ⅱ、Single choice questions
Chapter4 Similitude and Dimensional Analysis
1. A fluid is a substance that (a) always expands until it fills any container (b) is practically incompressible (c) cannot be subjected to shear forces (d) cannot remain at rest under action of any shear force (e) has the same shear stress at a point regardless of its motion
(a) can never occur when the fluid is at rest (b) may occur owing to cohesion when the liquid is at rest (c) depend upon molecular interchange of momentum (d) depend upon cohesive forces (e) can never occur in a frictionless fluid, regardless of its
木材科学与工程专业英语课程内部资料
Lesson 1Word and vocabularyBase on :基于State-planned:计划经济Follow the relationship between the supply and demand：遵循供求关系Resource allocation：资源分配Wood supply shortage：木材资源短缺Be used to doing ：习惯于Used to doForester :林务官，护林人Renew:更新Rehabilitation ：恢复Forest cover：森林覆盖Forest cover percent:森林覆盖率Chinese Ministry of Forestry：中国林业部Chinese forest bureau:中国林业局Production capacity:生产能力Housing ：建筑Pulp and paper：制桨造纸Fuel：薪材Domestic supply：国内供应Afforestation：绿化Sentence1 So far, China has been losing its forest resources at a rate of about 1.4 million ha/yr, or about 2.5 ha every minute. This is mainly due to indiscriminate felling, state-planned felling programs and natural disasters2 With more than one-fifth of the world’s population, China in 1988 had o nly 3%of the world’s forest cover, on 12% of the country’s land. In 2004 China had 16.7% forest cover of the land.3 Moreover, according to statistics from the Chinese Ministry of Forestry, it is estimated that per-capita consumption of forest products will rise from 0.056 m3 in 1958 to 0.2 m3 in 1990(0.28 m3 now ). The world’s average currently is 0.58 m3 per capitation and 1.0 m3 per capitation for developed countries )questionsWhat is about wood supply and demand in China ?How to solve great gaps between wood supply and demand ? Lesson2Word and vocabularyGross feature ：宏观特征定义Softwood and heartwood:软材心材Stem , trunk and bark：树干树皮Woody material：木质材料Utilization ：利用Conversion ：转化Chip and chipboard：木片碎料板Timber ,wood and lumber：木材锯材Hand lens;普通放大镜Growth increment, growth ring and growth layer：生长轮与annual ring 却别Consist of and be composed ofWoody cells 木细胞Physiological role：生理作用Patterns of distribution：分布形态Vary with：变化Longitudinally ：纵向Make up：构成Bulk体积grain ：纹理Xylem：木质部parenchyma and prosenchyma：薄壁组织和锐端细胞组织Food storage elements：食物储存组织Protoplasm：原生质Epithelial cell：分泌细胞Resin canal：树脂道Perpendicular to ：垂至于Band of tissue：带状组织Specialized for ：专司Ray tracheid：射线管胞Identification ：鉴定Pith ,xylem ,cambium , phloem and barkWood ray 定义Veneer：单板Split：裂开Cross,transverse ,radial,tangential sectionVascular cambium, initiating layerCut across：横切Result from and result inConcentric ring：同心环Interface：界面Sapwood and heartwood 区别Inner core ：内层Outer shell：外壳Designate as：定义为Durability and permeability：耐久性和渗透性Temperate climate and tropical region：温带和热带Pit membrane：纹孔膜Vessel opening and pore：管孔Sentence1.By cutting across the stem perpendicularly, a surface is exposed which is called a cross or transverse section. A radial section results from cutting longitudinally in the plane of the wood rays, from the pith to the bark. The plane which is perpendicular to the rays and tangent to the bark is called the tangential section.2. This contrast in color has physiological significance in a general way, but it is not strictly correct to designate the core as heartwood only on the basis of its darker color. A more accurate criterion for heartwood determination is the absence of living cells within the zone, and in particular, cells of ray parenchyma which remain alive far longer than the neighboring prosenchymatous elements.3.When the pores in the early wood are much larger than those formed later in the season, and when the size transition between earlywood and latewood pores is abrupt, the wood is classified as ring porous. If little or no transition in pore size exits between earlywood and latewood, the term diffuse porous is applied. Semi-ring porous or semi- diffuse are used to describe wood in which the pore patterns are not distinctly of the ring porous nor of the diffuse porous type.3 questionsHow to tell the sapwood from heartwood ?What is the difference between the growth increments and annual ring? Make a brief introduction to gross structure of wood?Make a brief introduction to three plane of wood?What are the definitions of ring porous ,diffuse porous and semi porous wood?Lesson3Word and vocabularyGross structural feature：宏观特征Previous：前述的Have origin in ：来源于Sorting and arrangement：分类与排列Light microscope ：光学显微镜Cellular composition ：细胞成分Middle lamella：胞间层Dissolve：溶解Chemical treatment：化学处理Commercial process：：商业处理Simple pit：单纹孔(纹孔腔宽度无变化）Contain：包含Thin walled ：薄壁Coniferous ：针叶材Aggregate ray：聚合木射线Longitudinal strand：纵向薄壁组织束Longitudinal tracheid：纵向管胞Imperforate cell：不穿孔细胞Polygonal ：多边形Compression wood：应压木Paper strength：纸张强度Ray tracheid ：射线管胞Margin ：边缘Bordered pits：具缘纹孔（纹孔腔宽度有变化）Dentate thickening ：锯齿状加厚Angiosperm：被子植物Vessel and pore：导管与管孔Treachery：管状的Lumen：细胞腔Extensive pit：外延纹孔Tubular：管状的Open-ended cell：两端开口的Multiple or solitaryLibriform fiber：木纤维Slit-like：裂缝状的Dural role：双重作用Vascular tracheid 维管管胞Vasicentric tracheid : 环管管胞Sentence1.These prosenchymatous elements have bordered pits that are smaller than those found in the longitudinal tracheids and which distinguish them from the ray parenchyma cells which have only simple pits.2.Individual vessel elements are tubular, open-ended cells which, when joined end-to-end, form the vessel. They are relatively thin-walled cells specialized for conduction longitudinally in the tree3.A cell type completely different in appearance from the vessel element is the libriform fiber. This type of element is thick-walled, narrow-lumened and elongated. It is adapted for strength and support rather than conduction since it has imperforate tapered ends and small, slit-like, simple pits.4.In addition to these two specialized hardwood prosenchymatous elements there are others which have features that would indicate a dual role in the living tree, involving both conduction and support3 questions1. Why is softwood more desirable for paper manufacturing than hardwood?2.How to tell the ray prosenchymatous cells from the ray parenchyma cells?3 What are the differences between the vessels and libriform fiber4 What is the distinctive treachery structure of hardwoods?5 What contribute to the lateral conduction to the neighbouring cells?Lesson four一Word and vocabulary （1）Delve into ：研究Light microscope：光学显微镜Pit and wall纹孔和细胞壁Make indentification :鉴定High resolving power：高倍Electron microscope：电子显微镜Reveal ：揭示，说明Be composed of 组成Lignin：木素Cellulose ：纤维素semi cellulose：半纤维素Layer：层Middle lamella：胞间层Microfibril：微纤丝Primary wall：初生壁Flat helix:平缓的螺旋Thicken:加厚Secondary wallLay down:沉积Consecutively:顺序地Close to 接近Make up构成Elongated :细长的Exhibit:展示Alternating:交替的Right and left handed ：右旋或左旋Parallel to 平行Cell axis:细胞轴Innermost layer ：最里面的Similar to 相似，接近于Warty layer:瘤层Linea:直线状Strand:束状Crystalline and amorphous region:结晶区与非洁净区Crystallite:微晶Short chain :短链Laterally:侧向Strength:强度Stiffness：刚度Sentence1 As the cell reaches full size, thewall is thickened by the addition ofa three-layered secondary wall laiddown from inside the cell. The layers of the secondary wall are numbered consecutively: s1 is closest to the outside primary wall, s2 makes up the bulk of the cell wall, and s3 is nearest the inside lumen of the elongated tracheid cell.2 Each microfibril consists oflinear cellulose moleculesarranged in strands which pass through phases of parallel and nonparallel order, known as crystalline and amorphous regions.3 In the crystalline regions, the moleculesare called crystallites, after the crystal like form they assume, and are oriented essentially parallel to the microfibril axis.In the amorphous regions, the cellulose molecules exhibit a lack of parallel order and there may be a higher proportion of shorter chain molecules.3 questionsWhat is the main structure of the cell wall?What about the microfibrils of the primary wallWhat about the microfibrils of s2 layer?What layer make up the bulk of the cell wall?Relationships between wood structure (gross and microscopic) and wood processing?Lesson five一Word and vocabulary （1）word and vocabulary(1)petroleum:石油Nonrenewable and renewable :可再生与非再生的Raw materials:原材料Constantly:固定的,持续的Carbon dioxide:二氧化碳Photosynthesis:光合作用Chlorophyll:叶绿素Radiant energy:辐射能Compound :复合物Organic material:有机物Extractives:抽提物Inorganic materials:无机物Calcium:钙Sodium:钠Potassium:钾Manganese:锰Trace element:微量元素Glue:胶粘剂Bind:胶合Be compared withGlass-reinforced resin:玻璃纤维Fiber glass:玻璃纤维Synthetic resin:合成树脂Nonuniformly:非均匀的Molecular weight:分子量Phenylpropane:苯丙烷Carbohydrate:碳氢化合物Serve as:用作,用于Binding agent:粘合物Dimensional change:尺寸变化Moisture content:含水率Toxicity:毒性Resistant to:抵抗的,阻止,有耐性Decay and insect attack:腐朽与虫害Thermoplastic : 热塑性的Pilable:可塑的，可弯的Glucose:葡萄糖Mineral acid:无机酸Revert:返回Hydroxyl group:羟基Reactive site反应点Derivative:衍生物Cellulose acetate:纤维素醋酸盐Swelling and shrinking :膨胀与收缩X-ray diffraction :x射线衍射Inaccessible to :不能进入Penetrate:穿透Polysaccharide:多糖Form from:形成于,产生于Simple sugar:单糖Galactose:半乳糖mannose:甘露糖xylose :木糖Arabinose:阿拉伯糖Xylan ：木聚糖Sentence1 All wood is formed from carbon dioxidewhich is taken from the air, and from water which is taken from the soil along with small amounts of dissolved minerals.2 Although composed of carbon,hydrogen, and oxygen, lignin is nota carbohydrate nor even related tothis class of compound. It is, instead, essentially phenolic in nature.3 The hydroxyl groups give cellulose itsprincipal chemical properties and are the reactive sites to which other chemical groups can be attached in the preparation of derivatives, such as cellulose acetate, The hydroxyl groups strongly attract water molecules and thus are the major cause of the swelling and shrinking of wood.4 The hemicelluloses, in contrast, areformed from a number of sugars, the most important of which are glucose, galactose, mannose, xylose, and arabinose.questions1.What are the elementscomposition of dry wood?2 What contribute to the wood strength?3 What is the natures of the lignin?4 What is the cause of woodswelling and shrinking?5 Why the composition of lignin in woodremain uncertainty?Lesson sixword and vocabulary(1)Deformation：变形Be referred to as ：称作，称为Mechanical properties 力学性质Carry：承担，负荷Strength :强度Applied load or force :施加力或作用力Resistance to deformation :抗变形Compress：压缩Distort：变形Bent :弯曲Elastic deformation ：弹性变形Rheological property：流变性Structural building material：建筑材料Power line transmission pole:电线输送杆Primary criteria：主要标准Floor joists：地板格栅Rafter：椽子Wood frame home：木结构房子Roof sheet：屋面板Sub-flooring 地板底层用材Glue-laminated beam：层积梁Rail ：扶手，横档Upholster furniture：软包家具Engineering mechanics:工程力学Stress and strain：应力和应变Member:物体Impose :施加External force:外力Internal stress ：内应力Act on ：作用Transfer：转换Dimension :因次Proportional limit ：比例极限Slope：坡度Modulus of elasticity弹性模量Uniaxial：单轴Linear manner：线性关系Assumption ：假设Clear straight-grained wood：清晰的直纹理Knot ：节子Grain deviation：纹理扭曲Neutral axis:中性轴Lengthen：加长Bend ：弯曲Deflection：挠度Magnitude：幅度，重要性Bending test：弯曲试验Solid wood：实木Specimen:样品Concentrated load：集中荷载Span：跨度Solid wood 实木Particles：刨花Fiber :纤维Specimen :样品Concentrated load :集中载荷Sentence1 A wood that is relatively strong with respect to one strength property may rank lower in a different property as compared with other species.2 The change in length per unit of length in the direction of the stress is called the strain. Since strain is expressed in units of length divided by the length, it has no dimensions✧ 3 Below the proportional limit the ratioof stress to strain, i.e. ,the slope of theline, is a constant value called themodulus of elasticity (MOE).✧ 4 When a beam such as a wood floor joistis bent, the top half is stressed incompression and the bottom half isstressed in tension. The maximumstresses develop at the top and bottomsurfaces of the beam.✧ 5 Since no tensile or compressive stressesdevelop at the neutral axis of the beam,the length (AA in Fing.10.4) of theneutral axis remains the same when beamis bent, the top surface of the beam iscompressed and the bottom surface islengthened.questionsWhat are the mechanical properties? What are the structural uses for wood ? When there is linear relationship between stress and strain?What is the neutral axisLesson seven✓Physical properties物理性能Versatility:多用途Unmatched：不匹配✓Acoustical property：声学性能✓Thermal property：热性能✓Electrical property：电学性能Valuable：宝贵的✓Dampen：减震Vibration：震动✓Air dry 气干✓Douglas fir 北美黄杉气干密度0.52g/立方厘米（g/m3）✓Machine stress 机械应力✓Relative density：相对密度Deduce from推断✓Across the grain and parallel to the grainInternal friction：内摩擦Logarithmic decrement ：对数衰减Amplitude ：振幅Oscillation：震动Aluminum 铝✓Moisture content：含水率✓Absorption and isolation：吸附和隔绝✓Sound absorption coefficient:吸音系数✓Unfinished：未修饰的Heavily lined carpet 密织毛毯✓Roughness：粗糙度Striation ：条纹✓Sandblasting：喷砂Insulating quality：绝缘性✓Fastener：紧固件✓Sandwich：夹入Transmittance 透射系数Elastomer：弹性体✓Oven –dry：烘干，绝干✓Electric resistivity：电阻率✓Moisture meter：含水率测定仪✓High-frequency alternating：高频交流✓Curing of resin：树脂固化✓Radio frequency moisture meter高频含水率仪✓Dielectric constant：介电常数✓Power factor 功率因子Capacitance ：电容✓Polarization ：极化✓Adhesive：胶粘剂Key variable 重要变量✓Coefficient of thermal expansion：热膨胀系数Arise from：产生于Shrinkage :收缩✓Dimension stability :尺寸稳定Equivalent toDimensional stability 尺寸稳定性Poor conductor 不良导体Thermal insulator：绝热体Passage ：传输✓Thermal conductivity：导热系数✓Cell cavity ：细胞腔✓Kilndry：窑干✓Specific heat：比热Debark 去树皮Power consumption 功率消耗✓Thermal diffusivity：热扩散系数Have bearing on 有意义✓Fire-resistant material 阻燃材料✓Conditioning：调温调湿处理✓Veneer bolt：原木段Sentence✓The speed of sound andmodulus of elasticityboth decrease withincreasing moisturecontent and temperature.Because the transmittance decreasesas the logarithm of the weight, addingmass is not particularly effective inincreasing the insulation provided bya wall.The dielectric constant , can bedefined as the ratio of the capacitanceof a capacitor with some chosenmaterial as a dielectric to itscapacitance using a vacuum as thedielectricAn important acoustical property ofwood is its great ability to dampenvibrationsBecause the transmittance decreasesas the logarithm of the weight, addingmass is not particularly effective inincreasing the insulation provided bya wall.✓High—frequency alternating currents are used in the woodindustry primarily for thecuring of resin adhesives and toa lesser degree forradio—frequency moisturemeters and for drying woodrapidly.questionsWhy wood has great ability todampen the vibrations?What affect the logarithmicdecrement and how?What the sound absorption coefficientand how to improve the woodabsorption properties?Why is wood an excellent thermalinsulator?Why is the veneer bolt softened byheats before lathing?Lesson 8✓Fiber saturation point纤维饱和点✓Elastic property：弹性✓Cell wall细胞壁Long chain molecule长链分子Exponential relationship:指数关系✓Green 生材✓Red oak红橡木✓Age老化Deleterious effect:有害的作用Microorganism微生物Environmental factor 环境因子Per se本身，独自Impose施加，作用Load载荷✓Forest product林产品✓Deflect偏斜✓Deform扭曲Sag下垂✓Shelf搁板✓Creep蠕变✓Rheological property流体性能Slippage滑移Bonding site结合点Adjacent :邻近的Matrix基体Under stress:在力作用下Header:横梁（见图片）✓Floor joist 地板格栅Overload过载✓Coating涂饰Element :组成单元Random orientation:随即排列Allowable stress容许应力Oven dry绝干Critical structural member重要部件Cumulative累积Equilibrium temperature平衡温度Fatigue strength:疲劳强度Repeated severe loading:重复强荷载Rail car:火车车厢Clear straight grained wood:纹理通直无节材Knot：节子Slope of grain:斜纹理Static strength静强度Alkaline碱Resistant to acidic condition:耐酸性Corrosion :腐蚀Hydrolysis水解Oxidizing agent氧化剂Penetrate:渗透Severe condition:条件恶劣White oak白橡木Red oak红橡木（见图片）Douglas fir 花旗松Cypress:柏树Southern pine:南方松Old growth:原始林Second growth:次生林Fastener：紧固件Tannin单宁Corrode腐蚀Barn粮仓Nail螺钉Redwood红木Cedar雪松SentenceAging of wood alone without the deleterious effects of microorganisms, high temperature, or continuous loading has little effect on properties.Exposure to high temperatures for long periods can cause a permanent loss of strength. Generally, the higher the moisture content of the wood, the greater its sensitivity to high temperature.The fatigue strength of a material is its ability to retain its strength when subjected to repeated severe loading. Chemical deterioration of the cell wall, which results in strength loss, results from hydrolysis of cellulose, oxidation by oxidizing agents, or delignification by alkaliesquestions1Why is most strength increased when the wood is dried below the fiber saturation point? 2How to minimize the creep of wood products?3What is the cause of creep?4How to determine the allowable stress?5 What is fatigue strength? Lesson 9Agent 试剂Deterioration败坏Wood building ：木建筑Serve服务，使用Organic material ：有机物Be subject to 易于，遭受Decay腐朽Fungal stain 霉变Insect infestation虫蛀Surface weather 表面老化Use of life:使用寿命Out of door室外Indoor :：室内Marine borer 海生钻木动物Service life使用期Severe condition 使用条件Preventive measure预防措施Biological agent生物因子Stain:变色Soften软化Mollusk软体动物（见图片）Crustacean甲壳纲动物Termite白蚁Carpet ant木蚁Wood boring beetle蛀木甲虫Bio-deterioration生物败坏strong acid and alkali强酸和强碱Condensation 凝聚，浓缩Leakage渗漏Equilibrium moisture content 平衡含水率Practical ：实际的Treated materials处理过的材料Decay hazard腐朽危害Naturally decay resistant 天然耐腐性Construction wood :建筑木材Spruce：云杉Hemlock铁杉Durability：耐久性Western red cedar：北美圆柏Red wood：北美红杉Patio deck 庭院板材Second growth次生Old growth初生Inhibiting fungi寄生菌Volatility挥发性Leach流失Oil soluble油溶性Water borne水载型Heavy oil and light oil重油和轻油Carrier载体Retard：阻止或延缓Oil-based compound ：油溶型化合物Finish ：表面装饰Paint：涂饰Sound barrier健全防护带Coal tar creosote煤焦杂酚油(淡水中用木桩、电杆木和海上、陆地材的防腐处理Creosote coal tar solution杂酚煤焦油溶液Creosote –petroleum solution:杂酚油石油液Pentachlorophenol五氯苯酚Copper naphthenate环烷酸铜Water repellent防水剂Millwork建筑木线材Ammoniacal copper arsenite:氨化亚砷酸铜acid copper chromate酸性铬酸铜Chromated zinc chloride：加铬氯化锌Chromated copper arsenate加铬砷酸铜Chromium oxide：氧化铬Copper oxide：氧化铜Arsenic pentoxide：氧化砷Pressure retort加压罐Vacuum：真空Full cell and empty cell满腔和空腔法Incise 切割Power post beetle粉蛀虫Decomposition分解Drive off挥发Carbon dioxide二氧化碳Carbon monoxide一氧化碳Pyrolyze热解Carbon char炭Fire resistance耐火性Gypsum board石膏板Fire retardant阻燃剂Flammability可燃性Combustion燃烧Zinc chloride氯化锌✧Ammonium sulfate硫酸铵✧Diammonium phosphate磷酸铵✧Boric acid 硼酸✧Leach from :流失✧Interior application and exteriorapplication✧Concentration ：浓度✧inorganic salt：无机盐✧Hygroscopic吸湿性Relative humidity相对湿度Wood shingle 木屋顶板Partition分隔板Roughen粗糙化Weathering:风化Degradation :降解Latewood and early wood晚材和早材Detrimental :危害的Wood siding 批雨板Bleach:漂白剂SentenceHowever, as a naturally produced organic material,wood may be subject to decay, fungal stains, infestation, fire, and surface weathering, which can cause the useful life of a building or a product to be greatly reducedBiological agents are the major causes of wood deterioration, which results from fungi that cause staining, softening, and decay, marine borers, mainly small mollusks and crustaceans, insects including termites, carpenter ants, and a variety of wood-boring beetles, and bacteria that cause minor deterioration in water-stored logs.Because of the limited availability and high cost of naturally decay-resistant species, this approach is most suitable for applications where both durability and appearance is important.Wood preservatives in commercial use today are of two general types: oil-soluble chemicals and waterborne salts, The fundamental difference is the type of liquid used to carry the toxic chemicals into the wood structurequestions1 What are the major cause of wood deterioration?2 What are the greatest finical losses from bio-deterioration?3 Do what non -biological deterioration include?4 How to prevent or reduce wood decay?5What determine the wood natural resistance to decay?6 Why will the water-bornepreservative find more use?7What affect the effectiveness of a preservative treatmentLesson 10Green lumber生材Heartwood 心材Sapwood边材Hygroscopic吸水的Propensity倾向Swell and shrink膨胀与收缩Dimensional change尺寸变化In service服务，使用Wood stain mold木材变色菌Decay producing fungi腐朽菌Railway tie铁轨枕木Fence post:栅栏Utility pole：电线杆Check开裂Free water自由水Fire-retarded:阻燃处理Unimpeded：无妨碍Veneer ：单板（见图）Plywood ：胶合板（见图）Glued laminated beam：胶合层积梁（见图）Curing temperature固化温度Finish装饰Anatomy ：解剖构造Living tree：活立木Cell lumen：细胞腔Pit：纹孔Tracheid：管胞Circumference：周边Permeability：渗透性Free water：自由水Bound water结合水Capillary force毛细管力Hydrogen bond氢键Fiber saturation point纤维饱和点Equilibrium moisture content含水率Relative humidity：相对湿度Outdoor condition：室外条件Cover open shed:：敞开有盖棚Woodwork：建筑木线条Desorb：解吸Absorb：吸附Hysteresis 吸湿滞后Latent heat of evaporation蒸发潜热Heating of wetting ：润湿热Vapor pressure蒸汽压Closed container密闭容器Saturated vapor pressure：饱和蒸汽压Function：功能Transport：输送Replenish装满Recede：凹进Spherical depression:球星凹面Menisci 弯液面Capillary flow毛细管流Permeability渗透Mechanism机理Vapor diffusion蒸汽扩散Random manner：随意方式Pressure gradient:蒸汽梯度Moisture gradient：含水率梯度End of lumber：锯材端部Block，木段Mass flow质流Split：开裂Degrade：降解Tempt诱惑Expedient：便利的Indiscriminately：不加区别的Drying defects:干燥缺陷Non-homogeneous 非均相的Western red cedar 北美乔柏Case hardening表层硬化Tangential：弦向的Radial ：径向的Initial stage初始阶段Stretch拉伸Tension set拉伸变定Rip-saw纵锯Binding saw:夹锯Bowed stock 弓弯方材Prong齿片Bulb dry temperature干球温度Collapse塌陷Rupture开裂Crack裂隙End trimming 截头Cupping瓦形弯曲Roller check 碾压裂纹Sticker 隔条Spacer 间隔条Bow 瓦形弯曲Shake轮裂Radio frequency drying：高频干燥Freeze drying：冷冻干燥solar drying ：太阳能干燥De-humidification drying ：除湿干燥SentenceWood is a hygroscopic material, which means that it absorbs or gives off moisture in response to humidity changes in the surrounding atmosphere. It has a natural propensity to swell and shrink as its moisture content increases and decreases in the range from oven-dry to 30%.✧The transportation route forwater in the living tree isvertically through the sapwoodcell lumens and from cell to cellthrough the pits connecting thecells.✧Moisture in wood exists in threeprincipal forms: free water,which is liquid water within thecell lumen; water vapor togetherwith air occupies that part of thecell lumen not occupied by freewater; and bound water, which isadsorbed in the cell wall✧Wood left exposed to air at aconstant relative humidity andtemperature will eventuallyattain a constant moisturecontent. This moisture content,which is at equilibrium with itssurrounding atmosphere, isknown as the equilibriummoisture content✧Because the contribution ofcapillary flow to the dryingprocess depends on thepermeability of the wood, itvaries considerably betweenspecies and between heart woodand sapwood of the samespecies.questions1What are the most important reason for wood drying?2What are forms of water in wood?3What are the roles of atmosphere in wood drying?4In permeable wood what contributed most to the moisture movement to wood surface?Lesson 11Glue line胶层Waterproof防水resistance to weather耐候性Set固定，变定Cross linking交联Postage stamp邮票Be coated with涂饰Dextrin gum糊精Wet润湿Diffuse :扩散Revert to恢复Rubber cement橡胶Organic solvent有机溶剂Polyvinyl acetate聚醋酸乙烯Latex乳液Water-based paint水性涂料Hot-melt gluing热熔胶合Roof felt屋面毡Roof sheathing 屋面盖板Epoxy resin环氧树脂Tough：韧性Durable ：耐久性Polymerize聚合Urea-formaldehyde脲醛树脂Overlay：贴面Decorative：装饰Vinyl plastic 乙烯塑料Resorcinol formaldehyde间苯二酚甲醛树脂Precursor预聚体Para formaldehyde多聚甲醛Filler：填料Phenol：苯酚De-polymerize解聚Novolak线性酚醛树脂Finger-jointed lumber指接板Phenol formaldehyde酚醛树脂formulationCaustic soda碱性钠Sodium hydroxide氢氧化钠Hot-pressing热压Wafer board：华夫板Colorless line无色胶层Stain：变色Extender补充剂，增量剂Radio frequency ：高频Melamine：三聚氰胺Formaldehyde ：甲醛Hardening agent固化剂Ammonium chloride氯化铵Cold set：冷固化Hot set：热固化Animal glue：动物胶Casein glue：酪素胶黏剂Fortify强化Formulation配方Water resistance耐水Pot life贮存期Clay粘土Speed up加速Case good ：柜架类物品Isocyanate：异氰酸酯SentenceGluing is basically an operation in which a liquid material is spread between the surfaces of the materials to be joined, and the two surfaces are held in intimate contact until the liquid has changed to a solid formThe types of adhesives used fall into two general classes. One class is composed of the structural adhesives, which are rigid adhesives that form a glue bond that is harder and stronger than the wood itself. The other class is composed of the elastomeric adhesives, which form glue lines that are weaker than the wood and are usually softened by heat or moisture or both.The virtues of MF resin adhesives are that they form acolorless glue line, arenon-staining and can be readilyadapted to gluing processes thatuse radiofrequency heating toaccelerate the cure of the glueline.questions1What are the four mechanism for glue setting?What are the two purposes of adhesives used on wood industry?Lesson 12 Comprise ：包含，组成Veneer：单板Grain direction纹理方向At right angle to垂直于Adjacent 邻近Cross lamination：交叉层积Versatile building material ：通用型建筑材料Hardwood and softwood硬材和软材Deck铺板，甲板Debark去树皮Block木段Tier：堆垛成层Power driven：动力驱动Scrape away刮掉，擦掉Hot water vat热水罐Rotary-cut旋切Rotary Lathe旋切机Chuck卡头Spindle卡轴Revolve旋切Carriage跑车Spindless lathe：无卡轴旋切机Roller:滚筒Peel旋切Round up旋圆Yield产出Unwound：防索，松卷Knot结子Conveyor传送带Embed:镶嵌Feed into:输送Clipper剪板机Damper:风挡Grade：分等Pitch pocket树脂囊Edge gluing 边缘涂胶Panel patch板的嵌补Scarf斜接Splice ：拼接String线拼接Patch:嵌补Scarf：斜接Interior plywoodExterior exposureWaterproof防水Roller spreader辊涂机Spray line喷涂生产线Curtain coater淋涂机Assemble组装Excessive gap：过多搭接Ridge 脊Pre-press：预压Cold press：冷压Stationary platen：固定垫板Hydraulic ram:液压柱Heat platen热板Tack初粘性Hydraulic ram液压柱塞Workmanship工艺Patch hole嵌补孔Lesson 13Particleboard 刨花板Dry-process干法Fiberboard纤维板Bonding agent胶合剂Composition board复合板Hardboard硬质纤维板Insulation board绝缘板Cement-bonded board水泥板材Molded products模压产品Corrugation：瓦形，波状Sawn lumber：锯材Long-term load carrying ability长期荷载能力Surpass超过Modify修改Fire retardant阻燃剂Preservative：防腐剂Stabilizing impregnation：稳定性浸渍Binding agent胶合剂Binder胶合剂Inorganic cement无机水泥Medium density fiberboard中密度纤维板Fibrous slurry纤维浆料Platen-pressed system平压系统Extruded system挤压系统Heated die热磨具Flaker 刨片机Wafer大片刨花Attrition mill磨浆机Planer刨床Furnish碎料Blending step混合步骤Wax石蜡Mat of particle刨花板坯Multi opening press多层压机Single-opening press单程压机Continuous press连续压机Isocyanate binder异氰酸酯胶黏剂Floor underlayment地板底层Cabinet柜Mobile home活动房子Decking甲板，铺板Sheathing盖板Siding挡板Wood veneer face 木单板Ring-cut flaker环式刨片机Planer shaving工厂刨花Pressure-refined fiber加压精磨机Internal bond内结合Compression strength压缩强度Shear strength剪切强度Glue line shear胶层剪切Nail resistance抗钉力Water absorption吸水Paint涂料Durability耐久性Accelerated aging加速老化Fire retardant阻燃性的Static fatigue静止强度Fire hazard火灾Ring porous diffuse porous semi-ring porous定义、区别。
化工原理(1)(全英文)智慧树知到答案章节测试2023年山东科技大学
绪论单元测试1.The unit operation of separation of gas mixture based on the difference ofcomponents’solubility is . 利用气体各组分在液体中的溶解度的不同而实现气体分离的单元操作是。
（）A:Distillation 精馏B:Extraction萃取C:Adsorption吸附D:Absorption吸收答案:D2.Please judge which following unit operation belongs to mass transfer? 请判断哪个单元操作属于质量传递? ( )A:Distillation 精馏B:Heating 加热C:Filtration 过滤D:Settling 沉降答案:A3.Which unit operation belongs to heat transfer? 哪个单元操作属于热量传递?( )A:Settling 沉降B:Transportation of fluids 流体输送C:Stirring 搅拌D:Cooling 冷却答案:D4.As we all know, “three transfers” is a very important concept, which includesmomentum, heat, and mass transfer, now judge which following unitoperation belongs to momentum transfer? 总所周知，三传是非常重要的概念，它包括动量、热量和质量传递，请判断哪个单元操作属于动量传递?( ) A:Cooling 冷却B:Absorption吸收C:Transportation of fluids 流体输送D:Distillation精馏答案:C5.Some unit operations just include 1 transfer, however others maybe include2 or3 transfers at the same time, please indicate the unit operation belowthat exists mass and heat transfers meanwhile?一些单元操作只存在一种传递，有些则同时存在2到3种单元操作，请指出下面哪个单元操作既属于质量传递同时也属于热量传递？( )A:Transportation of fluids 流体输送B:Heating加热C:Cooling 冷却D:Distillation精馏答案:D第一章测试1.Gas is a compressible fluid. 气体是一种可压缩性的流体。
土木工程专业英语课后翻译
一.1.受压构件是只承受轴向压力的结构构件。
Compression members are those structural elements that are subjected only to axial compressive forces.2.公式1.1要成立，构件必须是弹性的并且其两端能自由转动但不能横向移动。
For Eq.1.1 to be valid,the member must be elastic,and it's ends must be free to rotate but not translate laterally.3.临界荷载有时被称为欧拉荷载或欧拉屈服荷载。
The critical load is sometimes referred to as the Euler load or the Euler buckling load.4.图1.2中的应力-应变曲线不同于延性钢的应力-应变曲线，因为它有明显的非线性区域。
The stress-strain curve in Fig.1.2 is differet from the ones for ductile steel because it has a pronounced region of nonlinearity.5.其他因素，像焊接和冷弯，都能影响残余应力，但冷却过程是残余应力的主要来源。
Other factors,such as welding and cold bending to create curvature in a beam, can contribute to be the residual stress,but the cooling process is the chief source.二1。
作用在结构上的力被称为荷载The forces that act on a structure are called loads.2．恒载就是固定不变的荷载，包括结构自身的重量。
材料成形及控制工程-专业英语阅读
CHAPTER I MA TERIALS AND THEIR PROPERTIES1. 1 Metals and Non-metalsAmong numerous properties possessed by materials, their mechanical properties, in the majority of cases, are the most essential and therefore, they will be given much consideration in the book. All critical parts and elements, of which a high reliability is required, are made of metals, rather than of glass, plastics or stone. As has been given in Sec 1-l, metals are characterized by the metallic bond; where positive ions occupy the sites of the crystal lattice and are surrounded by electron gas .All non-metals have an ionic or a covalent bond. These types of bond are rigid and are due to electrostatic attraction of two ions of unlike charges. Because of the metallic bond, metals are capable of plastic deformation and self-strengthening upon plastic deformation. Therefore, if there is a defect in a material or if the shape of an element is such that there are stress concentrators, the stresses in these points may attain a great value and even cause cracking. But since the plasticity of the material is high, the metal is deformed plastically in that point, say, at the tip of a crack, undergoes strengthening, and the process of fracture comes to an arrest. This does not occur in non-metals. They are uncapable of plastic deformation and self-strengthening; therefore, fracture will occur as soon as the stresses at the tip of a defect exceed a definite value. These facts explain why metals are reliable structural materials and can not be excelled by non-metallic materials.Words and Terms:mechanical property 机械（力学）性能critical part and element 关键零部件covalent bond 共价键metalic bond crystal lattice 金属键晶格electrostatic attraction 静电吸引plastic deformation 塑性变形self-strengthening 自强化stress oncentrator 应力集中点the tip of a crack 裂纹尖端Questions: 1) What are the differences in properties between metals and non-metals?2) Why are metals capable of plastic deformation and self-strengthening?1. 2 Ferrous AlloysMore than 90 % by weight of the metallic materials used by human beings are ferrous alloys. This represents an immense family of engineering materials with a wide range of microstructures and related properties. The majority of engineering designs that require structural load support or power transmission involve ferrous alloys. As a practical matter, these alloys fall into two broad categories based on the carbon in the alloy composition. Steel generally contains between 0. 05 and 2.0 wt % carbon. The cast irons generally contain between 2.0 and 4.5 wt % carbon. Within the steel category，we shall distinguish whether or not a significant amount of alloying elements other than carbon is used . A composition of 5 wt % total non-carbon additions will serve as an arbitrary boundary between low alloy and high alloy steels. These alloy additions are chosen carefully because they invariably bring with them sharply increased materials costs. They are justified only by essential improvements in properties such as higher strength or improved corrosion resistance.Words and Terms:ferrous 铁的；含铁的corrosion resistance 耐腐蚀；抗蚀力arbitrary 特定的；武断的Questions:l) What is the difference in composition between steel and cast iron?2) How can you distinguish low alloy steels from high alloy steels?CHAPTER 2 HEA T TREA TMENT OF STEEL2. 1 Principle of Heat Treatment of SteelThe role of heat treatment in modern mechanical engineering cannot be overestimated. The changes in the properties of metals due to heat treatment are of extremely great significance.2. 1. 1 Temperature and TimeThe purpose of any heat treating process is to produce the desired changes in the structure of metal by heating to a specified temperature and by subsequent cooling.Therefore , the main factors acting in heat treatment are temperature and time , so that any processof heat treatment can be represented in temperature-time ( t-τ) coordinates .Heat treatment conditions are characterized by the following parameters: heating temperature t , i.e. the maximum temperature to which an alloy metal is heated; time of holding at the maxheating temperatureτh; heating rate νh and cooling rateνc．If heating (or cooling) is made at a constant rate, the temperature-time relationship will be described by a straight line with a respective angle of incline.With a varing heating (or cooling) rate , the actual rate should be attributed to the given temperature , more strictly , to an infinite change of temperature and time : that is the first derivative of temperature in time : νact = dt/dτ.Heat treatment may be a complex process , including multiple heating stages , interrupted or stepwise heating (cooling) , cooling to subzero temperatures , etc . Any process of heat treatment can be described by a diagram in temperature-time coordinates.Words and Terms:coordinates 坐标系heating rate 加热速度straight line 直线heating temperature 加热温度cooling rate 冷却速度first derivative 一阶导数Questions:1) What are the two main factors acting in heat treatment?2) How many stages may usually be inc luded in the heat treatment of steel?2. 1. 2 Formation of AusteniteThe transformation of pearlite into austenite can only take place at the equilibrium critical point on a very slow heating as follows from the Fe-C constitutional diagram. Under common conditions, the transformation is retarded and results in overheating, i.e. occurs at temperatures slightly higher than those indicated in the Fe-C diagram.When overheated above the critical point, pearlite transforms into austenite, the rate of transformation being dependent on the degree of overheating.The time of transformation at various temperatures (depending on the degree of overheating) shows that the transformation takes place faster (in a shorter time) at a higher temperature and occurs at a higher temperature on a quicker heating. For instance , on quick heating and holding at 780 ℃，the pearlite to austenite transformation is completed in 2 minutes and on holding at 740 ℃，in 8 minutes .The end of the transformation is characterized by the formation of austenite and the disappearance of pearlite (ferrite + cementite). This austenite is however inhomogeneous even in the volume of a single grain. In places earlier occupied by lamellae (or grains) of a pearlitic cementite , the content of carbon is greater than in places of ferritic lamellae . This is why the austenite just formed is inhomogeneous .In order to obtain homogeneous austenite , it is essential on heating not only to pass through the point of the end of pearlite to austenite transformation , but also to overheat the steel above that point and to allow a holding time to complete the diffusion processes in austenitc grains.The rate of homogenization of austenite appreciably depends on the original structure of the steel, in particular on the dispersion and particle shape of cementite. The transformations described occur more quickly when cementite particles are fine and, c therefore, have a large total surface area.Words and Terms : pearlite 珠光体constitutional diagrm 状态图inhomogeneous 不均匀的lamellae 层片critical point 临界温度overheat 过热grain 晶粒diffuse扩散Questions:1) Is there no diffusion process in the transformation from pearlite to austenite?2) Is it true that the higher the temperature, the faster the transformation from pearlite into austenite?3) How to obtain homogeneous austenite?CHAPTER 3 PRINCIPLES OF PLASTIC FORMING3. 1 Physical Metallurgy of Hot WorkingThe principles of the physical metallurgy of hot working are now well recognized. During the deformation process itself, e.g. a rolling pass, work hardening takes place but is balanced by the dynamic softening processes of recovery and recrystallization. These processes, which are thermally activated, lead to a flow stress that depends on strain rate and temperature as well as on strain. The structural changes taking place within the material result in an increase in dislocation density with strain until in austenitic steels and nickel- and copper-base alloys a critical strain （εc）is reached when the stored energy is sufficiently high to cause dynamic recrystallization . With further strain, dynamic recrystallization takes place repeatedly as the new recrystallized grains are themselves work-hardened to the critical level of stored energy. These dynamic structural changes leave the metal in an unstable state and provide the driving force for static recovery and static recrystallization to take place after the deformation pass. Static recrystallization may be followed by grain growth if the temperature is sufficiently high. In order to be able to apply these principles to commercial working processes, we require answers to two main questions: (a) how long does recrystallization take place after a deformation pass; and (b) what grain size is produced by recrystallization and grain growth? The answers determine the structure of the material entering the next and subsequent passes and hence influence the flow stress of the material and the working forces required. Eventually they determine the structure and properties of the hot worked products.Words and Terms : physical metallurgy 物理冶金work hardening 加工硬化static recovery静态回复thermally activated 热激活的hot working 热加工dynamic softening 动态软化recrystallization 再结晶dislocation density 位错密度critical strain 临界应变Questions:l) When does dynamic recrystallization take place within the material work hardened?2) What do the answers to the two questions determine?3. 1. 1 Dynamic Structural ChangeDuring the deformation of austenite at hot-working temperatures and constant strain rate, the characteristic form of stress-strain curve observed is illustrated in Fig. 3. 1. These curves are for low-alloy steels, tested in torsion, but are similar to those obtained for other steels in the austenitic condition tested in torsion, tension, or compression. After initial rapid work- hardening the curves go through a maximum associated with the occurrence of dynamic recrystallization. The peak in flow stress occurs after some low fraction of recrystallization has taken place so the strain to the peak(εp) is always greater than the critical strain for dynamic recystallization (εc ) . The relationship between the two strains is complex , but it has been suggested thatεc＝αεp( where αis a constant ) is a reasonable approximation for conditions of deformation of interest in hot working. however , the proposed values of αdiffer , being 0.83 , 0.86 , and 0.67 . It can be seen from Fig.3.1 that εp increases systematically with Zener-Hollomon parameter ( Z ) , independent of the particular combination of stain rate （ε）and temperature ( T / K ) in the relationship : Z=εexp Q def/RTWhere the activation energy Q def for this alloy steel is 314 kJ/mol. A similar value of 312kJ/mol is appropriate for a range of C-Mn steels but lower values of 270 and 286 kJ/mol have also been observed.Asεc marks a change in microstructure from one of somewhat poorly developed subgrains , produced by the action of work hardening and dynamic recovery，to one which also contains recrystallization nuclei , it is also a critical strain in terms of the static structural changes that take place after deformation . The dependence of εp，and hence of εc，on Z is shown for the low-alloy steel and a number of C-Mn steels in Fig. 3.2. It can be seen that, indicated by the Fig.3.2 ，εp generally increases with increasing Z although the curve for the data of Sakui et al. passes through a minimum at Z = 3 x 10s-1，( corrected to Q def = 312 kcal / mol ) . The curves for the data of Nakamura and Ueki, Cook, Rossard and Blain, and Hughes, and also the data of Suzuki et al. for a number of C-Mn steels were obtained from tests on material reheated to the same temperature as the testing temperature.These all show a trend for higher values of εp at higher testing temperatures.In contrast, the curves for the data of Le Bon et al. , Barraclough , and Morrision refer to tests carried out at lower temperature than the reheating temperature and these show no effect of test temperature 0n εp.In the former group of results, higher reheating/test temperatures will give larger initial grain sizes. As shown by Sah et al., Sakui et al., and Roberts et al. , increase in grain size ( d0）leads to an increase inεp and their data indicate a relationship of the form εp∝d0^ 1/2 Words and TermsStress-strain curve 应力应变曲线torsion 扭转;转矩activation energy 激活能initial grain size 原始晶粒尺寸Questions:l ) What doεc andεp mark ?2 ) What is the relationship between εc andεp ?3. 1. 2 Static Recrystallization RateAfter deformation, softening by static recovery and recrystallization take place with time at rates which depend on the prior deformation conditions and the holding temperature. These processes may be followed by studying the changes in yield or flow stress during a second deformation given after different holding times to obtain a restoration index, or recrystallization may be measured directly by metallographic examination of quenched specimens. An example of the form of recrystallization curves obtained by the latter method for low-alloy steel is shown inFig 3.3. The curves generally follow an A vrami equation of the formwhere X v is the fraction recrystallized in time t ; t F is the time for some specified fraction of recrystallization ( say 0.5 ) ; k is a constant ; and C＝-In ( 1－F ) . For the Curves shown k = 2 , which is consistent with the value observed for other steels deformed to strains <εc．With this relationship t0.05＝0 . 27t0.5 and t0.95 = 2.08 t0.5 , i.e. recrystallization proceeds over about one order of magnitude in time.The dependence on strain of the characteristic time t0.5, measured by either metallographic or restoration method, is shown for several steels in Fig. 3.4. All the curves show a steep dependence on strain for strains up to ~0. 8εp，which fits a relationship t0.5∝ε-m , where the mean value of m = 4 . This value is also given by observations on ferritic metals. The lower limit of strain to which this relationship is applicable is uncertain as the critical strain for static recrystallization has not received systematic study. The data of Norrison indicate that it is < 0.05 for low-carbon steel at 950℃whereas the observations of Djaic and Jonas indicate a value of > 0.055 for high-carbon steel at 780 ℃．It is clear whether this difference arises from thedifference in temperature or composition as the simple dependence on Z suggested by the broken line in Fig. 3.2 may be unrealistic. This deserves further study as low strains my be applied in the final passes of plate rolling and , as shown previously , these could have significant effects on the final grain size if they exceed the critical strain for static recrystallization.In the strain range of steep dependence of t0.5 on ε，Morrison observed that there was no effect of strain rate over the two orders of magnitude studied . This is somewhat surprising as interesting strain rate (or Z) increases the flow stress at any particular strain. Increasing flow stress would be expected to increase the random dislocation density and decrease the subgrain size and hence increase the stored energy．The subgrain boundaries provide the largest contribution to the stored energy and as their misorientation increases with strain, the driving force for recrystallization will increase. However, this increase would be expected to be about linear with strain so the much greater dependence of t0.5on strain must also arise from an increase in density of nucleation sites and in nucleation rate. The lack of influence of strain rate may thus reflect compensating effects on stored energy and substructure development at any strain. This contrasts with the strain rate effect observed for stainless steel.The observations of Djaic and Jonas indicate that an abrupt change takes place from strain dependence to independence at a strain ~0.8εp，as illustrated in Fig . 3. 4. This corresponds reasonably with the strain expected forεc and arises because preexisting recrystallization nuclei are always present in the deformed structure at strains greater thanεc．Static recrystallization under these conditions has been referred to as ‟metadynamic‟ to distinguish it from the 'classical ' recrystallization after lower strains when the nuclei must be formed after deformation . The restoration measurements indicate that the recrystallization kinetics may have a complex form after strains betweenεc and the onset of steady state , and direct metallographic observations of static recrystallization after stains well into steady state show that the exponent k in the A vrami equation drops to a value of ~1 . This means that t0.05 = 0.074 t0.5 and t0.95 = 4.33 t0..5, i. e. static recrystallization proceeds over about two orders of magnitude in time after strains which give dynamically recrystallized structures during deformation 。
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doi: 10.1098/rstl.1886.0005, 157-234177 1886 Phil. Trans. R. Soc. Lond. Osborne Reynolds Determination of the Viscosity of Olive OilExperimentalBeauchamp Tower's Experiments, Including an On the Theory of Lubrication and Its Application to Mr. Referenceshttp://rstl.royalsocietypublishing.org/content/177/157.citation#related-urls Article cited in:
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http://rstl.royalsocietypublishing.org/subscriptions go to: Phil. Trans. R. Soc. Lond.To subscribe to This journal is © 1886 The Royal SocietyThe Royal Society is collaborating with JSTOR to digitize, preserve, and extend access toPhilosophical Transactions of the Royal Society of London.www.jstor.org®
[ 157 ] IV. On the TheOt'Y of Lubrication and its Application to Mr.
BEAUCHAMP TOWER'S
Experiments, including an Experimental Determination of the Viscosity of Olive Oil.
By P'rofessor OSBOH-NE REYNOLDS, LL.D., F.R.S.
Received December 29, 1885,-Read February 11, 1886. [PLATE 8.J
CONTENTS. SECTION I.-INTRODUCTORY. ARTICLE. Discordance ot experimental results .• , ..... ,." .... ,.,.,., ..............•.. , 1
Mr. TOWER'S discovery of the separating film of oil, &c ....................... , . . . 2 Tha idea of a hydrodynamical theory of lubrication .. " ..••..... , .. , ... , . . .. . .• . .3 The equation of lubrication mentioned before Section A, Montreal, and subsequently integrated .....................•..............••....................•• 4 ,The comparison of the theoretical results w:ith experimental shows a temperature effect 5 Determination of the variation of viscosity of olive oil brings the theory into complete accordance with experiments, and shows how various circumstances affect the results ...•..••. ' ..... , . '. . . . . • • .• ... . . . . . . . . . . . . .. .. . . . . . . .• . . . . . . . . . . . • 6 The difference in the radii of brass and journal, and the point of nearest approaeh of brass to journal, and explanation of increase,Cl. heating on first reversal. '. . . .. . . . . '7 The limits of complete lubrication, incomplete lubrication, and necking ............ 7A The general arrangement of the paper ......................................... 8
SECTION n.-THE PROPERTIES OF LUBRICANTS. Definition of viscosity ........................... , ............................ '. 9 The character of viscosity ............. ' ......•.........•.................. , . . . 10 The two viflcosities ...•............ , ................. " • , ......... ' . . . . . . . . . . . . • 11 Expe~imental determination'of the value of ft for olive oil, &c.,f).gs: 2 and 3, Table 1. 12
The comparative values for ft for different fluids apd different units. • . . . . . • . . . . . . . . 13
SEC'l'ION IlL-GENERAl! VIEW OF THE ACTION OF LUBRICATION. The case of two nearly parallel surfaces separated by a viscous fluid ....... " .• .. . . . . 14 The cltSe of revolving cylindrical surface .... ,................................. 15 The effect of limited supply of lubricating material ................... ; . , . . . • . . .. 16 The relation between resistance, load,and speed for limited lubrication ~.'......... 17 The conditions of equilibrium with cylindrical surfaces ...•................ ,. . . . . 17.A The weal' and heating of bearings ...... , ... , ..... , .. .' ...... " ...... "........ 18 158 PROFESSOR O. REYNOLDS ON THE 'fHEORY O:F LUBRICATION
SECTION IV.-THIl EQUATIONS OF HYDRODYNAMICS AS ApPLIED TO LUBRICATION. ,\RTICLE. The complete equations for interior of viscous fluid simplified .................... 19
The boundary conditions .........•.....................................•.•.. 20 The first integration of the resulting equations-equations of lubrication. . . . . . . . . . . • 21 The conditions under which further integration has been undertaken. . . . . . . . . . . . . • 22
SECTION V.-ApPLICATION '1'0 CASES IN WHICH THE EQUATIONS ARE COMPLETELY INTEGRABLE. Parallel plane surfaces approaching each other, the surfaces having elliptical boundaries 23 Plane surfaces of unlimited length .....•.................•...•..• , . . . . . . . . . • . . 24
SECTION Vr.-THE INTEGRA'fION OF THE EQUATIONS FOR CYLINDRICAL SURFACES. General adaptation of the equations .................................•.•.....• 25 The method of approximate integration .•........ , . . . . . . . . . . . . . . . . . . . . . . . . . . . . • 215 Integration of the equations ............................ '. . . . . . . . . . . . . . . . . . • . • 27