工程力学专业英语阅读2

随着载荷的增加，应变比应力增加得更快，
当应力达到B点的相应值以后，应力没有明显增加，
但物体的变形却在增长。这种现象叫做材料的屈 服，点B处的应力叫做屈服点或屈服应力。在区域 BC上材料开始具有塑性，杆件也开始塑性伸长， 塑性伸长量一般为材料弹性伸长量的10或15倍。
Section 4
应变硬化
4. At point C the material begins to strain harden and to offer additional resistance to increase in load .Thus, with further elongation the stress increases, and it reaches its maximum value, or ultimate stress, at point D. Beyond this point further stretching of the bar is accompanied by a reduction in the load, and fracture of the specimen finally occurs at point E on the diagram.
actual cross-sectional area at the narrow part of the neck is used in calculating , it will be found that the true stress-strain curve follows the dashed line CE. Whereas the total load the bar can carry does indeed diminish after the ultimate stress is reached (line DE), this reduction is due to the decrease in area and not to a loss in strength of the material itself.
sectional area, and the strain is found by dividing the elongation
by the length along which the elongation occurs. In this manner a complete stress-strain diagram can be obtained for the material.
Section 2
纵坐标
The typical shape of the stress-strain diagram for structural steel is shown in Fig.1, where the axial strains are plotted on the horizontal axis and the corresponding stresses are given by the ordinates to the curve OABCDE. From O to A the stress and strain are directly proportional to one another and the diagram is linear .Beyond point A the linear relationship between stress and strain no longer exists, hence the stress at A is called the proportional limit.
因此材料在失效之前，材料强度并未降低，
实际上能够承受应力的增加。不过在实际的工程
试样变形达到点D之后，试样在某一小段内会
发生明显的颈缩(如图2所示)，如果采用颈缩处的
实际横截面积计算应力，将会发现真实的应力应 变曲线将沿着虚线 CE’。由此，尽管在极限应力 达到之后，杆件承受的总荷载有所减小，但减小 的原因是由于杆件截面积的减小，而不是由于材
料强度的降低。
Section 6
完全的， 完整的
拉伸测试可以用来确定材料的应力、应变关
系。测试材料的试样通常选用圆柱形，将试样放
置在测试机上，使其承受拉力。当载荷增加时， 测量杆件所受的拉力以及杆件相应的伸长。然后 将拉力除以横截面积可以得到杆件横截面的应力， 轴向伸长量除以杆件长度可以得到相应的应变。
进而得到材料的完整应力应变图。
6. The material actually withstands an increase in stress up to the point of failure. For most practical purposes, however, the conventional stress-strain curve OABCDE, based upon the original cross-sectional area of the specimen, provides satisfactory information for design purposes.
在伸长阶段中，试样伴随横向收缩，导致杆 件的横截面积减小。在点C之前，这个现象对应力 应变图没有影响，但是过了这一点，横截面面积
的减小对应力的计算值有明显的影响。
明显的 续 5. A pronounced necking of the bar occurs (see Fig.2), and if the
四、词的搭配
遇到动词、形容词与名词搭配时，应根据汉语的搭配 习惯，而不应受原文字面意义的束缚。
The iron ore used to make steel comes from open-pit and underground mines. 炼钢用的铁矿石来自露天开采的矿山和地下矿井。 （不译“制造钢”） An insulator offers a very high resistance to the passage through which electric current goes. 绝缘体对电流通过有很大阻力。（不译“高阻力”）
the material, usually in the form of a round bar, is placed in a testing machine and subjected to tension. The force on the bar and the elongation of the bar are measured as the load is increased. The stress in the bar is found by dividing the force by the cross-
Lesson 2
Tensile Stress-strain Behavior
Section 1
1. The relationship between stress and strain in a particular
material is determined by means of a tensile test. A specimen of
结构钢的应力应变曲线如图1OABCDE所示，
其中横轴表示轴向应变，纵轴表示相应的应力。
图中O到A的图线为直线，即应力应变满足线性关
系。过了A点，应力应变不再存在线性关系，因此
称A点处的应力为材料的比例极限。
Section 3
相当大的
3. With an increase in loading, the increases more rapidly than the stress, until at point B a considerable elongation begins to occur with no appreciable increase in the tensile force. This phenomenon is known as yielding of the material, and the stress at point B is called the yield point or yield stress. In the region BC material is said to have become plastic, and the bar may actually elongate plastically by an amount which is 10 or 15 times the elongation which occurs up to the proportional limit.
过了C点，材料又恢复了抵抗变形的能力，即
必须增加拉力才能使材料继续变形，这种现象称 为材料硬化。由此，随着应力进一步增加，应力 达到应力的最大值点D，称为强度极限。过了D点， 应力随着变形的增加反而下降，直到点E试样断裂。
Section 5
横向收缩
5. During elongation of the bar a lateral contraction occurs, resulting in a decrease in the cross-sectional area of the bar. This phenomenon has no effect on the stress-strain diagram up to about point C, but beyond that point the decease in area will have a noticeable effect upon the calculated value of stress.
三、词义抽象化
把原文中词义较具体的词引申为词义较抽象的词，或 把词义较形象的词引申为词义较一般的词。