2021年2021年度工程力学专业英语翻译讲义.ppt

By making an artificial cut (section mm) through the bar at right angles to its axis, we can isolate part of the bar as a free body [see (b)]. At the left-hand end the tensile force P is applied, and at the other end there are forces representing the action of the removed portion of the bar upon the part that remains. These forces will be continuously distributed over the part cross section, analogous to the continuous distribution of hydrostatic pressure over a submerged surface.
假设在梁的轴向上做一个垂直截面（截面mm），可以分离出一部分自由的梁[见图1(b)]。在该梁的左端，有拉力P，而在另一端有相应的力可以替代梁的分离部分对它的作用。这些力连续分布在横截面上，类似于在水平面下的静水压力的连续分布。
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工程力学专业英语翻译
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The intensity of force, that is, the force per unit area, is called the stress and is commonly denoted by the Greek letter σ. Assuming that the stress has a uniform distribution over the cross section [see (b)], we can readily see that its resultant is equal to the intensity σ times the cross-sectional area A of the bar. Furthermore, from the equilibrium of the body shown in (b), we can also see that this resultant must be equal in magnitude and opposite in direction to the force P. Hence, we obtain σ = P/A. (1)
力的强度，也就是说单位面积上的力，被称为应力，通常用希腊字母σ来表示。假定应力在横截面上均匀分布[见图1 ( b )]，那么我们可以很容易的看出它的合力等于强度σ乘以梁的横截面积A。而且，从图1上显示的物体的平衡来看，我们可以发现这个合力是跟拉力P在数值上相等，方向相反的。因此，我们得到方程（1）σ = P/A。
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工程力学专业英语翻译
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Eq.(1) can be regarded as the equation for the uniform stress in a prismatic bar. This equation shown that stress has units of force divided by area. When the bar is being stretched by the force P , as shown in the figure, the resulting stress is a tensile stress; if the forces are reversed in direction, causing the bar to be compressed, they are called compressive stress.
方程(1) 用于求解在梁中均匀分布的应力问题。它表示了应力的单位是力除以面积。正如我们在图1中所看到的，当梁被力P拉伸的时候，生成的应力是拉应力；如果力的方向被颠倒，导致梁被压缩时，产生的应力被称为压应力。
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工程力学专业英语翻译
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A necessary condition for Eq.(1) to be valid is that the stress σ must be uniform over the cross section of the bar. This condition will be realized if the axi