土木工程文章英译汉To give you some insight into the design cycle,an e

土木工程文章英译汉
To give you some insight into the design cycle,an extremely simple member will be dealt with first..That member is a prismatic bar with a force,P,acting along its longitudinal axis in the direction such that it tends to elongate the bar.Such a force is referred to as an axial tensile load,and we can readily imagine it trying to pull the fibers apart and to cause failure on a transverse plane.It is safe to assume that all fibers of the bar,in regions remote from the point of application of the load ,are being pulled apart with the same load intensity.With this assumption,the load intensity or stress is uniform on a transverse plane and is given by
= (4-1)
When P is in Newtons and A is in square metres,stress,,is in Newtons per square metre ( N/rn2 ) ,which is by definition Pascals( Pa).
For a given axial load and given dimensions,the stress can be calculated from( 4-1 ) and compared with the stress that can be safely carried by the material ...The safe stress,known as the design stress or allowable stress,is determined by tests performed on material made to the same specifications as the part being considered.A safety factor,frequently imposed by a legally established code,is applied to the strength,as determined by tests,to give the allowable stress.
The allowable stress,,give by
= (4-2)
where is the stress at which the material fails( failure to be defined later) and n is the safety factor.
Before approving trial dimensions,the designer makes certain that the design is safe by determining that the inequality
≥
or
≥ (4-3)
is satisfied.The inequality is usually more convenient in the form
≥ (4-4)
It might at first seem that the designer would always dimension the cross section that the stress would exactly equal the allowable stress.However,it may be very costly to produce .parts that have nonstandard sizes,so it is usually more economical to waste some material by selecting the next larger standard size above that required by the allowable stress.Departure from standard sizes is justified in cases where the penalty for excess weight is very severe,as in aircraft or space-ship design.
中间读不出来的符号可以省略不译

在解释设计循环过程时,一个极其简单的构件需要首先进行界定.这个构件就是所谓的等截面杆,即一个力P沿着其纵轴作用并因此导致这个杆的延长.这样的一个力被认为是一类轴向的弹性负荷,我们可以想象这样的力使得纤维撕裂和横向平面的变形失效.显然地,杆上距离负荷作用点较远的纤维被同等强度的负荷所拉扯分开.在这一的假设下,负荷的强度和压力在横向平面上是一致的,并由（4-1）公式给出具体计算.公式中力P单位为牛顿,面积A单位是平方米,压强单位是帕斯卡.
在给定的轴向负荷和给定的面积,压强可以通过公式（4-1）计算,并可以与材料承受的安全压力相比较.安全压力,即设计承压或者可承受压力,可以通过一致规范下的对特定材料的实验确定.其中的一项安全因素,一般由法律指标所规定,被应用至实验确定的压力中,来给出上述的可承受压力数值.
可承压数值可以由公式（4-2）给出,其中 表示材料破坏的力的大小,n指的是上面提到的安全因素.
在确定实验面积前,设计者必须通过不等式（4-3）和（4-4）确定这个设计的安全性能.
设计者应该测量横截面面积来保证负荷恰好达到可承压力.但是可能获得非标准零件会十分昂贵,因此如果选择更大的标准零件（大于可承压力要求的面积）并除去部分材料来作为实验材料会更加经济节约.标准零件的偏差需要被矫正,以防止因为超重造成的严重惩罚,比如在飞机以及航天器的设计过程中.
我觉得中间读不出来的部分应该是公式吧,整体上来说还是完整的,如果有上下文就更好了,