机械工程专业英语-施平-没翻译课文补充VIP免费

机械工程专业英语- 施平 - 没翻译课文补充2 ————————————————————————————————作者：————————————————————————————————日期：3 4、工程机械概述As we look around us we see a world full of “ things” : machines, devices, tools; things that we have designed, built, and used; things made of wood, metals, ceramics, and plastics. We know from experience that some things are better than others; they last longer, cost less, are quieter, look better, or are easier to use. ;;情况 . Ideally, however, every such item has been designed according to some set of “functional requirements” as perceived by the designers — that is, it has been designed so as to answer the question, “ Exactly what function should it perform?” In the world of engineering, the major function frequently is to support some type of loading due to weight, inertia, pressure, etc. 的From the beams in our homes to the wings of an airplane, there must be an appropriate melding of materials, dimensions, and fastenings to produce structures that will perform their functions reliably for a reasonable cost over a reasonable 4 lifetime. In practice, engineering mechanics methods are used in two quite different ways: (1) The development of any new device requires an interactive, iterative consideration of form, size, materials, loads, durability, safety, and cost. (2) When a device fails (unexpectedly) it is often necessary to carry out a study to pinpoint the cause of failure and to identify potential corrective measures. Our best designs often evolve through a successive elimination of weak points. 1.cost. 2.To many engineers, both of the above processes can prove to be absolutely fascinating and enjoy...