机械专业英语7.pptVIP

单词复习： concurrent engineering design deem Integral reciprocating motion/ circular motion internal combustion?engine Accreditation Board for Engineering and Technology modern design theory and methodology;Lesson 7 Engineering Design and safety factors 工程设计和安全系数;Paragraph 1; Murphy’s Law: If any material can fail, it will. Laws of materials applications (1) All materials are unstable. (2) The materials system is only as strong or as stable as its weakest or most unstable component. 墨菲法则：如果任何材料有可能出问题，它（系统）终将出问题。 材料应用法则：（1）任何材料都是不牢固的；（2）材料系统的强度和牢固程度仅仅像它最薄弱的、最不牢固的部分。 ;Paragraph 2: ;Under stress(应力， strain 应变), all materials respond to that stress. Creep(蠕变) is an example. Given enough time, failure(失效) can be calculated to occur in all materials under creep stress. 在压力作用下，所有材料都会有变化。蠕变(creep)是一个例子。在蠕变压力作用下，若有足够的时间，所有材料一定会产生屈服。 ;Creep deformation蠕变变形;Stress and environment can act in concert to cause failure, for example, stress corrosion cracking. Creep-temperature effects and stress-temperature effects can contribute to the degradation of properties and components and system failure. 压力和环境共同（in concert）作用会造成屈服，例如，应力腐蚀裂纹。蠕变温度影响和应力—温度影响都会导致性能降低、零件和系统失败。 ; The design processParagraph 3:;The design cycle can involve the original thoughts, sketches, and knowledge that in the specification stage produce engineering drawings. 设计循环涉及最初的构想、草图、在详细描述阶段绘制工作图的知识。 Computer-aided design (CAD, CAM计算机辅助制造) is now employed to implement a cycle in which various designs or design ideas may be tested or simulated. 计算机辅助设计现在已用于设计过程，各种设计和设计思想能被检验和仿真。 ;Paragraph 4:;Prior to a fabrication step, materials specifications must be made depending upon the design requirements. 在制造之前必须依据设计要求给出材料的技术要求（specification）。 ;These may have to be altered in the design simulation if the requisite properties cannot be identified in existing materials, or fabrication may have to delay until new materials can be designed and fabricated. Materials are the reality in a design.