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t an optimal construction under different constraints. Design sensitivity analysis putes the rates of change of structural responses with respect to changes in design parameters. These design parameters are usually referred to as design variables and can be used to represent shell thickness, beam cross sectional dimensions, journal bearing sizes, and so on. Design optimization analysis is a formal plan or algorithm, that is used to search for a “best” design. Such as in automotive chassis design, we may want to investigate changes in cabin resonant frequencies given changes in panel thickness. These 共 5 頁 第 9 頁 rates of change are called design sensitivity coefficients. once these rates of change are known, optimization analysis can find the optimal set of panel thickness which yield the lowest level of cabin resonant frequencies. The other example: one part of vehicle’s frame structure was found to be overstressed. Unfortunately, it is too expensive to redesign that particular frame ponent at this stage in the engineering cycle. However, other structure ponent nearby can be modified without severe cost increases. There are nearly 90 structure design parameters can be manipulated. The design goal is to reduce the magnitude of the stresses by reducing the internal load to the overstressed member. 共 5 頁 第 10 頁 指 導(dǎo) 教 師 評(píng) 語 外文翻譯成績: 指導(dǎo)教師簽字: 年 月 日 注: 1。不幸的是,它太昂貴 而不能在 設(shè)計(jì)階段 就發(fā)現(xiàn)。如在汽車底盤設(shè)計(jì)中,我們可能要調(diào)查面板厚度變化 、車身 共振頻率的變化。 汽車的設(shè)計(jì)目的是 在 不同的約束下的最佳 效果 。實(shí)現(xiàn) 這一目標(biāo) 是在 早期發(fā)展階 段的設(shè)計(jì)工作,數(shù)值模擬的工具越來越多地使用的代名詞。 內(nèi)部 噪音問題,大 多數(shù) 聲能在一個(gè)典型的汽車是低于 125赫茲 。 表 1 理論與實(shí)驗(yàn)結(jié)果實(shí)驗(yàn)結(jié)果基本一致 分析結(jié)果 實(shí)驗(yàn)結(jié)果 誤差 % % % % 發(fā)動(dòng)機(jī)罩和行李箱蓋必須有足夠的抗扭剛度,門和外板 也 必須有足夠的剛度, 其他,例如 鏡 子、 轉(zhuǎn)向系統(tǒng) 、 排氣 、 必須有合理的動(dòng)態(tài)特性, 同時(shí) 避免 車架頻率, 因此 必須錯(cuò)開發(fā)動(dòng)機(jī)激發(fā)頻率 。 以上是車身裝配完的頻率范圍。在中國,速度低于 150km/h,從而頻率低于 21Hz。車身固有頻率必須錯(cuò)開激發(fā)頻率。主體結(jié)構(gòu)與懸架,發(fā)動(dòng)機(jī),車身附件等之間的剛度分析要加以重視。對(duì)于靜態(tài)強(qiáng)度分析,安全系數(shù)為 。但大多數(shù)情況下有兩種類型,如下: ( 1)扭轉(zhuǎn)(模仿車輪高速轉(zhuǎn)動(dòng))扭矩的大小取決于軸載荷,懸臂梁的剛度以及負(fù)載表面的粗糙度。通過有限元分析方法我們能滿足汽車設(shè)計(jì)的要求和基本的研發(fā)設(shè)計(jì)。 眾所周知,汽車車身結(jié)構(gòu)非常復(fù)雜。 然后進(jìn)行正常的模