影響耐久性強(qiáng)度的因素外文翻譯-免費(fèi)閱讀
【正文】 參考文獻(xiàn) 8 顯示了用于 分析這些數(shù)據(jù)的方法。 我們不會(huì)直接用圖 510 來(lái)解決這本書里的問(wèn)題，因?yàn)槲覀児浪銣?zhǔn)確的耐力強(qiáng)度的程序是由圖 59來(lái)開始計(jì)算的，此圖體現(xiàn)了從逆向彎曲試驗(yàn)中得出的數(shù)據(jù)。（見參考文獻(xiàn) 2 第 27 頁(yè)）回想一下，在彎曲旋轉(zhuǎn)軸，如圖 52 所示是一個(gè)遭受了應(yīng)力比 R=1 負(fù)載的例子 平均波動(dòng)與壓縮應(yīng)力就如部分顯示應(yīng)力（ c）和（ d）。這種現(xiàn)象的一個(gè)可能的解釋是，鑄造材料很可能擁有比鍛造材料更各向同性的材料性能和較少受到應(yīng)力集中的影響。腐蝕可能導(dǎo)致有害的局部表面粗糙度，也可以改變內(nèi)部晶粒結(jié)構(gòu)和外置式換熱器材料化學(xué)性質(zhì)。 本科生畢業(yè)論文（設(shè)計(jì)） 第 14 頁(yè) 共 17 頁(yè) 本科生畢業(yè)論文（設(shè)計(jì)） 第 15 頁(yè) 共 17 頁(yè) 殘余應(yīng)力 疲勞破壞通常開始在相對(duì)較高的拉應(yīng)力的位置。 F(72176。對(duì)于平面，軋制鋼， 應(yīng) 考慮 厚度 ，指出 這些方程組采用 的 近似。 這個(gè)討論涉 及到對(duì)僅受正應(yīng)力的材料拉伸強(qiáng)度的 耐久性 ，也就是拉應(yīng)力造成的彎曲的行動(dòng)或軸向張力。R= ■ Partially reversed fluctuating stress with a tensile mean stress【 Figure 54(b)】 。C) will reduce the endurance strength of most ductile materials. Nonuniform Material Properties Many materials have different material properties in different directions because of the manner in which the material was sheet or bar products are typically stronger in the direction of rolling than they are in the transverse 本科生畢業(yè)論文（設(shè)計(jì)） 第 4 頁(yè) 共 17 頁(yè) direction. Fatigue tests are likely have been run on test bars oriented in the stronger of such material in the transverse direction may result in lower endurance strength. Nonuniform properties are also likely to exist in the vicinity of welds because of inplete weld peration,slag inclusions,and variations in the geometry of the part at the weld. of heattreated materials may alter the strength of the material because of local annealing near the weld. Some welding processes may result in th production of residual tensile stresses that decrease the effective endurance strength of the material. Annealing or normalizing after welding is often used to relieve these stresses,but the effect of such treatments on the strength of the base material must be considered. 本科生畢業(yè)論文（設(shè)計(jì)） 第 5 頁(yè) 共 17 頁(yè) 本科生畢業(yè)論文（設(shè)計(jì)） 第 6 頁(yè) 共 17 頁(yè) Residual Stresses Fatigue failures typically initiate at locations of relatively high tensile and machining,especially with high material removal rates,also cause undesirable residual tensile has already been mentioned as a process that may produce residual tensile stress. Any manufacturing process that tends to produce residual stress will decrease the endurance strength of the ponent. Critical areas of cyclically loaded ponents should be machined or ground in a gentle that produce residual pressive stresses can prove to be blasting and peening are two such blasting is performed by directing a highvelocity stream of hardened balls or pellets at the surface to be uses a series of hammer blows on the ,springs,and other cyclically loaded machine parts can benefit from these methods. Corrosion and Environmental Factors Endurance strength data are typically measured with the specimen in conditions that expose a ponent to water,salt solutions,or other corrosive environments can significantly reduce the effective endu
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