滚子链材料疲劳强度分布函数的研究

对常用滚子链链板材料进行成组疲劳试验，得到材料在不同预期寿命下的强度分布，着重对数据处理过程中的诸多问题进行解析，为链条产品的可靠性设计提供了重要基础数据。

钢球—外锥轮式无级变速器传动锥轮的可靠性设计

本文根据传动锥轮的工作应力和材料疲劳强度 ,采运用可靠性设计的理论 ,建立起锥面传动功率、锥轮直径与材料疲劳寿命及可靠度等因素之间的关系 ,为传动锥轮的可靠性设计计算提供一种参考。

Effect of stress level on fatigue behavior of 2D C/C composites

Laminated carbon fiber clothes were infiltrated to prepare carbon fiber reinforced pyrolytic carbon （C/C） using isothermal chemical vapor infiltration （CVI）. The bending fatigue behavior of the infiltrated C/C composites was tested under two different stress levels. The residual strength and modulus of all fatigued samples were tested to investigate the effect of maximum stress level on fatigue behavior of C/C composites. The microstructure and damage mechanism were also investigated. The results showed that the residual strength and modulus of fatigued samples were improved. High stress level is more effective to increase the modulus. And for the increase of flexural strength, high stress level is more effective only in low cycles. The fatigue loading weakens the bonding between the matrix and fiber, and then affects the damage propagation pathway, and increases the energy consumption. So the properties of C/C composites are improved.

Fatigue crack growth mechanism in cast hybrid metal matrix composite reinforced with SiC particles and Al_2O_3 whiskers

The fatigue crack growth(FCG) mechanism of a cast hybrid metal matrix composite(MMC) reinforced with SiC particles and Al2O3 whiskers was investigated. For comparison, the FCG mechanisms of a cast MMC with Al2O3 whiskers and a cast Al alloy were also investigated. The results show that the FCG mechanism is observed in the near-threshold and stable-crack-growth regions.The hybrid MMC shows a higher threshold stress intensity factor range, ?Kth, than the MMC with Al2O3 and Al alloy, indicating better resistance to crack growth in a lower stress intensity factor range, ?K. In the near-threshold region with decreasing ?K, the two composite materials exhibit similar FCG mechanism that is dominated by debonding of the reinforcement–matrix interface, and followed by void nucleation and coalescence in the Al matrix. At higher ?K in the stable- or mid-crack-growth region, in addition to the debonding of the particle–matrix and whisker–matrix interface caused by cycle-by-cycle crack growth at the interface, the FCG is affected predominantly by striation formation in the Al matrix. Moreover, void nucleation and coalescence in the Al matrix and transgranular fracture of SiC particles and Al2O3 whiskers at high ?K are also observed as the local unstable fracture mechanisms.However, the FCG of the monolithic Al alloy is dominated by void nucleation and coalescence at lower ?K, whereas the FCG at higher ?K is controlled mainly by striation formation in the Al grains, and followed by void nucleation and coalescence in the Si clusters.

Preparation of porous Ti35Nb alloy and its mechanical properties under monotonic and cyclic loading

The Ti-35%Nb(mass fraction) foams were prepared by a powder metallurgy method,and the microstructure and the mechanical properties of the foams under monotonic and cyclic loading were investigated.The microstructure of the foams mainly consists of β phase,and the foams exhibit the homogenous pore distribution with the average pore size of 252 μm.The foams with 66% porosity show a typical stress-strain curve of the open-cell foams,and the plateau stress is about 56 MPa.The fatigue strength of the foam is 15.12 MPa at 107 cycles.The fractographic analysis of the foams reveals that the cracks nucleate within the struts and grow in a fatigue mechanism,resulting in the acceleration of the fatigue damage of the foams.

抛丸板、酸洗板与电泳涂装工艺配套后的耐盐雾对比

与酸洗除锈工艺相比，抛丸除锈工艺具有无氢脆、不发生过蚀、提高材料疲劳强度、没有刺鼻性气味、不伤害皮肤、没有酸污染等优点。但抛丸除锈使工件表面粗糙度大大增加，造成电泳漆膜在烘干流平时微观边缘漆膜厚度偏薄，可能会影响漆膜的耐腐蚀性能。为此，对车架用热轧钢板抛丸，做成不同粗糙度的试板后进行电泳涂装，并与酸洗除锈后电泳涂装的试板做漆膜的耐盐雾对比试验。