Microscopic fatigue processes in a plain-weave glass-fibre composite

This paper focuses on the microscopic damage and progressive failure of a composite reinforced by plain-weave glass cloth under tensile fatigue loading. The fatigue process was divided into three stages like that of multi-directional laminates. It was found that the internal damage at each stage (matrix cracks, debonds in the weft, successive debonds in the warp and ‘metadelaminations’ between warps and wefts) occurred near the cross-over point of the fabric. The modulus decay mechanism was explained by considering the progression of this internal damage. From the end of the first stage to the beginning of the middle stage, a characteristic damage state (CDS) (called a ‘meta-CDS’) was observed. It was found that woven composites have a unit area of damage accumulation (called a ‘unit cell’) and the damage of each unit cell and its distribution control the total fatigue damage of the material.     

Rene′95粉末合金喷丸强化研究

研究了Ｒｅｎｅ′９５热等静压粉末高温合金喷丸后的残余应力场、组织结构、致密度及其与疲劳性能的关系。结果指出，喷丸强化能够有效地提高合金高周和低周疲劳强度。     

MICROSTRUCTURE AND FATIGUE PROPERTIES OF A WELDED DUPLEX STAINLESS STEEL

Abstract— In response to the increasing structural applications in duplex steels for welded structures, fatigue behaviour of a SAF 2304 grade duplex stainless steel was investigated, considering both the base metal and GTAW welded joints. Fatigue curves and fatigue limits under rotary bending fatigue were obtained. The study focused attention on the microstructural features of fatigue crack propagation of the two series of experiments, thereby permitting an evaluation of the tortuous crack path of welded joints and the mechanisms related to threshold microstructural barriers.     

涂层材料的断裂分析(英文)

和基体厚度相比,涂层很薄,因此细观力学模型可把基体作为半无限弹性体。由于涂层和基体材料的膨胀系数及弹性系数不匹配,涂层材料中残余热应力的解析解为 E_c/(1-γ_c)·(α_s-α_c)△T。用有限元法校核,该应力和解析解吻合得好。通过对涂层产生裂纹驱动力和断裂韧性的讨论,提出了抗裂涂层厚度公式。     

Fatigue behaviour of a phenolic matrix composite

This paper presents results of a fatigue life investigations carried out in plate specimens of a fibre-glass-reinforced phenolic matrix composite. Tensile and Young's modulus data were obtained at four different testing temperatures (room temperature, 100, 150 and 200 °C). The fatigue S−N data were obtained at room temperature only and for two stress ratio values (R=0 and 0.4). Fatigue and tensile behaviour was assesesed in the composite with the fibres aligned in the longitudinal loading direction. The results were obtained for two values of volume fraction (0.28 and 0.42) and three different glass surface treatments. A detailed comparison of fatigue results is given taking into account several fatigue parameters and also the testing variables. Results of observations of SEM fracture surfaces are also presented.     

弱凝胶调驱降维数值模拟方法研究

目前用于弱凝胶调驱的化学驱软件大多存在计算速度慢、数值弥散现象严重的问题,为了提高弱凝胶调驱数值模拟的速度和精度,提出了降低维数的模拟方法。利用追踪流线的方法,将弱凝胶调驱的三维渗流问题,转化为沿流线计算饱和度的一维问题,大大降低了求解饱和度方程组中方程的数目,从而提高了计算速度。利用该方法,模拟了玉门老君庙油田一个试验井区的水驱开发历史,优化了弱凝胶调驱的注入浓度、注入速度及注入体积等参数,并预测了弱凝胶调驱的动态,预测该方案可提高采收率7.6%。     

红外焦平面器件脉冲驱动电路的小型化设计

代表着红外器件发展的主流方向的红外焦平面器件，其正常工作时需要驱动脉冲信号多达十几路，为了使红外焦平面阵列处于最佳工作状态，就必须设计出相应的驱动电路。提出了一种红外焦平面器件驱动电路的设计方法。该电路具有体积小、功率低及灵活性好等特点，为驱动电路以及成像系统的小型化提供了良好的技术基础。     

MOS功率驱动高速脉冲激光器的研究

运用经典电路理论,对MOS功率管的开关特性、驱动原理进行了分析,导出了应用MOS功率管实现高速大电流开关应遵从的原则和方法,并成功地实现了光脉冲上升时间小于5ns、下降时间小于10ns,驱动电流达10～50AP-P激光器电源的要求.     

Thermal—Mechanical Fatigue Behavior and Life Analysis of Cast Ni—base Superalloy K417

In-phase(IP) and out-of-phase(OP)thermal-mechanical fatigue(TMF) behavior of cast Ni-base superalloy K417 was studied.All experiments were carried out under total strain control with temperature cycling between 400-850℃.Both in-phase and out-of-phase TMF specimens exhibited cyclic hardening followed by cyclic softening at the minimum temperature.Besides,they cyclically hardened in the early stage of life followed by cyclic softening at the minimum temperature.Besides,they cyclically hardened in the early stage of life followed by cyclic softening at the maximum temperature.OP TMF life was longer than of IP TMF.Various damage mechanisms operating in different controlled strain ranges and phasing were discussed.A few life prediction methods for isothermal fatigue were used to handle TMF fatigue and their applicability to superalloy K417 was evaluated.The SEM analysis of the fracture surface showed that transgranular fracture was the principal cracking mode for both IP and OP TMF.Oxidation was the main damage mechanism in causing shorter fatigue life for IP TMF compared with OP TMF.