Effect of crack-growth mechanism on the prediction of fracture load of adhesive joints

This paper presents observations regarding the cracking behavior of tensile-loaded structural adhesive joints. Experiments showed that fracture occurred by the development and propagation of a damage zone, rather than a single, sharp crack, and that the presence of the adhesive spew fillet did not affect the fracture load of the adhesive joints studied. For joints bonded with the mineral-filled epoxy Cybond 4523GB (American Cyanamid), there was approximately 5 mm of subcritical crack propagation prior to final fracture. Fracture-load predictions based on the initial uncracked geometry made in previous papers were unaffected by this small change in geometry. For joints bonded with the rubber-toughened epoxy Permabond ESP 310, approximately 50 mm of subcritical crack propagation was observed. It was again found that predictions made in previous papers on the basis of the initial geometry gave a good estimate of the final fracture load even though this subcritical crack propagation significantly altered the geometry, and thus the applied energy release rates. The effect of shear deformations of the adherends was also investigated, and it was found that shear deformations could be neglected in engineering calculations for joints subject to remote tensile loading.     

转向柱管承载能力的试验研究

在分析转向柱管花键部位应力集中情况的基础上,通过对某厂生产的转向柱管扭转破坏的试验研究,得到如下结论:①转向柱管的承载能力与其外花键齿与方向盘中心内花键齿之间的非接触区长度有关,以花键端部过渡圆弧的直径大小为宜;②安装方向盘总成时所施加在安装螺母上的拧紧力矩在70N.m左右时,转向柱管的承载能力最大。     

孔型热轧时轧制力的实用计算公式

采用修正系数法,利用板材在带刻槽的冲头进行深冲与平面冲头下深冲时的接触压力的比值确定孔型影响系数,进而推导出孔型热轧时轧制力的实用计算公式.     

结构化P2P网络中基于流言传播的负载均衡

提出了结构化P2P网络中利用结点间周期性的拓扑维护通信来夹带、传播消息进行负载均衡的方法，具体针对Chord系统从消息传播的速度和规模两个方面分析了该方法的性能，并利用仿真进行了验证。讨论了结论在其它形式网络中的推广和实现中的消息管理问题。     

The Benefits of a "Sidelong" Approach to Self-Esteem Need Satisfaction: Comment on Crocker and Park (2004).

J. Crocker and L. E. Park (2004) have achieved an admirable integration of the self-esteem literature with their claim that self-esteem is better conceived of as a dynamic human striving, rather than as a passive state or personality characteristic. However, the costs of self-esteem striving may be overstated--these costs may arise only in certain constrained cases. Also, although Crocker and Park suggested that self-esteem is not a true psychological need, there is evidence that humans in all cultures need to feel a positive sense of self-worth (K. M. Sheldon, in press). Problems may arise only when people strive too directly for this feeling, rather than deriving it as a natural concomitant of non-self-focused goals. A "sidelong" approach to self-esteem need satisfaction is advocated in this commentary. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

固定式塔吊基础设计与施工技术

潘家园小区工程建筑面积3．6万m^2，地下3层，地上28层。基槽标高-10.750m，地面至屋面女儿墙上口高度为83m，地上标准层层高2．8m。采用土钉墙护坡，坡度1：0．1，该工程的地质条件适宜桩基础的施工。     

无粘结预应力卵形消化池的受力分析及设计

本文采用有限元计算分析软件ANSYS对近年来出现的卵形消化池进行计算分析,着重对卵形消化池在多种荷载下的内力与变形进行分析,并采用二次曲线模拟沿高度均匀变化的壁厚。提出适合卵形消化池结构预应力钢筋等效为均布荷载的计算与配筋方法,取得较好的结果。     

Effect of load ratio on the deformation behaviour of fatigue crack tips

To investigate the change in the manner of plastic deformation at a fatigue crack tip under different loading conditions, the fresh surface area which is produced in one fatigue cycle at the crack tip was measured by an electrochemical method under various load ratios. The fresh surface area produced in each fatigue cycle is in proportion to the crack propagation rate in the Paris regime. This indicates that the crack tip geometry at K_max maintains a similar profile through the Paris regime. Furthermore, the fresh surface area is independent of load ratio at a given da/dN in the Paris regime. This suggests that the shape of the fatigue crack tip at K_max should be independent of load ratio at a given da/dN, and that the shape at K_min is also independent of load ratio, whereas the size of the deformed region at the crack tip is in proportion to da/dN.     

分布式协作工作流技术研究

工作流是实现企业业务过程建模、优化、管理、集成和自动化的核心技术．作为分布式的应用平台，工作流管理系统任务处理能力即吞吐能力是一个重要的性能指标．目前，已有的工作流管理系统在这方面存在较大的不足，成为工作流管理系统广泛应用的严重障碍．本文研究了工作流系统的协作方式和负载平衡技术，定义了工作流系统的负载因子，给出了一个分布式协作工作流系统模型，并结合业务流程逻辑，提出了分布式协作工作流系统负载平衡调度算法．实验表明该分布式协作工作流系统有效地扩展了单个工作流系统的吞吐能力。     

集中载荷作用下的套管抗挤能力分析

根据油田套管损坏情况,建立了集中载荷作用下的套管抗挤能力计算模型,利用能量法和曲杆理论,分析研究了承受180°对称分布集中载荷、90°均匀分布集中载荷和120°均匀分布集中载荷下中厚壁套管抗挤能力,得出了理想圆管抗挤强度和套管屈曲临界挤毁压力的计算公式,通过分析比较理论解与有限元解,其最大相对误差不超过1%,得出了套管抵抗局部载荷的能力低于抵抗均布载荷的结论。