共查询到10条相似文献,搜索用时 78 毫秒
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过盈配合和预紧力的混合作用对复合材料机械连接结构的影响及其机制 总被引:1,自引:0,他引:1
为研究钉孔过盈配合情况和紧固件预紧力及二者混合作用对复合材料连接强度的影响及其机制,提出了一种基于试验验证的有限元方法,在有限元模拟结果与两组不同配合复合材料与钛合金单剪双钉连接拉伸试验吻合良好的基础上,进一步模拟6种不同螺栓预紧力和7种不同钉孔配合模式的组合,共42种不同情况的结构承载能力。通过对模拟结果的分析发现:一定的干涉配合值和预紧力虽然可能导致钉孔周围在受载较小时提前出现较小破坏,但在载荷较大时反而可以改善孔周的接触条件,从而减小孔周的纤维破坏范围,并最终提高连接结构的破坏载荷。而且钉孔配合情况和螺栓预紧力对连接结构承载能力会相互影响,即在不同钉孔配合情况下所得到的紧固件预紧力优化值会有所不同,反之亦然。因此在进行复合材料机械连接结构承载能力优化时,必须同时考虑不同参数的影响,才能获得最优的结构设计。 相似文献
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In this work, a hybrid composite journal bearing (HCJB) composed of carbon/phenolic laminated composite bush and steel housing was designed for marine vessels because the composite journal bearing reduces the possibility of the seizure problem between the journal and bearing. The two components of bearing were assembled by interference fit joining method and a series of durability tests were conducted using the laboratory bench with the lubricants of SAE 30 oil, water, and sea water. That the HCJB was found reliable under the interference fitting loads and environmental temperature change. 相似文献
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Process capability indices are useful tools for evaluating the ability of a process to produce products that meet certain specifications. The assembly quality is dependent on the distribution of variations of assembly dimensions, which is in turn dependent on mating conditions in the mechanical assembly. Since it is often difficult to measure the assembly dimensions in the production stages, they are not considered as a direct inspection objective. Rather, the inspection and evaluation of quality is carried out by specifying whether the assembly requirements satisfy the specified limits. Therefore, we can basethe process capability indices on the assembly dimensions. In most real life cases, the observations are fuzzy. In this paper, a novel method based on fuzzy concepts for process capability analysis of assembly dimensions in mechanical assemblies is presented. According to this scheme, sample observations of manufactured variables are described as fuzzy numbers. The proposed method is able to estimate the ability of the manufacturing process in satisfying the assembly quality in the mechanical assemblies with asymmetric tolerances which have non-normal distributions. In this paper, a proper criterion based on the probability of fuzzy set to interpret the computed fuzzy results is proposed, so these results are converted to the interpretable results for making a decision to evaluate the assembly quality. Furthermore, a new fuzzy-based quantity factor for expressing the percent contributions of effective manufacturing variables on the assembly quality is presented. The application of the presented method is demonstrated through an example and its results are discussed. 相似文献
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Kazuto Yamauchi Kikuji Hirose Hidekazu Goto Kazuhisa Sugiyama Koji Inagaki Kazuya Yamamura Yasuhisa Sano Yuzo Mori 《Computational Materials Science》1999,14(1-4):232-235
Interactions between ultra-fine powder [SiO2] and work [Si (1 0 0) surface] in EEM (Elastic Emission Machining) has been investigated by employing first-principles molecular dynamics (MD) simulations. Calculated results show the possibilities of the atomic removal through the solid phase chemical interaction between surfaces of ultra-fine powders and works. 相似文献
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High-shear wet granulation is a complex process that in turn makes scale-up a challenging task. Scale-up of high-shear wet granulation process has been studied extensively in the past with various different methodologies being proposed in the literature. This review article discusses existing scale-up principles and categorizes the various approaches into two main scale-up strategies – parameter-based and attribute-based. With the advent of quality by design (QbD) principle in drug product development process, an increased emphasis toward the latter approach may be needed to ensure product robustness. In practice, a combination of both scale-up strategies is often utilized. In a QbD paradigm, there is also a need for an increased fundamental and mechanistic understanding of the process. This can be achieved either by increased experimentation that comes at higher costs, or by using modeling techniques, that are also discussed as part of this review. 相似文献
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The burn-in test time is an important parameter of the complex batch processing machine scheduling problem. The omission of the loss of quality deviations in manufacturing generates a non-comprehensive and imperfect result in the optimisation of burn-in time, which hinders the identification of proactive and economical optimisation strategies to prevent infant failure in manufacturing. To solve this problem, this study visualises and quantifies for the first time the hidden loss caused by quality deviations in manufacturing and uses it as a newly added constraint to optimise the burn-in time. Firstly, a quality loss model composed of visible yield loss and warranty costs related to measurable but undetectable reliability vulnerabilities is defined. Secondly, the loss effects of growing defects are measured during the burn-in test, and the optimal burn-in time expressed by the proposed quality loss model is traded off between the additional burn-in cost and the decreased quality loss for an acceptable low infant failure rate. Finally, the effectiveness of the proposed optimisation approach is demonstrated using actual data from a control board with a high infant failure rate. Results show that the proposed method can systematically combine the fundamental loss of quality deviations in the optimisation of burn-in time, which supplements the commonly used optimality criteria, with the upstream loss of quality deviations in the form of manufacturing defects. 相似文献
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This paper investigates the quality of environmental impact statements (EISs) and gives us an understanding about the performance of environmental impact assessment (EIA) practice in Bangladesh. EIA has been formally practised in Bangladesh since 1995.However, no study has yet been conducted on the quality of EISs. This study fills this gap. This empirical study shows that the quality of EISs in Bangladesh is ‘just satisfactory’ only. A significant proportion of EISs (34%) are still unsatisfactory. Finally, possible factors affecting the quality of EISs are examined and measures to improve the quality of EISs are recommended. The findings will be useful to EIA practitioners and other stakeholders in Bangladesh. This study will also provide a general guideline for other developing countries with similar socio-economic context. 相似文献