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AbstractThe Poisson’s ratio is a fundamental and inherent property of the materials in their reaction to loading. Determining the correct value of the Poisson’s ratio leads to more accurate predictions of the mechanical behavior of the material, especially in employing mechanical or numerical finite element modeling methods. In this study, seven different types of medium and coarse yarn were digitally filmed in seven sections from three various angles while tensile strength testing. Then, longitudinal and transverse strains and consequently, momentary deformation index and Poisson’s ratio of the yarns were calculated. Significance level of the mean Poisson’ ratio was also determined at different angles and sections using statistical comparison test. The results showed that the transverse strain has a convergent state at the end of the test and the start of the yarn breaking occurs at the convergence point. Additionally, in upper sections of yarn near to the movable jaw of the strength tester, the amount of the longitudinal strain increases which leads to reduce in momentary deformation index and Poisson’s ratio of the yarn. Moreover, a sectional mode to measure the Poisson's ratio was presented. 相似文献
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Youcef Djebloun Mabrouk Hecini Tarek Djoudi Belhi Guerira 《Journal of Natural Fibers》2019,16(3):357-367
The present study is an attempt to valorize local vegetable fibers by evaluating thire effectiveness as a new composite biomaterial. Our aim was to determine the mechanical characteristics, namely the elastic modulus and Poisson’s coefficient, of a fiber, locally called “Lif,” that is a natural material extracted from different date palm tree varieties in Biskra, a region situated in southeastern Algeria. This study compares the mechanical characteristcs of the Lif date palm tree fiber with other synthetic and plant fibers studied previously. 相似文献
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Hongling Wen Liu Liu Xinlong Yan 《Quality and Reliability Engineering International》2021,37(5):1956-1964
Exponentially weighted moving average (EWMA) control chart has a significant effect in improving product quality and is widely used in various fields. In addition to continuous data, there are many Count Data in life that need to be monitored. Poisson distribution is one of the models that study the probability distribution of discrete data, and has a wide range of applications. In previous monitoring, it was considered that the mean value of Poisson distribution in normal state was a constant value after it was determined. But in the actual situation, there are many unavoidable objective conditions that will affect the final results. We cannot monitor all situations according to the same criteria. If we ignore the conditions that affect the occurrence of the event and directly monitor the final result, on the one hand, it will increase the probability of false alarms from the control chart. On the other hand, the control chart will not be able to detect problems in time due to the untimely update of conditions. In response to this situation, this paper proposes a regression-adjusted EWMA control chart to monitor the Poisson process. The control chart can continuously adjust and update the expected values according to the actual situation. It can make the monitoring process more reasonable and the monitoring results more valuable. 相似文献
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灌芯砌体的变形性能试验研究 总被引:2,自引:0,他引:2
系统地研究了灌芯砌体的变形性能 ,对灌芯砌体的受压和受剪变形进行了试验研究。提出了灌芯砌体的受压和受剪本构关系 ,根据试验研究成果还给出了弹性模量、泊松比和剪变模量的计算公式 ,为灌芯砌体结构的应用提供了理论依据。 相似文献
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研究宏观等效泊松比和弹性模量。首先通过解析方法,推导空心板作为双向肋板的泊松比的计算公式。其次根据应力分布特点,提出圆孔空心板横管向弯曲、轴压弹性模量的有效截面计算方法,确定竖向倾角0α=22.5°的孔半径所在水平线为有效截面的边界线,并给出计算公式。此外研究还发现,双向肋板中存在横肋引起刚度增大的“横肋效应”现象,给出该现象的量化表达式。所提方法和公式均通过理论、数值验证,是现浇空心板结构计算的理论基础。 相似文献
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We propose an integer‐valued stochastic process with conditional marginal distribution belonging to the class of infinitely divisible discrete probability laws. With this proposal, we introduce a wide class of models for count time series that includes the Poisson integer‐valued generalized autoregressive conditional heteroscedastic (INGARCH) model (Ferland et al., 2006) and the negative binomial and generalized Poisson INGARCH models (Zhu, 2011, 2012a). The main probabilistic analysis of this process is developed stating, in particular, first‐order and second‐order stationarity conditions. The existence of a strictly stationary and ergodic solution is established in a subclass including the Poisson and generalized Poisson INGARCH models. 相似文献
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