共查询到19条相似文献，搜索用时 265 毫秒
1.
《承德师专学报》1990,(4)
一,在材料力学实验中广泛使用电测技术材料力学实验除测定材料机械性能外,还有一些验证根据材料力学有关变形假设推出的应力、应变关系式的实验,如纯弯曲梁正应力的分布,圆轴扭转剪应力的测定,复合受力状态主应力的测定等.完成这些实验可以用多种测量方法,而我们选择了电阴应变测试技术.我们这样做是基于下述的考虑:1、在深入场矿对我校毕业生工作情况调查中,了解到分配到油田、工厂都会经常接触到高压容器、高压阀、管路等,这些设施在安装、检修、运行中有时要进行应力监测以保证安全.常规使用的监测手段是电阻应变测试.一般专科不开设实验应力分析课程,只在材料力学课程中对电测技术做简单介绍.为使我校学生能更好掌握这项技术,我们决定在材料力学实验中广泛采用电测方法来测取各项实验的应变. 相似文献
2.
《实验室研究与探索》2020,(4):33-36
基于平面假设,对纯弯曲条件下3层材料组成的层合梁的纯弯曲问题进行了理论分析,应用电测技术对2组不同材料组成的层合梁分别进行了测试。通过对测试点应变的理论值和实际实验测试值结果进行比较,验证了实验方法和理论解的正确性。对层合梁的实验测试和理论分析不仅适用于实际工程研究,同时也可作为材料力学中纯弯曲实验的扩展,进一步加深学生对中心轴和复合材料概念的认识,具有研究意义和实用价值。 相似文献
3.
环氧树脂在高应变率下的热粘弹性本构方程和时温等效性 总被引：2，自引：0，他引：2
在—20℃～100℃的温度范围内用SHPB实验技术研究了环氧树脂在高应变率(10~2～10~3s~(-1))和直到7.5％大应变下的粘弹性力学行为。提出了一个简单实用的非线性热粘弹性本构方程,并发现存在一种时温等效性。在加卸载全过程中,理论计算值与实验结果相当符合。 相似文献
4.
《实验室研究与探索》2013,(12)
对低碳钢材料带孔薄壁圆管试样采用逐级加载试验方法,得出其在室温下的单轴循环应力-应变本构关系。利用有限单元法对圆管试样进行弹塑性分析,采用Von Mises屈服准则、多线性随动强化模型,并结合试验获得的本构关系来定义材料的弹塑性特性。拉扭应变载荷加载在柱坐标下进行,采用一端固定,另一端加轴向位移与周向位移的方式。分别在纯拉、纯扭以及拉-扭比例加载下计算出应力应变场,获得不同受力情况下不同孔径尺寸试样在缺口处的应力应变分布。计算结果为多轴加载疲劳试验和复杂应力状态下工程零部件的疲劳寿命预测与分析提供基本数据。 相似文献
5.
《东南大学学报》2019,(4)
为了建立高延性水泥基复合材料(HDCC)在单轴拉伸荷载作用下的本构关系,指导HDCC的结构设计,在分析与总结现有单轴拉伸本构关系的基础上,基于理想弹塑性线性强化模型,以名义初裂点和名义最大应力点为控制点,提出了HDCC单轴拉伸双线性本构方程,结合5组HDCC单轴拉伸应力-应变曲线,进行了拉伸本构方程的应用示范与控制点关键参数的分析比较.结果表明:所提出的本构方程克服了现有模型在计算承载力时富余度不足或过高的问题;实测最大应力值大于名义值,两者之比为1.08～1.22;通过应变硬化阶段曲线的谷值点拟合直线所得到的软化点拉伸应变值大于或等于实测最大应力点的拉伸应变值,两者的比值为1.00～1.19. 相似文献
6.
拉伸试验是一个重要的材料力学试验,当杆件材料和截面一定时,拉伸过程的变形和受力满足一定的关系。本文针对低碳钢杆件拉伸问题,根据已有的实验结果,基于神经网络的优化算法原理,建立杆件拉伸过程本构关系公式,为再现实验过程和虚拟实验提供良好的条件。 相似文献
7.
45钢绝热剪切变形数值模拟 总被引：1，自引：0，他引：1
采用Ansys／Lsdyna对SHPB加载条件下不同热处理状态的45钢进行了2D数值模拟,数值重现了帽型试样高应变条件下的绝热剪切变形历程。计算中采用二维轴对称应变条件下的两种网格模型,材料本构方程采用热粘塑性Johnson-Cook本构关系,基于应力塌陷绝热剪切形成判据和等效应力-时间曲线分析了绝热剪切变形规律。计算结果表明,绝热剪切敏感性与加载速率和材料的组织结构密切相关。 相似文献
8.
以2A11铝合金材料为例，采用美国MTS公司生产的MTS810 Material Test system对棒材试样作简单拉伸试验。运用Matlab的多项式运算函数对拉伸试验真应力．自然应变曲线非线性均匀变形阶段进行拟舍，建立了真应力一自然应变本构方程；误差分析表明，精度较高。研究结果为铝舍金材料真应力一自然应变本构方程的建立提供了新的方法，对工程实际应用具有很好的指导意义和参考价值。 相似文献
9.
对“测定杨氏模量”实验的改进 总被引：1，自引：0，他引：1
李海江 《川北教育学院学报》1997,7(2):62-64
本对“测定杨氏模量”实验进行了改进。用读数显微镜替代光杠杆来测金属丝微小长度的变化。用具体实验数据对这两种方法的相对误差进行比较，从而得出这种改进的优越性。 相似文献
10.
正在苏科版九年级物理课本中,有以下几个电学实验(探究电流跟电压关系、电流跟电阻关系;伏安法测定值电阻、伏安法测小灯泡电阻、伏安法测小灯泡电功率),用传统方法复习这几个实验,学生在复习时容易混淆相关知识点。笔者经过多次尝试,发现用对比法比较这几个实验的异同点来复习,能起到事半功倍的效果。 相似文献
11.
基于数字图像相关方法(DIC),搭建了一套基于该方法的纯弯曲梁教学实验平台,并同时采用电测法和DIC法测试了梁的弯曲应变。结果表明,两种方法测试得到的应变值基本一致,表明DIC方法具有较高的测试精度,可以应用于工程力学实验的教学。该平台可以开拓学生的视野,并激发学生的实践能力,为培养新世纪的复合型实用人才提供平台基础。 相似文献
12.
The paper is to design and construct a coupled elasto-plasticity damage constitutive model for concrete. Based on the energy dissipation principle, the Hsieh-Ting-Chen four-parameter yield function is used. The model can reflect different strength characteristics of concrete in tension and compression, and reduce the limitation and lacuna of the traditional damage constitutive models for concrete. Furthermore, numerical test for concrete stress-strain relation under uniaxial tension and compression is given. Moreover, the damage process of concrete gravity dam is calculated and analyzed in seismic load. Compared with other damage constitutive models, the proposed model contains only one unknown parameter and the other parameters can be found in the Hsieh-Ting-Chen four-parameter yield function. The same damage evolution law, which is used for tension and compression, is good for determining stress-strain constitutive and damage characteristics in complex stress state. This coupled damage constitutive models can be applied in analyzing damage of concrete gravity dam and arch dam. 相似文献
13.
以蒙皮材料Uretek3216L为对象开展了膜材的双轴循环拉伸力学性能试验研究.首先,通过一系列双轴循环试验获得了膜材的应力应变数据,并对其非线性、各向异性等性质进行了探讨分析.然后,运用应变残差最小二乘法,计算出不同应力比组合的弹性常数.最后,分析了应力比的组合方法及正交互补性质对膜材弹性常数的影响规律.结果表明,经纬向纱线卷曲形态的不均衡性是膜材正交异性特征的主要原因.膜材的弹性常数受应力比组合方法及正交互补性质的影响显著,且弹性模量随名义应力比的改变而有规律地变化.在结构设计中,需要根据具体受力状态及应力比范围来确定膜材的弹性常数,以提高设计分析的精确性;且考虑到弹性常数的多变性,采用2组界限弹性常数比仅采用1组更可取. 相似文献
14.
WANG Yan-lei HAO Qing-duo OU Jin-ping 《重庆大学学报(英文版)》2007,6(3):221-226
In-plane shear properties of composite material laminates are very important in structural design of composite material. Four commonly used in-plane shear test methods were introduced in this paper. In order to study the differences of various shear test methods, two ASTM standard in-plane shear test methods for composite material laminates were experimentally investigated. They are ±45° tensile shear test (ASTM D3518) and V-notched rail shear test (ASTM D7078). Five types of composite material laminates composed of E-glass fiber fabric and vinyl ester resin were utilized, whose stacking sequences are 03s, 0/903s, CSM/0/902s, ±453s and (0/90)2/(±45)2/(0/90)2s, respectively. The test results indicate that the ±45° tensile shear test can predict shear moduli of composite material laminates accurately. However, the predictions of shear strength using ±45° tensile shear test are significantly lower than those of V-notched rail shear test. 相似文献
15.
Rate-dependent constitutive model of poly（ethylene terephthalate） for dynamic analysis 总被引：1，自引：0，他引：1
Uniaxial tensile testing at strain rates ranging from 10-3 to 10-1 s-1 was carried out to study the rate-dependent me-chanical behavior for poly（ethylene terephthalate） （PET） used in the packaging industry. The experimental results show that a rate-dependent plastic behavior exists for PET material. The value of the yield strength was found to increase with the increasing strain rate. A new constitutive model based on the improved Cowper-Symonds rate-dependent constitutive model is proposed to describe the mechanical behavior of PET material in the strain rate ranging from 10-3 to 10-1 s-1, providing more accurate material data for the subsequent simulation analysis of drop test and dynamic buckling. The predictions obtained using the proposed model are compared with experimental results of the improved Cowper-Symonds model. The simulating results of the proposed model agree well with the experimental data. For a low strain rate, the predictions of this model are more precise than those obtained using the improved Cowper-Symonds model. This confirms that the new constitutive model is suitable for describing the me-chanical behavior of PET material at a low strain rate and modeling impact problem. 相似文献
16.
Yttria-stabilized tetragonal-zirconia polycrystals (Y-TZP) have been shown to have superplastic properties at high temperatures, opening a way for the manufacture of complex pieces for industrial applications by a variety of techniques. However, before that is possible, it is important to analyze the deformation and fracture mechanisms at a macroscopic level based on continuum theory. In this paper, an elastic-plastic material model with a theoretical large deformation is constructed to simulate the true stress-true strain relationships of superplastic ceramics. The simplified constitutive law used for the numerical simulations is based on piecewise linear connections at the turning points of different deformation stages on the experimental stress-strain curves. The finite element model (FEM) is applied to selected tensile tests on 3-mol%-Y-TZP (3Y-TZP) co-doped with germanium oxide and other oxides (titanium, magnesium, and calcium) to verify its applicability. The results show that the stress-strain characteristics and the final deformed shapes in the finite element analysis (FEA) agree well with the tensile test experiments. It can be seen that the FEM presented can simulate the mechanical behavior of superplastic co-doped 3Y-TZP ceramics and that it offers a selective numerical simulation method for advanced development of superplastic ceramics. 相似文献
17.
运用G1eeb1e1500D热模拟试验机对柱状硼铜（USIBOR1500P）进行热拉伸试验,研究高温下热成形硼钢的变形抗力。首先将试件加热到奥氏体化温度,再以40℃／s冷却速率降到950～550℃,分别以应变速率为0．01、0．1、1／s进行热拉伸试验,获得应力一应变曲线。通过实验结果,分析成形温度、变形程度和应变速率对高温成形件的影响,并利用最小二乘法进行多元线性回归,建立高温下的本构模型。试验结果表明：成形温度和应变速率对变形抗力的影响较为敏感,变形抗力随着成形温度的升高而减小,变形抗力随着变形程度、应变速率的增加而增大。 相似文献
18.
Constitutive model of saturated soft clay with cyclic loads under unconsolidated undrained condition
An equivalent visco-elastic model of saturated soft clay was studied under unconsolidated undrained (UU) condition, which can be used to evaluate the stability of ocean foundation. Cyclic triaxial compression and extension tests were conducted to study the parameters of the model. Results showed that the relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain were nearly unique, when the initial octahedral shear stress ratios of specimens were equal to 0.3, 0.5 and 0.7. The relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain determined from the cyclic triaxial compression tests were basically the same as those determined from the cyclic triaxial extension tests. Furthermore, the relationships were not related to the initial stress condition, the test stress state and the octahedral cyclic shear stress ratio. The relationships determined from the cyclic triaxial tests under no deviatoric stress were basically the same as those determined from the cyclic triaxial tests under deviatoric stress. The change of the octahedral cyclic accumulative strain with the number of cycles was unique under different tests stress states. An equivalent visco-elastic constitutive model of saturated soft clay under UU condition was initially established. 相似文献
19.
邱贤德 《重庆大学学报(英文版)》2003,2(1)
1. Introduction In order to study rock damage and fragmentation during blasting, many numerical models have been developed. These efforts have varied from semi-empirical [1,2] to formulations based on shock wave physics [3,4]. Numerical modeling of blasting has been focusing on the complexity of the blasting process. This complexity requires that numerical models be developed in a highly systematic fashion in close coordination with controlled field and laboratory experimentation. This work d… 相似文献