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991.
AbstractIn this paper, the effects of hygrothermal conditions on various behaviors, such as bending, free vibration, mechanical and thermal buckling, of exponentially graded microplates lying on two-parameter elastic foundations are investigated. The trigonometric four-variable plate theory incorporated to the modified couple stress theory (MCST) is employed to derive the equations of motion. The present MCST contains an internal material length scale parameter, thus it can capture the size effect. The microplate is assumed to be subjected to a temperature rise and moisture concentration which are varied linearly through the thickness of the plate. Based on an exponential law, the material properties of the microplate are graded only in z direction. The equations of motion are solved analytically to obtain the displacements, stresses, eigenfrequencies and critical buckling load and temperature of the microplates. The present results are validated by comparing them with those previously published. The numerical examples reveal that considering the size effect and/or the elastic foundations leads to an increment in plate stiffness and thereby leads to a decrement in the deflection and an increment in eigenfrequency and buckling loads. It is also shown that the size effect is negligible for the thicker plate. 相似文献
992.
993.
以FeSiB非晶带材为熔覆材料,采用激光熔覆在低碳钢表面制备高致密度涂层,利用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度仪等研究不同脉冲宽度对激光熔覆涂层成形、组织特征及硬度的影响。结果表明:随脉冲宽度增大,涂层稀释率升高;裂纹倾向增加,裂纹源萌生由表面到界面处;晶化程度升高,结晶相为α-Fe,Fe_2B和Fe_3Si;熔合区宽度增大,柱状晶沿外延生长趋势更大;显微硬度先增加后减小。当脉冲宽度为3.2ms时,涂层结构致密,无孔洞缺陷,界面呈良好的冶金结合,稀释率低,为23.2%,涂层平均显微硬度达1192HV,约为基材的10倍。 相似文献
994.
995.
纳米钛酸锶的制备及超声降解碱性品红废水研究 总被引:1,自引:0,他引:1
以硝酸锶、钛酸四丁酯、柠檬酸和乙二醇为原料,采用络合溶胶-凝胶法制备钛酸锶纳米粉体,借助粉末X射线衍射仪(XRD)、扫描电子显微镜(SEM)对产物进行表征。对产品降解碱性品红的性能进行研究,对比试验了无钛酸锶、不同钛酸锶添加量、不同双氧水加量对一定浓度碱性品红降解率的影响。结果表明:碱性品红浓度为40mg/L,钛酸锶用量为1g/L,双氧水为5mL/L时,超声降解10min,碱性品红降解率达97.7%,且回收7次重复使用降解效果仍在95%以上。这种方法对处理三苯甲烷类染料废水有一定实用参考意义。 相似文献
996.
In this paper, a non-collinear shear wave mixing technique is proposed for evaluation of fatigue crack orientation. Numerical analysis of the nonlinear interaction of two shear waves with crack is performed using two-dimensional finite-element simulations. The simulation results show that the nonlinear interaction of the two shears waves with cracks leads to the generation of transmitted and reflected sum-frequency longitudinal waves (SFLW), moreover the propagation direction of reflected SFLW is correlated with the orientation of crack, which can be used for crack orientation evaluation. Non-collinear wave-mixing experiments were conducted on specimens with fatigue crack. The experimental results show that the directivity of the generated SFLW agrees well with the simulation results, and non-collinear shear wave mixing has potential use in fatigue crack orientation evaluation. 相似文献
997.
998.
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1000.
Tomoyuki Fujii Keiichiro Tohgo Masafumi Fujioka Muhamad Safwan Bin Muhamad Azmi Kodai Kikushima Yoshinobu Shimamura 《Fatigue & Fracture of Engineering Materials & Structures》2020,43(9):1917-1927
This paper proposes an alternating bending technique for evaluating fatigue life in the low‐to‐high cycle fatigue regime. A method was developed for estimating the stress, elastic strain, and plastic strain ranges of a plastically deformed specimen subjected to alternating bending with consideration of stress and strain distributions. To evaluate its effectiveness, fatigue testing was conducted using a specimen made of a steel used for pressure vessels. The stress, elastic strain, and plastic strain ranges could be obtained during cyclic bending. The elastic strain amplitude life and plastic strain amplitude life curves were linear in a log–log plot in the low‐to‐high cycle fatigue regime. Hence, the fatigue life under alternating bending could be evaluated using the proposed strain‐based approach. However, these curves could not be predicted using equations with parameters obtained from tensile testing, such as the universal slope method, due to the strain gradient in the specimen. 相似文献