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Study on Cryomechanics of Woven Glass-Epoxy Laminates

玻璃纤维环氧层压板的低温力学研究

基本信息

批准号：
06650082
负责人：
SHINDO Yasuhide
金额：
$ 1.34万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650082/
关键词：
Fracture Mechanics Cryomechanics Woven Glass-Epoxy Laminates Numerical Simulation Fracture Toughness Tests Interlaminar Shear Strength Temperature Rise Superconducting Magnets for Magnetic Fusion Reactors 数値シミュレーション応力拡大係数熱衝撃破壊破壊靭性

项目摘要

Woven glass-epoxy laminates are used in superconducting magnets for magnetic fusion reactors and as barriers for containment of cryogenic liquids. These materials provide thermal and electrical insulation and can be subjected to large mechanical and thermal loads. Understanding variations in mechanical properties will provide useful information to the superconducting magnet designer. Because energy dissipated during crack formation or fracture of materials can affect the stability of the high performance superconducting magnets, quantification of such dissipative energy is important for superconducting magnet technology in partcular and for the understanding of mechanical behavior of materials at low temperatures in general.In this research project, the cryomechanics of woven glass-epoxy laminates is investigated.1. We consider the thermal-mechanical stress problem of cracked G-10CR glass-epoxy laminates with temperature dependent properties. The layred composite is made of one cracked … More layr bonded between two other layrs of different physical properties, and it is suddenly cooled at the surfaces. Numerical results on the transient stress intensity factor are obtained and are shown graphically.2. We examine the singular stresses of G-10CR glass-epoxy laminates with a broken layr under tension at low temperatures. Numerical results on the stress intensity factor and the order of stress singularity at different temperatures are obtained.3. We study the edge and interlaminar stress states of G-10CR woven glass-epoxy laminates with temperature dependent properties under uniform axial extension. A finite element method was used to study the influence of weave geometry and cryogenic temperatures on the edge and interlaminar stresses of two-layr woven laminates. Finite element results demonstrated that the weave geometry reduces edge stresses.4. We discuss the thermomechanical response of cracked G-10CR woven glass-epoxy laminates with temperature dependent properties. A finite element method was used to study the influence of residual thermal stresses and warp angles on the mechanical behavior of a two-layr woven laminate with a fill crack at low temperatures. Numerical calculations were carried out, and the mechanical properties and stress distributions at low temperatures are shown graphically for various warp angles. We also consider the transient thermal-mechanical stress problem of cracked G-10CR with temperature dependent properties.5. We discuss the low temperature fracture behavior of G-10 woven glass-epoxy laminates. Plane-strain fracture toughness (K_<IC>) tests were carried out with compact tension specimens at room temperature. 77K and 4K to evaluate the fracture toughness and temperature rise of woven glass-epoxy laminates. The influence of the crack length and loading rate on the low temperature fracture behavior is shown graphically. The temperature rise near the crack tip correlated with the amount of crack extension and loading rate. SEM micrograph shows the complicated structure of the damage zone near the crack tip (broken and delamination fibers, fiber pull-out, broken epoxy resin). We also study the nonlinear fracture behavior of G-10. Elastic-plastic fracture toughness (J_<IC>) tests were performed at 77K.The effect of individual damage events on the determination of J-integral resistance curves and J_Q values is discussed.6. We discuss the low temperature interlaminar shear behavior of G-10CR.Interlaminar shear tests were carried out with guillotine shear specimens at room temperature and 77K to evaluate the interlaminar shear strength (ILSS) of G-10CR glass-epoxy laminates. A three-dimensional finite element analysis was also used to interpret the experimental measurements. The effect of temperatures, notch separation and specimen thickness on interlaminar shear strength is shown graphically. Less

编织玻璃环氧树脂层压板用于磁聚变反应堆的超导磁体以及作为低温液体密封屏障。这些材料提供热绝缘和电绝缘，并且可以承受较大的机械负载和热负载。了解机械性能的变化将为超导磁体设计者提供有用的信息。由于材料在裂纹形成或断裂过程中耗散的能量会影响高性能超导磁体的稳定性，因此这种耗散能的量化对于超导磁体技术尤其重要，并且对于了解材料在低温下的机械行为具有重要意义。在本研究项目中，研究了编织玻璃-环氧树脂层压板的低温力学。 1．我们考虑具有温度依赖性特性的破裂 G-10CR 玻璃环氧树脂层压板的热机械应力问题。这种层状复合材料由一层裂纹层粘合在另外两层物理性能不同的层之间制成，并在表面突然冷却。获得了瞬态应力强度因子的数值结果并以图形方式显示。 2．我们研究了具有断裂层的 G-10CR 玻璃环氧树脂层压板在低温张力下的奇异应力。得到了不同温度下应力强度因子和应力奇点阶数的数值结果。 3．我们研究了 G-10CR 编织玻璃环氧树脂层压板的边缘和层间应力状态，该层压板在均匀轴向延伸下具有温度依赖性。采用有限元方法研究了编织几何形状和低温对两层编织层压板边缘和层间应力的影响。有限元结果表明，编织几何形状降低了边缘应力。4．我们讨论了具有温度依赖性特性的裂纹 G-10CR 玻璃纤维环氧层压板的热机械响应。采用有限元方法研究了残余热应力和翘曲角对带填充裂纹的两层编织层压板低温力学行为的影响。进行了数值计算，并以图形方式显示了不同翘曲角度下的低温机械性能和应力分布。我们还考虑了具有温度依赖性特性的裂纹G-10CR的瞬态热机械应力问题。5．我们讨论了 G-10 玻璃纤维环氧层压板的低温断裂行为。在室温下用致密拉伸试样进行平面应变断裂韧性（K_<IC>）测试。 77K 和 4K 用于评估玻璃纤维环氧层压板的断裂韧性和温升。以图形方式显示了裂纹长度和加载速率对低温断裂行为的影响。裂纹尖端附近的温升与裂纹扩展量和加载速率相关。 SEM 显微照片显示裂纹尖端附近损伤区的复杂结构（纤维断裂和分层、纤维拔出、环氧树脂断裂）。我们还研究了 G-10 的非线性断裂行为。在77K下进行弹塑性断裂韧性(J_<IC>)试验。讨论了单个损伤事件对J-积分阻力曲线和J_Q值确定的影响。 6．我们讨论了G-10CR的低温层间剪切行为。在室温和77K下用闸刀剪切试样进行层间剪切试验，以评估G-10CR玻璃环氧层压板的层间剪切强度（ILSS）。三维有限元分析也用于解释实验测量结果。以图形方式显示了温度、缺口间距和样品厚度对层间剪切强度的影响。较少的