对粘弹性聚合物材料的耐用性进行数值模拟,这些材料受到可变负载的疲劳,基于热损伤标准
Yutong Li1, M J Mohammad Fikry2, Jun Koyanagi1
1Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
Polymers
|October 26, 2024
概括
负载历史显著影响碳纤维增强塑料 (CFRPs) 的故障. 频繁的负载变化和暂停加速损坏,导致过早失效和比Palmgren-Miner规则预测的更短的疲劳寿命.
科学领域:
- 材料科学 材料科学 材料科学
- 机械工程 机械工程
- 聚合物科学 聚合物科学
背景情况:
- 碳纤维增强塑料 (CFRP) 容易因其粘弹性聚合物基质而过早失效.
- 了解复杂负载历史的影响对于CFRP中精确的疲劳寿命预测至关重要.
- 像Palmgren-Miner规则这样的现有方法可能无法充分捕捉在变量负载下损坏的积累.
研究的目的:
- 调查负载历史,包括振幅变化和中断,对CFRP过早失效的影响.
- 在复杂的负载条件下应用断裂疲劳缩 (FFE) 损伤标准来预测疲劳寿命.
- 将模拟结果与来自Palmgren-Miner规则的预测进行比较.
主要方法:
- 在ABAQUS软件中使用用户定义的子程序 (UMAT) 来实现FFE损坏标准.
- 在各种可变幅度负载模式下的模拟疲劳寿命,包括频繁的变化和间歇性暂停.
- 基于传统的线性损坏积累方法 (帕姆格伦-米纳规则) 设计的负载场景.
主要成果:
- 发现频繁的负载幅度变化和短暂的负载中断加速了聚合物矩阵损伤的积累.
- 模拟疲劳寿命差异很大,从帕姆格伦-米纳规则预测的33.6%到91.9%不等.
- 确定了预测疲劳寿命远远低于实际结果的场景.
结论:
- FFE标准提供了一种更实用和可靠的方法,用于预测CFRP在复杂负载下疲劳寿命.
- 负载历史,包括振幅波动和暂停,极大地影响过早失效.
- 这项研究突出了Palmgren-Miner规则对于复杂的可变广度疲劳分析的局限性.
相关概念视频
01:21Fatigue
174
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
174
01:21Plastic Behavior
189
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and...
189
01:20Strain-Energy Density
370
Understanding the strain energy density in materials under axial load is crucial for evaluating their mechanical behavior and durability. When a rod is subjected to such a load, it elongates and stores energy, known as strain energy, as potential energy within the material. This energy is measured in terms of energy per unit volume.
In the elastic region of a material, the relationship between the stress and the strain is linear and follows Hooke's Law. The strain energy density in this...
In the elastic region of a material, the relationship between the stress and the strain is linear and follows Hooke's Law. The strain energy density in this...
370
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
251
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
251
01:22Generalized Hooke's Law
844
The generalized Hooke's Law is a broadened version of Hooke's Law, which extends to all types of stress and in every direction. Consider an isotropic material shaped into a cube subjected to multiaxial loading. In this scenario, normal stresses are exerted along the three coordinate axes. As a result of these stresses, the cubic shape deforms into a rectangular parallelepiped. Despite this deformation, the new shape maintains equal sides, and there is a normal strain in the direction of the...
844
01:26Hooke's Law
350
Hooke's law, a pivotal principle in material science, establishes that the strain a material undergoes is directly proportional to the applied stress, defined by a factor called the modulus of elasticity or Young's modulus.
350