水分影响下聚氨酯胶粘剂断裂行为的数值研究
Numerical investigation of fracture behaviour of polyurethane adhesives under the influence of moisture
AI总结：
本文通过将有限应变粘弹性模型与相场损伤模型耦合，数值研究了水分对聚氨酯胶粘剂断裂行为的影响，并利用不同湿度老化试样的撕裂强度实验数据识别了相场损伤参数。
摘要：
聚氨酯胶粘剂广泛用于轻量化部件的制造。这类胶粘剂具有吸湿性，在环境条件下老化会导致其力学性能退化。由于粘弹性特性，聚氨酯胶粘剂表现出非线性的率相关行为，并近似呈现不可压缩变形。基于连续流变模型，通过将弹簧和Maxwell单元并联，建立了有限应变粘弹性模型。通过将力学自由能分解为体积部分和等容部分来考虑近似不可压缩特性。本工作重点研究水分对断裂行为的影响。相场损伤模型已被证明是研究断裂行为的有效方法。因此，将有限应变粘弹性材料模型与相场模型耦合，以研究断裂行为。假设材料为各向同性，因此考虑总力学能用于体相退化。对不同湿度条件下老化的试样进行实验，以了解撕裂强度。这些测试结果用于通过数值研究识别相场损伤材料参数。
英文摘要：
Polyurethane adhesives are extensively used in manufacturing of the lightweight components. These adhesives are hygroscopic in nature causing the material to degrade their mechanical properties due to ageing under environmental conditions. Polyurethane adhesive shows non-linear rate-dependent behaviour due to viscoelastic properties and assumes nearly incompressible deformation. Finite-strain viscoelastic model is formulated based on the continuum rheological model by combining spring and Maxwell elements in parallel. Nearly incompressible property is considered by decomposing the mechanical free energy into volumetric and isochoric parts. This work focuses on the investigation of the influence of moisture on the fracture behaviour. Phase-field damage model proved to be an efficient method to investigate the fracture behaviour. Therefore, the finite-strain viscoelastic material model is coupled with the phase-field model to investigate fracture behaviour. Material is assumed to be isotropic, therefore the total mechanical energy is considered for bulk degradation. Experiments are conducted on the samples aged for different humid conditions to understand tear strength. These test results are used to identify the phase-field damage material parameters from numerical investigation.
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