Elastic-plastic behavior of thermoplastic composites under cyclic loadings
The experimental results reveal that AS4/PEEK thermoplastic composites exhibit cyclic softening and loading range effect under symmetric cycles of strain or stress, and show ratcheting effects under unsymmetric cycles of stress and mean stress relaxation under unsymmetric cycles of strain. The cyclic softening, loading-range effect, ratcheting and mean stress relaxation are anisotropic. Based on the essential features of the material behavior, an elastic-plastic constitutive model is proposed to describe the material response under cyclic loadings. Cyclic softening is achieved by the evolution of a generalized plastic modulus. The ratcheting effect is modeled in the frame of time-independent cyclic plasticity by the change of the generalized plastic modulus. Good agreement between the model simulations and the experimental data is obtained. The proposed model is applied to form the constitutive relations of laminates with and without thermal stress by using classical lamination theory. A numerical iteration scheme is presented for the nonlinear finite-element analysis of structural laminates.
- Research Organization:
- Purdue Univ., Lafayette, IN (United States)
- OSTI ID:
- 5458442
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
COMPOSITE MATERIALS
DEFORMATION
ELASTICITY
FUNCTIONAL MODELS
MATERIALS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICITY
PLASTICS
POLYMERS
RATCHETING
RELAXATION
STRAIN SOFTENING
STRESS RELAXATION
SYNTHETIC MATERIALS
TENSILE PROPERTIES
THERMOPLASTICS