Elastic-plastic behavior of thermoplastic composites under cyclic loadings

Thesis/Dissertation · Mon Dec 31 23:00:00 EST 1990

OSTI ID:5525679

Rui, Yuting

The experimental results reveal that AS4/PEEK thermoplastic composite exhibits cyclic softening and loading range effect under symmetric cycles of strain or stress, and shows ratchetting effect under unsymmetric cycles of strain. The cyclic softening, loading range effect, ratchetting, 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. A one-parameter yield surface is used. A one-parameter memory surface is introduced to characterize the loading range effect and to distinguish the deformation process during subsequent loading from the deformation process during initial loading and overloading. Cyclic softening is achieved by the evolution of generalized plastic modulus. The ratchetting 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.

• Research Organization: Purdue Univ., Lafayette, IN (United States)
• OSTI ID: 5525679
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ANISOTROPY
COMPARATIVE EVALUATIONS
COMPOSITE MATERIALS
DEFORMATION
ELASTICITY
EVALUATION
FINITE ELEMENT METHOD
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICITY
PLASTICS
POLYMERS
RELAXATION
SIMULATION
STRESS RELAXATION
STRESSES
SYNTHETIC MATERIALS
TENSILE PROPERTIES
THERMAL STRESSES
THERMOPLASTICS