Related Experiment Video
Updated: Sep 9, 2025
07:53
Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates
Published on: April 27, 2019
8.4K
Elastoplastic Modeling of Kevlar® Composite Laminates: A Cyclic Loading Approach for In-Plane Characterization
Rene Alejandro Canceco de la Cruz1, Luis Adrián Zúñiga Avilés2, Gabriel Plascencia Barrera1
1Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Av. Miguel de Cervantes #120, Complejo Industrial Chihuahua, Chihuahua 31136, Mexico.
Polymers
|August 28, 2025
Summary
This study details the elastoplastic behavior of Kevlar® fiber composites, developing a model to predict their nonlinear hardening and stiffness for impact resistance.
Area of Science:
- Materials Science
- Composite Materials
- Mechanical Engineering
Background:
- Phenol formaldehyde/polyvinyl butyral (PF/PVB) matrix composites reinforced with Kevlar® fibers are crucial for impact-resistant applications.
- Understanding their elastoplastic behavior under tensile loading is essential for design optimization.
Purpose of the Study:
- To investigate the in-plane elastoplastic behavior of Kevlar®/PF/PVB composites.
- To develop and validate a novel elastoplastic constitutive model for these composites.
- To provide essential mechanical properties and constitutive relationships for designing advanced composite structures.
Main Methods:
- Comprehensive in-plane tensile testing, including cyclic loading-unloading tests at a 100%/min strain rate.
- Development of an elastoplastic constitutive model using Hill's yield criterion and an isotropic hardening function.
- Testing of laminates with various stacking sequences (0°, 90°, ±45°) and assessment of model predictions.
Main Results:
- Significant nonlinear hardening and yarn stiffening effects were observed beyond yield stress.
- The developed model accurately predicted nonlinear behavior but overestimated stress-strain response in laminates experiencing delamination.
- An adapted model provided a lower bound for the stress-strain response in delaminated cases, accounting for plastic strains within plies.
Conclusions:
- The study provides valuable mechanical properties and constitutive relationships for Kevlar®/PF/PVB composites.
- The developed model offers reasonable limits for predicting the stress-strain response, particularly for plastic strains within plies.
- This research contributes to the design of tailored composite structures for enhanced impact resistance.
Related Concept Videos
01:18Residual Stresses in Bending
250
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
250
01:19Members Made of Elastoplastic Material
156
The behavior of elastoplastic materials under bending stresses, particularly in structural members with rectangular cross-sections, is crucial for predicting material responses and understanding failure modes. Initially, when a bending moment is applied, the stress distribution across the section follows Hooke's Law and is linear and elastic. This distribution means the stress increases from the neutral axis to the maximum at the outer fibers, up to the elastic limit.
As the bending moment...
As the bending moment...
156
01:21Plastic Behavior
261
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...
261
01:20Elastic Strain Energy for Shearing Stresses
277
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
277
01:24Circular Shafts - Elastoplastic Materials
159
The study of solid circular shafts under stress shows that within the elastic limit, stress increases directly to the distance from the shaft's center. This relationship holds until the shaft reaches a critical point of stress, beyond which it begins to yield, marking the transition from elastic to plastic deformation. At this crucial juncture, the maximum torque the shaft can endure without permanent deformation is determined, signifying the limit of its elastic behavior.
As torque on the...
As torque on the...
159
01:20Normal Strain under Axial Loading
656
Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio...
656