Microstructural behavior of magnetorheological elastomer undergoing durability evaluation by stress relaxation
Mohd Aidy Faizal Johari1, Saiful Amri Mazlan2, Mohamed Mahmoud Nasef3
1Engineering Materials and Structures (eMast) ikhoza, Malaysia-Japan, International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, 54100, Kuala Lumpur, Malaysia.
Scientific Reports
|May 26, 2021
Summary
This study investigated magnetorheological elastomer (MRE) durability under stress relaxation. Researchers observed significant performance degradation linked to microstructural changes like molecular slippage and shear bands over an extended test duration.
Area of Science:
- Materials Science
- Polymer Science
- Mechanical Engineering
Background:
- Magnetorheological elastomers (MREs) are widely used, but their microstructural durability under stress is not well understood.
- Existing research lacks comprehensive experimental and theoretical data on MRE microstructural behavior, limiting their application.
- Understanding MRE microstructural durability is crucial for optimizing their performance and lifespan in various applications.
Purpose of the Study:
- To investigate the microstructural durability of magnetorheological elastomers (MREs) under prolonged stress relaxation.
- To identify and analyze the micro-mechanisms responsible for performance degradation in MREs during stress relaxation.
- To correlate observed microstructural phenomena with changes in viscoelastic properties.
Main Methods:
- Preparation of MRE samples using silicon rubber (SR) and 70 wt% carbonyl iron particles (CIP).
- Stress relaxation evaluation under torsional shear load with constant low strain (0.01%) within the linear viscoelastic (LVE) region.
- Microstructural analysis using Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) in in-phase mode.
Main Results:
- MRE samples exhibited significant performance degradation over an 84,000-second test duration, the longest reported for MRE stress relaxation studies.
- Storage modulus decreased by 8.7%, normal force weakened by 27%, and stress performance reduced by 6.88%.
- Novel micro-mechanisms including molecular slippage, disentanglement, microplasticity, microphase separation, and shear band formation were identified as causes of performance depletion.
Conclusions:
- The study established a systematic correlation between microstructural deformation and the durability performance of MRE under stress relaxation.
- Identified microstructural phenomena provide insights into the viscoelastic property changes and degradation mechanisms in MREs.
- The findings contribute to a better understanding of MRE behavior, crucial for advancing their application in demanding environments.
More Related Videos
Related Concept Videos
01:21Plastic Behavior
341
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...
341
01:18Residual Stresses in Bending
363
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...
363
01:19Members Made of Elastoplastic Material
229
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...
229
01:24Stress-Strain Diagram - Ductile Materials
1.2K
The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...
1.2K
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
385
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.
385
01:10Residual Stresses in Circular Shafts
328
In materials that exhibit elastic and plastic behavior, known as elastoplastic materials, residual stresses can accumulate when these materials experience plastic deformation. This deformation arises from either high levels of shearing stress or significant strains. Residual stresses are internal stresses that persist within a material after removing the external force causing deformation. This phenomenon is demonstrated when observing the behavior of a shaft under torque; notably, the...
328