Related Experiment Video
Updated: Jun 14, 2025
08:21
Quantitative Hardness Measurement by Instrumented AFM-indentation
Published on: November 22, 2016
9.6K
Inverse Method to Determine Parameters for Time-Dependent and Cyclic Plastic Material Behavior from Instrumented
Hafiz Muhammad Sajjad1, Thomas Chudoba2, Alexander Hartmaier1
1Interdisciplinary Centre for Advanced Material Simulation (ICAMS), Ruhr-Universität Bochum, Universitätsstr 150, 44801 Bochum, Germany.
Materials (Basel, Switzerland)
|August 29, 2024
Summary
This study introduces an inverse analysis method combining instrumented indentation tests and simulations to determine time-dependent material properties. The approach successfully characterized viscoplastic behavior and work-hardening in martensitic steel.
Area of Science:
- Materials Science
- Mechanical Engineering
- Computational Mechanics
Background:
- Instrumented indentation testing is a key method for evaluating material hardness and elastic properties.
- Advanced techniques combine indentation with simulations to determine complex material characteristics like yield strength and work-hardening.
- Inverse analysis offers a powerful approach to extract material parameters by minimizing discrepancies between simulated and experimental indentation data.
Purpose of the Study:
- To develop a protocol for instrumented indentation tests and an inverse analysis procedure.
- To obtain material parameters for time-dependent viscoplastic behavior and kinematic/isotropic work-hardening.
- To compare two optimization strategies for parameter identification.
Main Methods:
- Developed a protocol for instrumented indentation tests.
- Implemented an inverse analysis procedure to determine material parameters from experimental data.
- Assumed known elastic properties and initial yield strength, which are independently determinable.
- Employed and compared two distinct optimization strategies for parameter identification.
Main Results:
- Successfully obtained material parameters for time-dependent viscoplastic behavior.
- Characterized kinematic and isotropic work-hardening using the developed inverse method.
- Applied the new inverse method for spherical indentation to martensitic steel, demonstrating its efficacy.
Conclusions:
- The developed inverse analysis method effectively determines time-dependent viscoplastic material parameters and work-hardening characteristics.
- The protocol is successfully validated through application to martensitic steel.
- This approach enhances the capability of indentation testing for comprehensive material characterization.
Related Concept Videos
01:21Plastic Behavior
192
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...
192
01:19Plastic Deformations
123
Plastic deformation represents a fundamental concept in materials science, which explains the irreversible change in the shape of a material when it experiences stress beyond its elastic capability. This phenomenon is important in structural engineering, especially in designing and analyzing cantilever beams—structures that are securely fixed at one end and bear loads at the opposite end. When these beams are subjected to loads within their elastic range, they will return to their...
123
01:19Members Made of Elastoplastic Material
94
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...
94
01:20Plastic Deformation in Circular Shafts
182
When materials are subjected to forces that surpass their yield strength, they undergo a process known as plastic deformation. This results in a permanent alteration or strain in their structure. This concept can be specifically applied to circular shafts, where the deformation leads to a change in its shape. The precise evaluation of this plastic deformation requires understanding the stress distribution within the circular shaft, which is achieved by calculating the maximum shearing stress in...
182
01:18Residual Stresses in Bending
153
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...
153
01:12Temperature Dependent Deformation
143
In a nonhomogeneous rod made up of steel and brass, restrained at both ends and subjected to a temperature change, several steps are involved in calculating the stress and compressive load. Due to the problem's static indeterminacy, one end support is disconnected, allowing the rod to experience the temperature change freely. Next, an unknown force is applied at the free end, triggering deformations in the rod's steel and brass portions. These deformations are then calculated and added...
143