Contents
1. Introduction 1
2. Mechanical integrity of welded joints and methods in characterising material constitutive parameters
3 2.1. Spot Welding Process
3 2.2. Effects of Welding parameters on Weld quality
3 2.3. Typical applications and materials system in resistance
Spot welding. 4
2.4. Microstructure and phase transformations during welding 4
2.5. Mechanical integrity of welded joints 5
2.6. The Materials behaviour of metallic materials and the properties of different welded zones
6 2.7. Mixed experimental and numerical methods in
characterising material constitutive parameters 12
3. Inverse Materials properties prediction base on the Vickers and spherical indentations.
20 3.1. Introduction and structure of the research work
20 3.2. FE modelling of the Vickers indentation and
effects of material properties 22
3.3. FE modelling of the Spherical indentation and Effects of material properties
23 3.4. Method to predict material properties from
the Vickers and Spherical indentation 24
3.4.1. Curvature of the Indentation curve 24
3.4.2. 3-D Mapping approach 25
3.4.3. Dimensional analysis and results 26
3.4.4. Chart based Intersection approach and results 28
4. Mechanical testing and FE Modelling of spot welded Joint 45
4.1.Tensile test of the base material and spot welded joint 45
4.2. Drop mass impact test and results 46
4.3. FE modelling of the spot welded joint Preliminary results 47
References
57 Contents
1.
Introduction
This report is concerned with a analysis on the development of an inversereverse modelling approach to characterise the plastic parameters of elasto plastic materials based
on the indentation method and use the approach to measure the properties of resistance spot welded joints with different material systems. Main objective is：
• To develop an reversereverse program to predict the materials properties of elasto
plastic materials based on the indentation loading curves and conventional static hardness measurements;
• To inversely measure the material properties of the nugget, HAZ and base metal
zones using indentation methods; •
To develop numerical models with realistic dimensional data, material properties and correlate the modelling results with experimental test results of static and dynamic
deformation; •
To establish the effects of welding parameters on the microstructure e.g. the dimension of the nugget and heat affected zone HAZ and strength of spot-welded
joints of mild steel and stainless steels dissimilar materials.
Progress to date of both experimental and numerical work is reported, which has met the first three main objectives of the project. F
E models of sharp indenter Vickers and blunt indenter Spherical indenter were developed. The effect of some key modelling parameters such as
mesh sensitivity, sample size and boundary conditions were assessed. Three reverseinverse modelling methods designated as dimensional analysis, 3D mapping and
dual indenter chart approach have been proposed and the validity and accuracy of each approach in predicting the material properties were systematically evaluated using
numerical indentation curves. In the experimental part, tensile shear tests have been perform on spot welded joints of different materials. A new drop weight impact testing
method has been developed and a detailed analysis approach has been established and validated, before used to analyse the performance of spot welded joints of dissimilar
materials.
2. Mechanical Integrity of Welded Joints and
