Mechanical properties of ductile materials (experiment and finite element analysis)

Abstract

Tensile test is one of the ways to study how strong a material. By leaving the damaged procedure, tensile test tend to be more accurate to compare it to other similar hardness test. The most of important in mechanical testing is techniques of strain measurement. A several of technique exists for measuring strain in the tensile test such as by machine crosshead motion and extensometer. These technique has its own advantages and disadvantages. Apart from the experiment using Universal Testing Machine, the Finite Element Analysis method (simulation) was also used to study the mechanical properties of mild steel. Demand for the measurement accuracy and the different in changes in elongation for this mechanical properties testing will be investigated. This comparison base on the mechanical properties of material according modulus of elasticity, ultimate tensile strength, yield strength and percentage of elongation. In this experiment, the average of Elastic’s modulus is 24.47GPa, Yield’s strength is 306.67MPa, and elongation is 22.33mm. The machine crosshead motion showed high variability in the strain measurement. The Elastic’s modulus values were not in acceptable range. Therefore, the machine crosshead technique is not used for modulus measurement techniques. From the stress-strain graph it is understood that the mild steel follows the Hooke’s Law (elastic linear line). For the example, stress is directly proportional to strain. After the linear region in the graph, there occurs necking on the specimen and finally it breaks. In finite element analysis’s result, parabolic type is more appropriate for data. Percentage of estimated global error for parabolic is lower than linear, which is 5.163% and 9.016% respectively. The comparison between experiment and simulation is slightly different of the results. This is because affected by several factors such as temperature, crosshead motion, placement the specimen at gripper (Universal Testing Machine), and the composition of the mild steel. Therefore, even if the same ty e of material and the same size that can result will be different.