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Damage behaviour and GTN parameter analysis of TC4 powder metallurgy titanium alloy during hot deformation

Liu Ronge, Wang Baoyu, Hu Shushan

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 3

art. no. e165, 2023

The damage and fracture behaviour of TC4 powder metallurgy titanium alloy were studied by isothermal uniaxial tensile tests. The results show that microcracks formed at grain boundaries, inclusions, initial pores, and adjacent pores and cracks were gathered and perpendicularly linked to the tensile direction, eventually leading to the macroscopic fracture of the material. Increasing the temperature and strain rate promotes the occurrence of dynamic recovery and subgrain merging nucleation, which leads to an increase in the fracture strain and plasticity of the material. Combined with the response surface methodology and genetic optimization algorithm, the GTN damage parameters were obtained by the reverse calibration method. The calculated flow stresses, based on the GTN damage model, are in good agreement with the experimental ones, indicating that the damage parameters can reflect the damage process of the material. In this study, the sensitivity of the damage parameters along with the influence of temperature and strain rate on them was analysed.

Elastomeric matrix composites: effect of processing conditions on the physical, mechanical and viscoelastic properties

Zaimova D, Bayraktar E., Katundi D., Dishovsky N

Journal of Achievements in Materials and Manufacturing Engineering

2012

Vol. 50, nr 2

81--91

Purpose: The aim of this study is to investigate the influence of accelerator-vulcanizing agent system and the vulcanization temperature on the properties of vulcanizates based on Natural rubber/Polybutadiene rubber (NR/ BR) compounds. This preliminary study will allow optimizing the composition for improving the mechanical properties and understanding the damage behaviour. Design/methodology/approach: NR/BR based composites with different vulcanization temperatures and curing systems were characterized in respect of their curing characteristics (for 140°C and 160°C) and mechanical properties. The cure characteristics of the rubber compounds were studied by using the Monsanto MDR 2000 rheometer. The mechanical properties were investigated- tensile strength, elongation at break, tensile modulus at 100% (M100) and at 300% (M300) deformation. The hardness (Shore A) and molecular mass of the samples were also determined. Scanning electron microscopy was used to study the microstructure of the fracture surfaces. Findings: The processing, physical, mechanical and viscoelastic properties and chemical structure of the mixture of Natural rubber/Polybutadiene rubber (NR/BR) compounds have been evaluated in detail for the compounds of D1 and D2 (140/160). Research limitations/implications limitations/implications: Some critical point, control of the temperature during vulcanization in press, can introduce some restrictions; these measurements can play on the final vulcanizates and in the course of processing. Practical implications: In practical way, mechanical test results (tensile and shore A) give very useful information about the damage behaviour of the elastomeric matrix composites. Originality/valut: Natural rubber/Polybutadiene rubber (NR/BR) compounds were mixed by additions of some certain elements to improve physical, mechanical and viscoelastic properties and damage behaviours of these compounds produced under certain conditions.