Showing 5 results for Residual Stress
S. Ansari, E. Ranjbarnodeh, M. Iranmanesh,
Volume 2, Issue 2 (11-2016)
Abstract
Studies on welding process of Aluminium weldments shows that post-weld residual stress and deformation are influential on structure efficiency and there are different variable which affect these stresses and deformation. In this study the effect of geometrical variables and welding sequence on residual stresses and deformation in Aluminium H321 have investigated by the finite element software Ansys. Thermo elastic-plastic model was verified by metallography experiment and measurement of post-weld deformation afterward, weld leg, penetration depth and welding sequence were optimized to minimize the distortion. It was concluded that weld-volume increase post-weld distortion and it can be minimize by choosing an appropriate weld sequence
A. Kesharvarz, E. Ranjbarnodeh, M. Fadavie-Ardestani, M. Saeed Kiasat,
Volume 3, Issue 1 (8-2017)
Abstract
Nowdays, the prediction and prevention of fatigue failures is converted to one of the most concerns for industry owners. Since the processes of fatigue suddenly occur, it is most important and necessary to recognize the effective factors of fatigue life of structures. Mechanical and thermal multiple loading are the important factors of the fatigue failure. In order to appropriate fatigue design, analysis should be validated with experimental results. In present research, fatigue life of A36 welded steel samples obtained from test is compared by finite element results obtained from commercial ansys pakage. In this research, the effects of residual stress, reinforcement, notch and thickness of sampels on fatigue life are studied. Results of analytical simulation and experimental show good agreement. Results also shows the dominant effect of reinforcement on the fatigue life.
A. Parvaresh, H. Sabet, M. Roohnia,
Volume 3, Issue 2 (1-2018)
Abstract
In this research, the effect of different welding parameters on residual stress and microstructure of the weld region, as well as the comparison of two methods of measuring residual stress using critical fracture longitudinal wave method and preformation method have been investigated. For this purpose, the taguchi DOE methodology is used as a statistical method to optimize four parameters of pulse current, base current, and pulse on time% and pulse frequency to minimize longitudinal residual stresses in austenite 304 AISI stainless steel. After welding, stress measurements were performed using two methods critical fracture longitudinal and perforation, and hardness, tensile and OM tests were performed on the specimens. The tests results show that at all levels of the pulse parameters arranged with the standard L9 Taguchi array, the incident heat input is irrefutable and the effect of this parameter is move then 50%. The optimum conditions obtained while the highest frequency level should be considered. The general trend is achieved from the residual stress measurement charts is consistent with the logic of stress distribution in both methods. Sample number 1 with stress equivalent to 232 MPa and sample number 9 with stress of MPa 126 in ultrasonic method with frequency 4 MHz have the highest and lowest stress among different samples, respectively. The size of the coaxial grains weld was directly related to the incoming heat, so that the least amount of coaxial grains in the welding center was related to specimens NO. 3 and 9 with grain size of 8 µm and 9 µm, which in these samples had the lowest amount of welding heat is measured. The samples 1 and 4 with HV 128 and HV 144 hardness and MPa 633 and MPa 639 have the least hardness and tensile strength and the highest strength and hardness of sampled 3 and 9 with 166 and 161 hardness and tensile strength MPa 703 and MPa 695.
N. Habibi, H. Eskandari,
Volume 5, Issue 2 (1-2020)
Abstract
Welded tubular joints are widely used in various industry structures for high efficiency subjected to pressure, bending and twisting.Welded structures are the main parts of structures, buildings, bridges, gas pipes, pressure vessels and power transmission equipment in the ship building, construction, oil, gas, petrochemical industries and power plants.A sample of pipe-welded joints is a X-tubular joint that has been investigated in this study.The main objective of the present work is to investigate the heat transfer and residual stress caused by the three-stage welding process in X-tubular joint made of St52 using Simufact Welding software.The welding process involves three welding steps using arc welding. The finite element model contains the thermal and mechanical properties of base metal and welding metal as a function of temperature.Also, advanced modeling tools such as mesh adaptation during the process and meshing compatible with the welding site, the birth and death technique of the element and the source of heat transfer have been used.Welding simulation showed that significant residual stresses were created in the joint after welding. Comparison of the results shows that the numerical results and empirical measurements are in good agreement with each other and the existing model can provide a good prediction of temperature distribution and stress control in this welding process.
M. Sabokrouh ,
Volume 5, Issue 2 (1-2020)
Abstract
In this article the effects of carburizing heat treatment on girth weld with containing titanium oxide and titanium carbide nanoparticles (X-65 grade of gas pipeline) is evaluated. The charpy results show that in the carburized sample containing titanium oxide and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium carbide and titanium carbide nanoparticles), has been respectively increased by 6% and 42%. Also, the ultimate strength carburized sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles) has been respectively increased by 20% and 28%. The results show that the fatigue life in both carburized nano-alloy samples has been increased. The fatigue life in the carburized sample of titanium carbide nanoparticles has increased more than that of titanium oxide nanoparticles. The fatigue test results show that in the carburized sample containing titanium carbide nanoparticles compared to the tempered sample containing titanium oxide nanoparticles, fatigue life (150-N force) has been increased by 20%. In this loading the fatigue life (tempered sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by 31%. The results show that the residual stress in both carburized nano-alloy samples has been decreased The hole drilling strain gage results show that in the tempered sample containing titanium oxide oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide nanoparticles and titanium carbide nanoparticles), hoop residual stresses has been respectively decreased by 9% and 6%.
