Study of the effective parameters on welding residual stress relaxation in aluminum cylindrical shells under cyclic pressure

2019 ◽  
Vol 143 ◽  
pp. 106235
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Cylindrical Shells ◽  
Welding Residual Stress ◽  
Effective Parameters ◽  
Cyclic Pressure ◽  
Residual Stress Relaxation

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

scholarly journals Residual Stress Relaxation of DRWDs in OSDs under Constant/Variable Amplitude Cyclic Loading

2020 ◽  
Vol 11 (1) ◽  
pp. 253
Author(s):  
Wen Zhong ◽  
Youliang Ding ◽  
Yongsheng Song ◽  
Fangfang Geng ◽  
Zhiwen Wang
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Welding Residual Stress ◽  
External Loading ◽  
Analysis Model ◽  
Variable Amplitude ◽  
Residual Stress Relaxation

An orthotropic steel deck (OSD) has a complicated structure, and its fatigue life is mainly determined by various welding details. Fatigue assessment of deck-to-rib welding details (DRWDs) under long-term train loads is an important concern for engineers. Properly assessing the initial residual stress and the mechanism of stress relaxation in DRWDs under long-term external loading is a prerequisite for predicting the fatigue damage and service life of OSDs. In this paper, a finite element analysis method is proposed to calculate the residual stress relaxation in DRWDs of OSDs under constant/variable amplitude cyclic loading. First, experiments on full-size OSD specimens were carried out using the hole drilling strain-gauge method, and the multi-axial distribution characteristics of residual stress on the sub-surface of the deck were obtained. On this basis, a refined residual stress analysis model of DRWDs using thermal-structural sequence coupling analysis and life and death unit technology is established, and the accuracy of the model is verified by the test data. Second, a coupling stress analysis model that considers the welding residual stress and mechanical stress using cyclic plastic constitutive model is established. The combined influence of number of cycles, stress amplitude, and stress ratio on multi-axial residual stress relaxation effect under constant/variable amplitude cyclic loading is investigated. Finally, a release formula of welding residual stress relaxation coefficient is proposed based on the external loading stress amplitude, stress ratio, and material yield stress. The results show that (1) with the increase in the number of loading cycles, the stress decreases until it is stabilized, while the global distribution of welding residual stress remains unchanged. Most of the welding residual stress release (about 95%) occurs in the first cycle; (2) the residual stress relaxation decreases with the increase in stress amplitude and increases linearly with the stress ratio; (3) the residual stress release is controlled by the maximum amplitude stress in the variable amplitude cyclic loading. After the residual stress is released, the stress will not continue to be released if the DRWDs have the same or smaller amplitude loading.

Fatigue Life Numerical Prediction of Butt Welded Plate under Cyclic Loading

2013 ◽  
Vol 838-841 ◽  
pp. 265-269
Author(s):  
Yi Fei Wang ◽  
Wei Lian Qu ◽  
Er Nian Zhao ◽  
Bai Feng Ji ◽  
Liang Wang
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Life Prediction ◽  
Welding Residual Stress ◽  
Fatigue Life Prediction ◽  
Design Code ◽  
Welded Structures ◽  
Residual Stress Relaxation

Fatigue failure of welded structure has been highly concerned in structural engineering field. At present, the numerical simulation method has been actively applied on fatigue life prediction of welded structures. In this paper, welding residual stress of a butt welded plate was simulated by thermal elastic-plastic finite element method, and welding residual stress relaxation behavior under overload was analyzed. Then, the fatigue life of the welding plate under cyclic loading was numerically predicted with considering the welding residual stress and welding residual stress relaxation, and the result was compared with that calculated according to current steel structures design code of China. The results show that, considering fatigue reliability, the fatigue life calculated based on design formulas of the steel design code is more conservative, and numerical method for fatigue life prediction of welded structures, considering the welding residual stress and welding residual stress relaxation, is a feasible method.

scholarly journals Prediction of Residual Stress Relaxation of Shot Peened 2024-T351 Aluminum Alloy: Part 1

2011 ◽  
Vol 462-463 ◽  
pp. 1355-1360
Author(s):  
Omar Suliman Zaroog ◽  
Aidy Ali ◽  
Sahari B. Barkawi
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Shot Peening ◽  
Applied Load ◽  
Cold Work ◽  
Cyclic Tests ◽  
Initial State ◽  
Loading Cycle ◽  
Residual Stress Relaxation ◽  
Alloy Part

It is important to account for residual stress relaxation phenomenon in the design of the component. Specimens of 2024-T351 aluminium alloy were used in this study. The specimens were shot peened under three different shot peening intensities. Cyclic tests for two load magnitudes were performed for 1, 2, 10, 1000 and 10000 cycles. Residual stresses, microhardness and the cold work percentage were measured at initial state and after each loading cycle for the three shot peening intensities and for the two loads. The study revealed that most of the drop in the residual stress, microhardness and cold work happened in the first cycle are dependent on the applied load.

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