Finite Element Simulation of Shot Peening Coverage with the Special Attention on Surface Nanocrystallization

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A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses

Among different parts of a vehicle, the body is the main load-bearing component and as a result, its durability is critical. Fatigue analyses are typically divided into different categories, the quasi-static methods and the dynamic methods. The aim of this paper was to compare the inertia relief and modal dynamic approaches for their formulation, accuracy and computation time. The chosen case study is the fatigue life of the vehicle body. By utilizing multi-body dynamics model and driving the vehicle on different standardized roads and by different velocities, the force and moment time histories which act on the body were calculated and later used by the finite element model for the stress analysis. Then, by using the structural stress method, the fatigue life of the vehicle spot welds were calculated and the results were compared for both quasi-static and dynamic approaches. The findings reveal that the modal dynamic method is almost 37 times more time-consuming than the inertia relief approach, but if accuracy is desired, it can be up to 96% more accurate. Also as predicted, at low frequency loading (less than 10% of the first nonzero frequency of the structure), there is no difference between the results of both methods

Comparison between Isothermal and Non-Isothermal Fatigue Behavior in a Cast Aluminum-Silicon-Magnesium Alloy

Для литого алюмосиликатомагниевого сплава A356.0, широко используемого для изготовления головок цилиндров дизельных двигателей, выполнен сравнительный анализ усталостных процессов при антифазном термомеханическом нагружении, а также при малоцикловом нагружении при комнатной и повышенной температурах. Проведены изотермические и неизотермические циклические испытания с контролем деформаций и температуры, моделирующие эксплуатационные режимы нагружения головок цилиндров.Для литого алюмосилікатомагнієвого сплаву A356.0, що широко використовується для виготовлення головок циліндрів дизельних двигунів, виконано порівняльний аналіз втомних процесів при антифазному термомеханічному навантаженні та при малоцикловому навантаженні за кімнатної і підвищеної температур. Проведено ізотермічні і неізотермічні циклічні випробування з контролем деформацій і температури, що моделюють експлуатаційні режими навантаження головок циліндрів

Finite element analysis of shot-peening effect on fretting fatigue parameters

Shot peening is widely used to improve the fretting fatigue strength of critical surfaces. Fretting fatigue occurs in contacting parts that are subjected to fluctuating loads and sliding movements at the same time. This paper presents a sequential finite element simulation to investigate the shot peening effects on normal stress, shear stress, bulk stress and slip amplitude, which are considered to be the controlling parameters of fretting damage. The results demonstrated that among the modifications related to shot peening, compressive residual stress has a dominant effect on the fretting parameters. (C) 2010 Elsevier Ltd. All rights reserved

Simulation of vehicle body spot weld failures due to fatigue by considering road roughness and vehicle velocity

Durability of the vehicle components needs special attention in the design step due to this fact that the loads on a vehicle are dynamic by their nature. Also, fatigue resistance of the vehicle body is quite important as it is the main load-bearing component among others. The main purpose of the present research is to simulate the spot weld failures of the vehicle body structure due to fatigue damage induced on the body during standardized maneuvers. This was accomplished by using a combination of multi-body dynamics and finite element analyses. To enhance the precision of the analysis, a thickness-dependent nugget diameter was utilized to model the spot welds. To validate the finite element simulations, three-sheet spot-welded specimens were tested and their fatigue lives were compared to numerical results. The findings of this study revealed that the damage to the vehicle body is not always proportional to the vehicle velocity and that depends on the degree of road roughness. Also, the results of simulations showed that the damage to the front part of the body is almost twice the rear part in terms of the number of spot weld failures. The effect of nugget diameter on the fatigue life of the spot welds was also investigated and it was found that the nugget diameter can change the fatigue life of the spot welds up to almost 100%. © 2020 Elsevier B.V

Applications of ultrasonic testing and machine learning methods to predict the static & fatigue behavior of spot-welded joints

Ultrasonic Testing (UT) is one of the well-known Non-Destructive Techniques (NDT) of spot-weld inspection in the advanced industries, especially in automotive industry. However, the relationship between the UT results and strength of the spot-welded joints subjected to various loading conditions is unknown. The main purpose of this research is to present an integrated search system as a new approach for assessment of tensile strength and fatigue behavior of the spot-welded joints. To this end, Resistance Spot Weld (RSW) specimens of three-sheets were made of different types of low carbon steel. Afterward, the ultrasonic tests were carried out and the pulse-echo data of each sample were extracted utilizing Image Processing Technique (IPT). Several experiments (tensile and axial fatigue tests) were performed to study the mechanical properties of RSW joints of multiple sheets. The novel approach of the present research is to provide a new methodology for static strength and fatigue life assessment of three-sheets RSW joints based on the UT results by utilizing Artificial Neural Network (ANN) simulation. Next, Genetic Algorithm (GA) was used to optimize the structure of ANN. This approach helps to decrease the number of tests and the cost of performing destructive tests with appropriat

Shot peening coverage effect on residual stress profile by FE random impact analysis

Shot peening is one of the most effective surface treatments for improving the fatigue strength of machine elements. In this paper, a new finite element-based model to predict the effect of coverage on the surface state is proposed and critically discussed. By this model, the effects of Rayleigh damping, mesh size, and target dimensions on residual stress profile are investigated using a random impingement simulation of shot peening. Moreover, the model enables the realistic simulation of shot peening process with an affordable computational time with respect of present approaches without reducing the number of impacts and analysis accuracy: the computational time was reduced by 25% in comparison with the conventional finite element models using the proposed method. In addition, the required RAM capacity was reduced up to 80% while the calculated residual stresses and the resulting surface roughness are in good agreement with the experimental results

A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and modal dynamic analyses

Owing to the expensive and time-consuming nature of durability experiments, finite element based durability analysis is quite prevalent in the automotive industry. Numerical fatigue life analyses are typically divided into two different categories, the quasi-static methods which are faster and the dynamic methods which are more accurate. The aim of this paper is to compare the inertia relief and modal dynamic approaches in terms of formulation, accuracy and computation time. The chosen case study is the fatigue life of the vehicle body which is considered the main load-bearing component in a vehicle. By utilizing multi-body dynamics model and driving the vehicle on different standardized roads and by different velocities, the loadings, which act on the body are calculated and later used for the stress analysis. Then, by using the structural stress method, the fatigue life of the vehicle spot welds is calculated and the results are compared for both approaches. The findings reveal that the modal dynamic method is almost 37 times more time-consuming than the inertia relief approach, but if accuracy is desired, it can be up to 96% more accurate. Also as predicted, at low frequency loading, there is no major difference between the results of both methods. © 2020 Gruppo Italiano Frattura. All rights reserved

Analysis of Resistance Spot Welding Process Parameters Effect on the Weld Quality of Three-steel Sheets Used in Automotive Industry: Experimental and Finite Element Simulation

In the present research, the effects of spot-welding process parameters on the nugget diameter and electrode penetration depth of spot-welded joints were investigated. To achieve this, a spot-welded joint of three-thin sheet low carbon steels (same thicknesses of 0.8 mm) was simulated as an electerical-thermal-mechanical coupling of 3D finite element model. After validating the finite element simulation presented in this study by comparison with the experimental results for the spot diameter, various cases of spot welds were analyzed based on the design on experiment (i.e., Taguchi method). Six variables including electrode force, electric current, and quadrilateral times (squeeze, up-slope, welding time, and hold) at three different levels were considered as Taguchi algorithm inputs. The results of Taguchi sensitivity analysis showed that the parameters of electrical current (22 %) and welding time (17 %) are the most effective factors on the nugget diameter. Next, Multiple Regression Technique (MRT) was used to present a new equation for calculating spot diameter via the process parameters. The findings of this study showed that the difference between FE results and MRT for predicting spot diameter is less than 13%. Eventually, Response Surface Method (RSM) was utilized to determine the interaction effects of process parameters on the spot weld quality