Multiple-Shot Impact Model for Vibration-Assisted SMAT Process

2022 ◽  
Vol 905 ◽  
pp. 3-8
Author(s):  
Eser Yarar ◽  
Alpay Tamer Erturk
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Equivalent Stress ◽  
High Strength ◽  
Impact Behavior ◽  
Surface Mechanical Attrition Treatment ◽  
Explicit Finite Element ◽  
Plastic Deformation Process ◽  
Multiple Shot ◽  
Explicit Dynamic

Surface mechanical attrition treatment enhances the mechanical properties of metallic materials by inducing high strength layer on the top surface. In this study, multiple-shot impact behavior was modeled for the 7075-T6 aluminum alloy to achieve maximum magnitudes of equivalent stress, plastic strain, residual stress depth, and residual stress. Finite element simulations have been carried out to investigate the effect of selected framework on stress and strains in constituent. The plastic deformation process during SMAT was analyzed using ANSYS/AUTODYN explicit dynamic solver according to shot velocity and diameter with a dynamic explicit finite element method (FEM). Deformation behavior was evaluated after multiple-shot impact.

scholarly journals Finite Element Modeling of Residual Stress at Joint Interface of Titanium Alloy and 17-4PH Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 629
Author(s):  
Nana Kwabena Adomako ◽  
Sung Hoon Kim ◽  
Ji Hong Yoon ◽  
Se-Hwan Lee ◽  
Jeoung Han Kim
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Modeling ◽  
Equivalent Stress ◽  
Stress Gradient ◽  
Joint Interface ◽  
Element Modeling ◽  
Actual Experiment ◽  
Maximum Equivalent Stress

Residual stress is a crucial element in determining the integrity of parts and lifetime of additively manufactured structures. In stainless steel and Ti-6Al-4V fabricated joints, residual stress causes cracking and delamination of the brittle intermetallic joint interface. Knowledge of the degree of residual stress at the joint interface is, therefore, important; however, the available information is limited owing to the joint’s brittle nature and its high failure susceptibility. In this study, the residual stress distribution during the deposition of 17-4PH stainless steel on Ti-6Al-4V alloy was predicted using Simufact additive software based on the finite element modeling technique. A sharp stress gradient was revealed at the joint interface, with compressive stress on the Ti-6Al-4V side and tensile stress on the 17-4PH side. This distribution is attributed to the large difference in the coefficients of thermal expansion of the two metals. The 17-4PH side exhibited maximum equivalent stress of 500 MPa, which was twice that of the Ti-6Al-4V side (240 MPa). This showed good correlation with the thermal residual stress calculations of the alloys. The thermal history predicted via simulation at the joint interface was within the temperature range of 368–477 °C and was highly congruent with that obtained in the actual experiment, approximately 300–450 °C. In the actual experiment, joint delamination occurred, ascribable to the residual stress accumulation and multiple additive manufacturing (AM) thermal cycles on the brittle FeTi and Fe2Ti intermetallic joint interface. The build deflected to the side at an angle of 0.708° after the simulation. This study could serve as a valid reference for engineers to understand the residual stress development in 17-4PH and Ti-6Al-4V joints fabricated with AM.

Modelling shattered rim cracking in railroad wheels

2011 ◽  
Vol 225 (6) ◽  
pp. 593-604
Author(s):  
V Sura ◽  
S Mahadevan
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Equivalent Stress ◽  
Crack Tip ◽  
Residual Stress State

Shattered rim cracking, propagation of a subsurface crack parallel to the tread surface, is one of the dominant railroad wheel failure types observed in North America. This crack initiation and propagation life depends on several factors, such as wheel rim thickness, wheel load, residual stresses in the rim, and the size and location of material defects in the rim. This article investigates the effect of the above-mentioned parameters on shattered rim cracking, using finite element analysis and fracture mechanics. This cracking is modelled using a three-dimensional, multiresolution, elastic–plastic finite element model of a railroad wheel. Material defects are modelled as mathematically sharp cracks. Rolling contact loading is simulated by applying the wheel load on the tread surface over a Hertzian contact area. The equivalent stress intensity factor ranges at the subsurface crack tips are estimated using uni-modal stress intensity factors obtained from the finite element analysis and a mixed-mode crack growth model. The residual stress and wheel wear effects are also included in modelling shattered rim cracking. The analysis results show that the sensitive depth below the tread surface for shattered rim cracking ranges from 19.05 to 22.23 mm, which is in good agreement with field observations. The relationship of the equivalent stress intensity factor (Δ K eq) at the crack tip to the load magnitude is observed to be approximately linear. The analysis results show that the equivalent stress intensity factor (Δ K eq) at the crack tip depends significantly on the residual stress state in the wheel. Consideration of as-manufactured residual stresses decreases the Δ K eq at the crack tip by about 40 per cent compared to that of no residual stress state, whereas consideration of service-induced residual stresses increases the Δ K eq at the crack tip by about 50 per cent compared to that of as-manufactured residual stress state. In summary, the methodology developed in this article can help to predict whether a shattered rim crack will propagate for a given set of parameters, such as load magnitude, rim thickness, crack size, crack location, and residual stress state.

Creep Crack Initiation in a Weld Steel: Effects of Residual Stress

2005 ◽  
Author(s):  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
Farid R. Biglari
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Crack Initiation ◽  
Equivalent Stress ◽  
Stress Triaxiality ◽  
Compact Tension ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Creep Ductility ◽  
Uniaxial Test

In this paper, the effect of residual stress on the initiation of a crack at high temperature in a Type 347 austenitic steel weld is examined using the finite element method. Both two and three dimensional analyses have been carried out. Residual stresses have been introduced by prior mechanical deformation, using a previously developed notched compact tension specimen. It has been found that for the 347 weld material, peak stresses in the vicinity of the notch are approximately three times the yield strength at room temperature and the level of stress triaxiality (ratio between hydrostatic and equivalent stress) is approximately 1 (considerably higher than that for a uniaxial test). The finite element analysis includes the effects of stress redistribution and damage accumulation under creep conditions. For the case examined the analysis predicts that crack initiation will occur under conditions of stress relaxation if the uniaxial creep ductility of the material is less than 2.5%. Furthermore, the predicted life of the component under constant load (creep conditions) is significantly reduced due to the presence of the residual stress field.

scholarly journals Mathematical and Finite Element Modeling of Micro-Modification for Marine Gear

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Xiongxi Wu ◽  
Qifeng Gao ◽  
Zesong Li
Keyword(s):  
Finite Element ◽  
Optimization Design ◽  
Impact Load ◽  
Equivalent Stress ◽  
High Strength ◽  
Transmission Error ◽  
Gear Transmission ◽  
Transmission Model ◽  
Finite Element Software ◽  
Before And After

Based on the computer simulation technique, this paper used the professional gear design software MASTA and finite element software ANSYS combined with the method of gear micro-modification to redesign the gear profile and eventually realized the optimization design of gear micro-modification. Then the gear transmission model of one-level reducer was established to simulate and analyze the contact equivalent stress, transmission error, and meshing impact before and after gear modification. By comparing the simulations results it is found that gear micro-modification can lower meshing impact load, reduce the vibration strength, make gear transmission steady, and improve the gear bearing capacity. By comparing the transmission error curves and meshing impact load curves before and after gear micro-modification, this helps to understand the effects of gear micro-modification on the gear transmission and provides basis references for the future redesign of the marine gears with high strength and long service life.

scholarly journals Finite Element Modelling of Laser Stitch Welding Joints for Structural Dynamic Predictions

2019 ◽  
Vol 16 (2) ◽  
pp. 6556-6567
Author(s):  
M. A. S. Aziz Shah ◽  
M. A. Yunus ◽  
M. N. Abdul Rani ◽  
M. S. Mohd Zin ◽  
W. I. I. Wan Iskandar Mirza
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Dynamic Behaviour ◽  
Welding Process ◽  
Shell Element ◽  
High Strength ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Structural Dynamic ◽  
Welded Structure

Laser stitch welding is a joining technique that has been increasingly popular in automotive industries, such as in the manufacturing and assembling of the car’s body-in-white (BiW) due to its advantages over the resistance spot weld, such as low heat application and high strength weld. The dynamic behaviour of a laser stitch welded structure is relatively difficult to predict accurately due to local parameters being induced during the laser welding process, such as heat affected zone (HAZ) and residual stress in the welded structure. This paper presents the idea of modelling the laser stitch weld by investigating different types of element connectors that can be used to represent laser stitch weld, such as rigid body element (RBE2), shell element (CQUAD4), bar element (CBAR) and area contact model (ACM2) format of element connectors. The accuracy of finite element models of laser stitch welded joints is compared in terms of natural frequencies and mode shapes with the experiment counterparts. The dynamic behaviour of the measured structure is obtained by using an impact hammer with free-free boundary conditions. It is found that the accuracy of the finite element models of the laser stitch welded structure highly depends on the involvement of residual stress and the heat affected zones that are generated from the welding process.

Proposal of the Screening Method for Prevention of the Accumulation of the Ratcheting Strain Derived From the Movement of the Temperature Distribution

2014 ◽  
Author(s):  
Satoshi Okajima ◽  
Takashi Wakai ◽  
Masanori Ando ◽  
Yasuhiro Inoue ◽  
Sota Watanabe
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Finite Element ◽  
Evaluation Method ◽  
Equivalent Stress ◽  
Plastic Region ◽  
Screening Method ◽  
Second Step ◽  
Ratcheting Strain ◽  
Thermal Ratcheting

The prevention of excessive deformation by thermal ratcheting is important in the design of high-temperature components of fast breeder reactors (FBR). This includes evaluation methods for a new type of thermal ratcheting caused by a traveling temperature distribution. Igari et al. [1] proposed a mechanism-based evaluation method to evaluate thermal ratcheting caused by temperature distributions traveling long and short distances. In this paper, we simplify the existing method and propose a screening method to prevent thermal ratcheting strain in the design of practical components. The proposed method consists of two steps to prevent the continuous accumulation of ratcheting strain. The first step is to determine whether all points through the wall thickness are in the plastic state. This is based on an equivalent stress, which comprises the primary stress, the thermal membrane stress, and the thermal bending stress. When the equivalent stress is less than the yield strength of the cylinder material, overall plastic deformation through the wall thickness does not occur. When the equivalent stress exceeds the yield strength in some regions of the cylinder, the ranges of these regions are measured for the second step. To prevent the acceleration of the plastic deformation due to creep, we define the upper limit of the equivalent stress based on the relaxation strength, Sr. The second step is to determine whether the accumulation of the plastic strain saturates (i.e. if shakedown occurs). For this purpose, we define the screening criteria for the range of the plastic region. When the range of the plastic region is sufficiently small, residual stress is generated in the direction opposite to the plastic deformation direction. As a result of residual stress, further accumulation of the plastic deformation is suppressed, and finally shakedown occurs. If the range of the plastic region exceeds the defined criteria, a more detailed evaluation method (e.g. inelastic finite element analysis) may be used for the component design. To validate the proposed method, we performed a set of elasto-plastic finite element method (FEM) analyses, with the assumption of elastic perfectly plastic material.

A Numerical Investigation of a Single-Shot Impact Effects on Plastic Deformation of Titanium Alloys

2021 ◽  
Vol 105 ◽  
pp. 119-124
Author(s):  
Eser Yarar ◽  
A. Tamer Erturk
Keyword(s):  
Plastic Deformation ◽  
Pure Titanium ◽  
Impact Behavior ◽  
Surface Mechanical Attrition Treatment ◽  
Rigid Sphere ◽  
Single Shot ◽  
Commercially Pure Titanium ◽  
The Finite Element Method ◽  
Mechanical Attrition ◽  
Explicit Dynamic

Surface mechanical attrition treatment is a pre-stressing process that enhances the lifespan of mechanical parts. The experimental evaluation of SMAT parameters is not only very complex but also costly. In this study, the single impact behavior of commercially pure titanium and Ti6Al4V alloys is analyzed using the finite element method. For simulating the single-shot impact process, a rigid sphere on a rectangular component is modeled using ANSYS/AUTODYN explicit dynamic solver. The effects of single-shot impact on the induced compressive residual stress and plastic deformation were investigated. Besides, the change in shot velocity after a single shot was revealed by calculating the restitution coefficient, and its relation to plastic deformation was investigated.

scholarly journals Effect of applied load on welding stress at different time periods

2018 ◽  
Vol 224 ◽  
pp. 01069
Author(s):  
Yanhu Wang ◽  
Sergey Konovalov ◽  
Xizhang Chen ◽  
Irina Komissarova
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Applied Load ◽  
Welding Process ◽  
High Strength ◽  
Specific Pressure ◽  
Welding Stress ◽  
Time Periods ◽  
Simulation Results

In this study, pressure finite element welding simulations has been carried out. The welding model is a butt filled weld. The objective is to study the effect of pressure on welding stress of high strength steel at different time periods. From the study we can find that no matter at the first half of welding or and the last half welding or at the cooling time apply the load have little effect to improve the stress. Only under the entire welding process that the distribution of residual stress can be greatly improved. The results show that the residual stresses of the welding workpiece under specific pressure throughout the welding process decreased by 16.2% when compared with weld group without load applied. The maximum residual stresses of weld group without load applied are more than with the specific pressure load plates 120 MPa. But under other times putting the load cannot be improved. This paper just presents a simulation results that have a certain guiding significance.

scholarly journals Finite Element Simulation of the Vibration Provided by Sandwich Rigid Panel with a Resilient Material In Between under Heavyweight Impact

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Shun-Fa Hwang ◽  
Chao-Wen Chen ◽  
Sung-Chin Chung ◽  
Yaw-Shyan Tsay
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Behavior ◽  
Sound Insulation ◽  
Explicit Finite Element ◽  
Element Simulation ◽  
Rubber Model ◽  
Two Parameters ◽  
The Impact ◽  
Impact Vibration

The purpose of the present work is to use an explicit finite element code to model the impact behavior of a heavyweight impact source like rubber ball and to predict the floor impact vibration of resilient materials, which are used in the floor coverings construction for sound insulation. To simulate the impact force of rubber balls, the hyperviscoelastic rubber model is applied. Then, this rubber model is used in the simulation for the impact vibration of resilient materials. The results indicate that the hyperviscoelastic rubber model could precisely simulate the impact force of rubber balls, as its two parameters are properly chosen according to the desired impact force. Also, the present model could capture the impact and vibration behavior of the considered materials and reasonably evaluate the insulation effect of resilient materials.

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