Effect of plastic strain and ductile damage on elastic modulus of multiphase steel and its impact on springback prediction

2019 ◽  
Author(s):  
Sebastian Münstermann ◽  
Yannik Sparrer ◽  
Yuan Yao ◽  
Junhe Lian ◽  
Rickmer Meya ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Ductile Damage ◽  
Multiphase Steel ◽  
Springback Prediction

scholarly journals Description of Residual Stress and Strain Fields in FGM Hollow Disc Subject to External Pressure

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 440 ◽  
Author(s):  
Stanislav Strashnov ◽  
Sergei Alexandrov ◽  
Lihui Lang
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Yield Stress ◽  
Plastic Region ◽  
External Pressure ◽  
Plastic Strain Rate ◽  
Constant Thickness ◽  
Stress And Strain ◽  
Strain Fields ◽  
Tensile Yield Stress

Elastic/plastic stress and strain fields are obtained in a functionally graded annular disc of constant thickness subject to external pressure, followed by unloading. The elastic modulus and tensile yield stress of the disc are assumed to vary along the radius whereas the Poisson’s ratio is kept constant. The flow theory of plasticity is employed. However, it is shown that the equations of the associated flow rule, which are originally written in terms of plastic strain rate, can be integrated with respect to the time giving the corresponding equations in terms of plastic strain. This feature of the solution significantly facilitates the solution. The general solution is given for arbitrary variations of the elastic modulus and tensile yield stress along the radial coordinate. However, it is assumed that plastic yielding is initiated at the inner radius of the disc and that no other plastic region appears in the course of deformation. The solution in the plastic region at loading reduces to two ordinary differential equations. These equations are solved one by one. Unloading is assumed to be purely elastic. This assumption should be verified a posteriori. An illustrative example demonstrates the effect of the variation of the elastic modulus and tensile yield stress along the radius on the distribution of stresses and strains at the end of loading and after unloading. In this case, it is assumed that the material properties vary according to power-law functions.

scholarly journals Effect of Elastic Module Degradation Measurement in Different Sizes of the Nonlinear Isotropic–Kinematic Yield Surface on Springback Prediction

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 511 ◽  
Author(s):  
Baara ◽  
Baharudin ◽  
Anuar ◽  
Ismail
Keyword(s):  
Residual Stress ◽  
Elastic Modulus ◽  
Kinematic Hardening ◽  
Strain Recovery ◽  
Final Shape ◽  
Hardening Model ◽  
New Model ◽  
Finite Element Software ◽  
Yield Surfaces ◽  
Springback Prediction

Commercial finite element software that uses default hardening model simulation is not able to predict the final shape of sheet metal that changes its dimensions after removing the punch due to residual stress (strain recovery or springback). We aimed to develop a constitutive hardening model to more accurately simulate this final shape. The strain recovery or balancing of residual stress can be determined using the isotropic hardening of the original elastic modulus and the hardening combined with varying degrees of elastic modulus degradation and the size of the yield surfaces. The Chord model was modified with one-yield surfaces. The model was combined with nonlinear isotropic–kinematic hardening models and implemented in Abaqus user-defined material subroutine for constitutive model (UMAT). The Numisheet 2011 benchmark for springback prediction for DP780 high-strength steel sheet was selected to verify the new model, the Chord model, the Quasi Plastic-Elastic (QPE) model, and the default hardening model using Abaqus software. The simulation of U-draw bending from the Numisheet 2011 benchmark was useful for comparing the proposed model with experimental measurements. The results from the simulation of the model showed that the new model more accurately predicts springback than the other models.

Effects of Plastic Strain on Mechanical and Electrical Conductivity Response of (100) Monocrystalline Copper

2020 ◽  
Vol 12 (7) ◽  
pp. 1004-1011
Author(s):  
Lijia Li ◽  
Dan Zhao ◽  
Xingdong Sun ◽  
Shunbo Wang ◽  
Yue Guo ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Elastic Modulus ◽  
Plastic Strain ◽  
Contact Area ◽  
Recovery Rate ◽  
Plastic Region ◽  
Maximum Load ◽  
Quantitative Relation ◽  
Total Work ◽  
Strain Sensing

The physical characteristics of material would be influenced by its stress states. In this paper, nanoindentation experiments with a maximum load of 100 mN and strain-sensitive resistance tests were conducted on (100) monocrystalline copper with tension-induced plastic strain to investigate the influences of plastic strain on mechanical and electrical characteristics. By theoretical and experimental analysis, indentation depth, elastic modulus, recovery rate of total work, contact area, pile-up and apparent hardness of the deformed and virgin material were obtained and the corresponding investigation was compared and analyzed. The experimental results revealed that under the same conditions, tensile pre-deformed material would like to generate more penetration depth to achieve the same load during indentation. As the plastic strain increased in the uniform plastic region, both the total and elastic indentation work increased, while the recovery rate of total work, contact area, apparent hardness, and elastic modulus decreased. Meanwhile, the contribution of plastic strain to electrical resistivity was also investigated. The quantitative relation between electrical resistivity and plastic strains was extracted from experiments. The understanding of the role of plastic strain in mechanical and electrical properties of monocrystalline copper would be helpful to the application in damage detection systems and strain sensing sensor.

Elastic Modulus Model Based on Dislocation Density and its Application on Aluminum Alloy 5052

2016 ◽  
Vol 725 ◽  
pp. 659-664
Author(s):  
Hai Yan Yu ◽  
Chen Xiao Zhou
Keyword(s):  
Experimental Data ◽  
Aluminum Alloy ◽  
Elastic Modulus ◽  
Dislocation Density ◽  
Plastic Strain ◽  
Tensile Tests ◽  
Proposed Model ◽  
Non Linear ◽  
Maximum Decrease ◽  
Simulation Error

An elastic modulus model is proposed to describe the phenomenon of the material’s elastic modulus varying with plastic strain. This elastic modulus model is theoretically interpreted using the dislocation density as an internal variant. Loading-unloading-reloading (LUR) tensile tests have been implemented to analyze the non-linear unloading behavior. The maximum decrease of the elastic modulus of AA5052 is approximately 16%. The proposed model is introduced into the springback simulation of U-bending. The results showed that the contour of springback simulation with the proposed elastic modulus model is closer to that of the experimental data than results of constant elastic modulus simulation. Error in the springback simulation with the proposed elastic modulus model can be reduced by up to 20% compared with that predicted with a constant elastic modulus.

scholarly journals Effects of Hardening Model and Variation of Elastic Modulus on Springback Prediction in Roll Forming

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1005 ◽  
Author(s):  
Naofal ◽  
Naeini ◽  
Mazdak
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Kinematic Hardening ◽  
Roll Forming ◽  
Isotropic Hardening ◽  
Plastic Behavior ◽  
Forming Process ◽  
Hardening Models ◽  
Springback Prediction ◽  
Roll Forming Process

In this paper, the uniaxial loading–unloading–reloading (LUR) tensile test was conducted to determine the elastic modulus depending on the plastic pre-strain. To obtain the material parameters and parameter of Yoshida-Uemori’s kinematic hardening models, tension–compression experiments were carried out. The experimental results of the cyclic loading tests together with the numerically predicted response of the plastic behavior were utilized to determine the parameters using the Ls-opt optimization tool. The springback phenomenon is a critical issue in industrial sheet metal forming processes, which could affect the quality of the product. Therefore, it is necessary to represent a method to predict the springback. To achieve this aim, the calibrated plasticity models based on appropriate tests (cyclic loading) were implemented in commercial finite element (FE) code Ls-dyna to predict the springback in the roll forming process. Moreover, appropriate experimental tests were performed to validate the numerical results, which were obtained by the proposed model. The results showed that the hardening models and the variation of elastic modulus have significant impact on springback accuracy. The Yoshida-Uemori’s hardening represents more accurate prediction of the springback during the roll forming process when compared to isotropic hardening. Using the chord modulus to determine the reduction in elastic modulus gave more accurate results to predict springback when compared with the unloading and loading modulus to both hardening models.

scholarly journals Effects of backfill soil on pipeline’s mechanical response subjected to perilous rock impact

2020 ◽  
Vol 40 (1) ◽  
pp. 25-31
Author(s):  
Jie Zhang ◽  
Wei Guo ◽  
Haiyang Li
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Low Velocity Impact ◽  
Soil Parameters ◽  
Buried Pipeline ◽  
Velocity Impact ◽  
Backfill Soil

Perilous rock impact is one of the most serious geological disasters that threats to buried pipeline security. Mechanical behavior of buried pipeline in rock stratum impacted by perilous rock was simulated in this paper. And effects of impact velocity and backfill soil parameters on stress and strain of pipeline were discussed. The resluts show that cross section shape of pipeline is oval when impact velocity is small. Impact dent appears on pipeline with the increasing of impact velocity, buckling is more serious and plastic stain increases. Under low velocity impact, stress and plastic strain decrease with the increasing of soil's elastic modulus. Plastic strain increases first and then decreases with the increasing of soil's Poisson's ratio. With the increasing of soil's cohesion, plastic strain increases, but stress first increases and then decreases. Under high velocity impact, deformation and plastic strain increase with the decreasing of elastic modulus and Poisson's ratio. But cohesion has a small effect on buckling behavior of pipeline.

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