Verification of a Thermoviscoplastic Constitutive Relation for Brass Material Using Taylor's Test

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Farid Abed ◽  
Tomasz Jankowiak ◽  
Alexis Rusinek
Keyword(s):  
Strain Rate ◽  
Dynamic Behavior ◽  
Constitutive Relation ◽  
Split Hopkinson Pressure Bar ◽  
Constitutive Relations ◽  
Strain Curve ◽  
Material Behavior ◽  
Experimental Results ◽  
Face Centered Cubic ◽  
Test Technique

This paper presents a methodology to define and verify the dynamic behavior of materials based on Taylor's test. A brass alloy with a microstructure composed mainly of two pure metals that have two different crystal structures, copper (face-centered cubic (fcc)) and zinc (hexagonal closed-packed (hcp)), is used in this study. A combined approach of different principal mechanisms controlled by the emergence and evolution of mobile dislocations as well as the long-range intersections between forest dislocations is, therefore, adopted to develop accurate definition for its flow stress. The constitutive relation is verified against experimental results conducted at low and high strain rates and temperatures using compression screw machine and split Hopkinson pressure bar (SHPB), respectively. The present model predicted results that compare well with experiments and was capable of simulating the low strain rate sensitivity that was observed during the several static and dynamic tests. The verified constitutive relations are further integrated and implemented in a commercial finite element (FE) code for three-dimensional (3D) Taylor's test simulations. A Taylor's test enables the definition of only one point on the stress–strain curve for a given strain rate using the initial and final geometry of the specimen after impact into a rigid surface. Thus, it is necessary to perform several tests with different geometries to define the complete material behavior under dynamic loadings. The advantage of using strain rate independent brass in this study is the possibility to rebuild the complete process of strain hardening during Taylor's tests by using the same specimen geometry. Experimental results using the Taylor test technique at a range of velocity impacts between 70 m/s and 200 m/s are utilized in this study to validate the constitutive model of predicting the dynamic behavior of brass at extreme conditions.

scholarly journals Nonlinear Dynamic Constitutive Model of Frozen Sandstone Based on Weibull Distribution

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Lei Wang ◽  
Hongming Su ◽  
Shiguan Chen ◽  
Yue Qin
Keyword(s):  
Elastic Modulus ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Soft Rock ◽  
Strain Curve ◽  
Peak Stress ◽  
Experimental Results ◽  
Compression Tests ◽  
Hopkinson Pressure Bar

To obtain the dynamic mechanical properties of frozen sandstone at different temperatures (i.e., 20°C, −10°C, −20°C, and −30°C), dynamic uniaxial compression tests of saturated sandstone are conducted using a split-Hopkinson pressure bar. The experimental results demonstrated that the brittleness of the saturated sandstone increased and its plasticity weakened with a decrease in temperature. The peak strength and dynamic elastic modulus of the sandstone were positively correlated with its strain rate. The peak stress was most sensitive to the strain rate at −10°C, and the elastic modulus was most sensitive to the strain rate at −30°C. According to the evident segmentation characteristics of the obtained stress-strain curve, a viscoelastic dynamic constitutive model considering the strain rate effect and temperature effect is developed; this model combines a nonlinear (or linear) body and a Maxwell body in parallel with a damage body. The applicability of the constitutive model is also verified using experimental data. The fitting results were demonstrated to be in good agreement with the experimental results. Furthermore, the fitting results serve as reference for the study of the constitutive model of weakly cemented soft rock and the construction of roadway freezing methods.

The Effect of Strain Rate on the Material Characteristics of Nickel-Based Superalloy Inconel 718

2007 ◽  
Vol 340-341 ◽  
pp. 283-288 ◽  
Author(s):  
Jung Han Song ◽  
Hoon Huh
Keyword(s):  
Dynamic Response ◽  
High Strain Rate ◽  
Strain Rate ◽  
Turbine Blade ◽  
Inconel 718 ◽  
High Speed ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Experimental Results ◽  
Stress Wave Propagation

The dynamic response of the turbine blade materials is indispensable for analysis of erosions of turbine blades as a result of impulsive loading associated with gas flow. This paper is concerned with the dynamic material properties of the Inconel 718 alloy which is widely used in the high speed turbine blade. The dynamic response at the corresponding level of the strain rate should be acquired with an adequate experimental technique and apparatus due to the inertia effect and the stress wave propagation. In this paper, the dynamic response of the Inconel 718 at the intermediate strain rate ranged from 1/s to 400/s is obtained from the high speed tensile test and that at the high strain rate above 1000/s is obtained from the split Hopkinson pressure bar test. The effects of the strain rate on the dynamic flow stress, the strain rate sensitivity and the failure elongation are evaluated with the experimental results. Experimental results from both the quasi-static and the high strain rate up to 3000/s are interpolated in order to construct the constitutive relation that should be applied to simulate the dynamic behavior of the turbine blade made of the Inconel 718.

Experimental and Numerical Study of Soft Tissue Surrogate Behavior Under Ballistic Loading

2012 ◽  
Author(s):  
Ericka K. Amborn ◽  
Karim H. Muci-Küchler ◽  
Brandon J. Hinz
Keyword(s):  
Soft Tissue ◽  
Constitutive Model ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Constitutive Models ◽  
Material Behavior ◽  
Good Representation

Studying the high strain rate behavior of soft tissues and soft tissue surrogates is of interest to improve the understanding of injury mechanisms during blast and impact events. Tests such as the split Hopkinson pressure bar have been successfully used to characterize material behavior at high strain rates under simple loading conditions. However, experiments involving more complex stress states are needed for the validation of constitutive models and numerical simulation techniques for fast transient events. In particular, for the case of ballistic injuries, controlled tests that can better reflect the effects induced by a penetrating projectile are of interest. This paper presents an experiment that tries to achieve that goal. The experimental setup involves a cylindrical test sample made of a translucent soft tissue surrogate that has a small pre-made cylindrical channel along its axis. A small caliber projectile is fired through the pre-made channel at representative speeds using an air rifle. High speed video is used in conjunction with specialized software to generate data for model validation. A Lagrangian Finite Element Method (FEM) model was prepared in ABAQUS/Explicit to simulate the experiments. Different hyperelastic constitutive models were explored to represent the behavior of the soft tissue surrogate and the required material properties were obtained from high strain rate test data reported in the open literature. The simulation results corresponding to each constitutive model considered were qualitatively compared against the experimental data for a single projectile speed. The constitutive model that provided the closest match was then used to perform an additional simulation at a different projectile velocity and quantitative comparisons between numerical and experimental results were made. The comparisons showed that the Marlow hyperelastic model available in ABAQUS/Explicit was able to produce a good representation of the soft tissue surrogate behavior observed experimentally at the two projectile speeds considered.

scholarly journals A Modified Fractional Maxwell Numerical Model for Constitutive Equation of Mn-Cu Damping Alloy

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2020
Author(s):  
Baoquan Mao ◽  
Rui Zhu ◽  
Zhiqian Wang ◽  
Yuying Yang ◽  
Xiaoping Han ◽  
...  
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Constitutive Relation ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Maxwell Model ◽  
Nonlinear Viscoelastic ◽  
Fractional Maxwell Model ◽  
Hysteretic Characteristics ◽  
Nonlinear Elastic

To better describe its constitutive relation, we need a new constitutive equation for an important nonlinear elastic material, Mn-Cu damping alloy. In this work, we studied the nonlinear and hysteretic characteristics of the stress-strain curve of the M2052 alloy with the uniaxial cyclic tensile test with constant strain rate. The strain rate and amplitude correlations of M2052 resembled those of nonlinear viscoelastic material. Therefore, we created a new constitutive equation for the M2052 damping alloy by modifying the fractional Maxwell model, and we used the genetic algorithm to carry out numerical fitting with MATLAB. By comparing with the experimental data, we confirmed that the new constitutive equation could accurately depict the nonlinear constitutive relation and hysteretic property of the damping alloy. Taken together, this new constitutive equation for Mn-Cu damping alloy based on the fractional Maxwell model can serve as an effective tool for further studies of the constitutive relation of the Mn-Cu damping alloys.

Refined Modeling of Projectile Impact Onto Submerged Structure

2008 ◽  
Author(s):  
Justin Onisoru ◽  
Ovidiu Coman ◽  
Paul Wilson ◽  
George Thomas
Keyword(s):  
Strain Rate ◽  
Structural Integrity ◽  
Initial Conditions ◽  
Safety Issue ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Material Behavior ◽  
Spent Fuel ◽  
The Impact

Structural integrity of spent fuel racks is a critical safety issue in nuclear power stations. The standard approach of evaluating the effects of an impact projectile on a submerged structure, which constitute the start point of the current study, involves three main steps: determination of the conditions just prior to the impact (that are considered as initial conditions for the analysis), setting the mechanism of transferring energy from the projectile to the target structure, and determining how that energy is absorbed by the impacted structure. Usually, the dynamics of the projectile are ideally considered, the influence of the fluid presence is restricted to the determination of the impact velocity and strain rate dependency is limited to choosing a true stress vs. strain curve corresponding to some constant strain rate. Starting from the standard engineering approach, the authors have refined the model considering more realistic dynamics of the projectile, extending the influence of the fluid to the entire analysis and using a more accurate strain rate dependant material behavior. Explicit Finite Element analyses are used in order to incorporate the desired effects.

On the Constitutive Relation for the Reynolds Stresses and the Prandtl-Kolmogorov Hypothesis of Effective Viscosity in Axisymmetric Strained Turbulence

1999 ◽  
Vol 122 (1) ◽  
pp. 48-50 ◽  
Author(s):  
J. Jovanovic´ ◽  
I. Otic´
Keyword(s):  
Strain Rate ◽  
Stress Tensor ◽  
Reynolds Stress ◽  
Constitutive Relation ◽  
Effective Viscosity ◽  
Constitutive Relations ◽  
Reynolds Stresses ◽  
Reynolds Stress Tensor ◽  
The Mean ◽  
Mean Strain

The constitutive relation for the Reynolds stress tensor is considered for turbulence developing in axisymmetric strain fields. It is confirmed that the Reynolds stress tensor is aligned linearly with the mean strain rate. In contrast to the Prandtl-Kolmogorov, hypothesis, the effective viscosity is found to grow in proportion to the anisotropy of turbulence and the length scale based on the magnitude of the mean strain rate. Using invariant theory the effective viscosity is determined for the limiting states of turbulence. Additional analysis of the constitutive relations is supplemented for the dissipation and pressure-strain correlations. It is shown that analytical derivations are in excellent agreement with the data obtained from direct numerical simulations. [S0098-2202(00)02801-7]

Electromagnetic Forming and Perforation of Tubes: Modeling, Simulation, and Validation

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Sagar Pawar ◽  
Dinesh Ray ◽  
Sachin D. Kore ◽  
Arup Nandy
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Electromagnetic Forming ◽  
Material Behavior ◽  
Experimental Results ◽  
Discharge Energy ◽  
Coupled Simulation ◽  
Element Analysis ◽  
Failure Patterns

Abstract Electromagnetic forming and perforation (EMFP) is an innovative practice where magnetic forces are used for simultaneous forming and perforation operation. This method is complex, which involves a high strain rate as well as high transformation velocities. It is carried out in a short duration of time, and it includes multiple operations, which increases the complexity in understanding the shearing and forming behavior of the material. To understand this behavior, coupled and non-coupled simulation models have been developed and compared with experimental results. Material and failure models are used for simulating the material behavior at a high strain rate. At lower discharge energy, the coupled model failed to capture the initiation of perforation, but numerical results are found 96% in agreement with experimental results. While on the other hand, on the same discharge energy, non-coupled simulation shows 94% agreement and it succeeded in capturing the initiation of perforation. The von-Mises stresses found in all cases are more than 4e+08 Pa which is found higher than the ultimate strength of the material which is resulting in shearing. The failure patterns obtained in finite element analysis (FEA) simulation for both pointed and concave punch perforation show good agreement with general finding in experiments which shows the prediction capability of developed models.

Mechanical Behavior of Sn1Ag0.5Cu and Sn3Ag0.5Cu Alloys at High Strain Rates

2012 ◽  
Author(s):  
Pradeep Lall ◽  
Sandeep Shantaram ◽  
Jeff Suhling ◽  
David Locker
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Prolonged Exposure ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Image Correlation ◽  
Constitutive Behavior ◽  
Strain Rates ◽  
High Strain Rates ◽  
Test Technique

Electronics may experience high strain rates when subjected to high g-loads of shock and vibration. Material and damage behavior of electronic materials at high strain rates typical of shock and vibration is scarce. Previously studies have shown that second-level interconnects have a high propensity for failure under shock and vibration loads in fine pitch electronics. Exposure to shock and vibration is common in a variety of consumer environments such as automotive and portable electronics. The low strain-rate properties of commonly used SnAgCu solders, including Sn1Ag0.5Cu and Sn3Ag0.5Cu, have been found to evolve with time after prolonged exposure to high temperatures. High strain rate properties of leadfree solder alloys in the strain-rate range of 1–100 sec−1 are scarce. Previous attempts at characterizing the high strain rates properties have focused on the use of the Split Hopkinson Pressure Bar (SHPB), which enables measurements of strain rates in the neighborhood of 1000 per sec. In this paper, a new test-technique developed by the authors has been presented for measurement of material constitutive behavior. The instrument enables attaining strain rates in the neighborhood of 1 to 100 per sec. Tests are conducted at strain rates 10, 35 and 50 per sec. High speed cameras operating at 75,000 fps have been used in conjunction with digital image correlation for the measurement of full-field strain during the test. Constancy of cross-head velocity has been demonstrated during the test from the unloaded state to the specimen failure. Solder alloy constitutive behavior has been measured for SAC105, SAC305 solders. Non-linear Ramberg-Osgood model has been used to fit the material data. The Ramberg-Osgood model available in Abaqus has been used for tensile test simulation and to correlate with DIC based experimental strain data.

Experimental and Physical-Based Constitutive Model Study of FCC Metal Over Wide Temperature and Strain Rate Ranges

2015 ◽  
Author(s):  
Jianchao Yu ◽  
Gang Wang ◽  
Jianwei Qin ◽  
Maobing Shuai ◽  
Yiming Rong
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
True Strain ◽  
Experimental Results ◽  
Deformation Behaviors ◽  
Fcc Metal

Dynamic deformation behaviors of aluminum alloy Al1060 (FCC metal) are studied by the uniaxial compression tests on the Split Hopkinson Pressure Bar over wide temperature and strain rate ranges. The experimental results show that the flow stress is both strain rate and temperature sensitivity. The flow stress decreases with increasing temperature when the strain rate keeps constant. When the temperature keeps constant, the flow stress increases with increasing strain rate. Considering the thermal activation of dislocation gliding in the dynamic deformation process, a physical-based constitutive model is developed based on the experimental results to predict the flows stress of Al1060 at a given strain rate and temperature. The material constants in the constitutive model are determined by the nonlinear genetic algorithm. The true stress-true strain curves predicted by the proposed constitutive models can give good correlations with the experimental results, which confirm that the proposed physical-based constitutive can accurately characterize the dynamic deformation behaviors of the studied aluminum alloy Al1060.

Singular Fields in Plane-Strain Penetration

1991 ◽  
Vol 58 (4) ◽  
pp. 910-915 ◽  
Author(s):  
David Durban ◽  
Omri Rand
Keyword(s):  
Boundary Layer ◽  
Strain Rate ◽  
Plane Strain ◽  
Constitutive Relation ◽  
Solid Material ◽  
Material Behavior ◽  
Wall Friction ◽  
Friction Factors ◽  
Hardening Parameter ◽  
Strain Rate Hardening

Local singular fields are investigated in the vicinity of the vertex of a sharp wedge that penetrates a viscous solid. Material behavior is modeled by the usual powerlaw constitutive relation. Wall friction is accounted for by imposing friction factors along the walls of the wedge. The case of a Newtonian fluid is investigated analytically, and sample numerical results are presented for nonlinear strain rate hardening. It is shown that the exponent of strain rate singularity increases as the wedge becomes sharper and smoother. Increasing the hardening parameter also results in a stronger strain rate singularity. High levels of wall friction induce an intensive shear boundary layer near the wall.

Sign in / Sign up

Export Citation Format

Share Document