JOHNSON–COOK MODEL COMBINED WITH COWPER–SYMONDS MODEL FOR BONE CUTTING SIMULATION WITH EXPERIMENTAL VALIDATION

2021 ◽  
Vol 21 (02) ◽  
pp. 2150010
Author(s):  
VARATHARAJAN PRASANNAVENKADESAN ◽  
PONNUSAMY PANDITHEVAN
Keyword(s):  
Cutting Force ◽  
Constitutive Models ◽  
Percentage Error ◽  
Bovine Bone ◽  
Strain Rates ◽  
Combined Model ◽  
Cutting Simulation ◽  
Lack Of Information ◽  
Experimental Cutting ◽  
Cook Model

Constitutive models are widely used to predict the mechanical behavior of different kinds of materials. Although the Johnson–Cook model for bovine bone and Cowper–Symonds model for human thoracic rib and tibia was developed, the predictability of these models was found good only at particular strain rates. This study addresses this lack of information by investigating the Cowper–Symonds model, Johnson–Cook model, and Johnson–Cook model combined with Cowper–Symonds model at different strain rates to utilize in the bone cutting simulation. Specimens prepared using two rear femurs harvested from a 3.50-year-old bovine were investigated at different strain rates (0.00001–1/s). A comparative study made among the stresses predicted from these models showed 29.41%, 10.91%, and 11.11% mean absolute percentage errors using Cowper–Symonds model, and 2.03%, 7.19%, and 3.62% mean absolute percentage errors using Johnson–Cook model, respectively, at 0.0001, 0.001 and 1/s strain rates. However, the Johnson–Cook model combined with the Cowper–Symonds model predicted the stress with a maximum of only 2.03% mean absolute percentage error. The potential of each model to utilize in the orthogonal bone cutting was also evaluated using Ansys® and found that the combined model predicted the cutting force close to experimental cutting force with minimal error (5.20%). The outcomes of this study can be used in the surgical practice and osteotomy procedure before commencing actual surgery.

Modified Johnson-Cook model of aluminum alloy 6016-T6 sheets at low dynamic strain rates

2021 ◽  
pp. 141565
Author(s):  
Zhe Jia ◽  
Ben Guan ◽  
Yong Zang ◽  
Yuan Wang ◽  
Lei Mu
Keyword(s):  
Aluminum Alloy ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Cook Model

Simulation of Machining of Incoloy 907 Based on Thermodynamical Constitutive Equation

2013 ◽  
Vol 631-632 ◽  
pp. 681-685
Author(s):  
Fang Shao ◽  
Fa Qing Li ◽  
Hai Ying Zhang ◽  
Xuan Gao
Keyword(s):  
Cutting Force ◽  
Cutting Temperature ◽  
Tool Material ◽  
High Reactivity ◽  
Good Prediction ◽  
Workpiece Material ◽  
Element Analysis ◽  
Good Prediction Accuracy ◽  
Experimental Cutting ◽  
Cutting Tool Materials

Aero-engine alloys (also as known as superalloys)are known as difficult-to-machine materials, especially at higher cutting speeds, due to their several inherent properties such as low thermal conductivity and their high reactivity with cutting tool materials. In this paper a finite element analysis (FEA) of machining for Incoloy907 is presented. In particular, the thermodynamical constitutitve equation(T-C-E) in FEA is applied for both workpiece material and tool material. Cutting temperature and cutting force are predicted. The comparison between the predicted and experimental cutting temperature and cutting force are presented and discussed. The results indicated that a good prediction accuracy of both principal cutting temperature and cutting force can be achieved by the method of FEA with thermodynamical constitutitve equation.

scholarly journals Identification of orthotropic material parameters for acute, necrotic, fibrotic and remodelling myocardial infarcts in the rat

2019 ◽  
Author(s):  
Mazin S. Sirry ◽  
Laura Dubuis ◽  
Neil H. Davies ◽  
Jun Liao ◽  
Thomas Franz
Keyword(s):  
Constitutive Model ◽  
Orthotropic Material ◽  
Constitutive Models ◽  
Biaxial Stress ◽  
Percentage Error ◽  
Fe Model ◽  
Stress Strain ◽  
Material Parameters ◽  
Strain Data ◽  
Tensile Experiment

AbstractFinite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

Prediction of Cutting Force in Bone Cutting Using Finite Element Analysis

2021 ◽  
Author(s):  
Varatharajan Prasannavenkadesan ◽  
Ponnusamy Pandithevan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cutting Force ◽  
Material Model ◽  
Tensile Tests ◽  
Bovine Bone ◽  
Element Analysis ◽  
Cutting Processes ◽  
Parameter Values ◽  
First Time

Abstract In orthopedic surgery, bone cutting is an indispensable procedure followed by the surgeons to treat the fractured and fragmented bones. Because of the unsuitable parameter values used in the cutting processes, micro crack, fragmentation, and thermal osteonecrosis of bone are observed. Therefore, prediction of suitable cutting force is essential to subtract the bone without any adverse effect. In this study, the Cowper-Symonds model for bovine bone was developed for the first time. Then the developed model was coupled with the finite element analysis to predict the cutting force. To determine the model constants, tensile tests with different strain rates (10−5/s, 10−4/s, 10−3/s, and 1/s) were conducted on the cortical bone specimens. The developed material model was implemented in the bone cutting simulation and validated with the experiments.

Comparative studies of the constitutive models for tungsten heavy alloy (95W-3.5Ni-1.5Fe) at high strain rates

2021 ◽  
pp. 095440622110451
Author(s):  
Xiuwen Lai ◽  
Zhanjiang Wang ◽  
Na Qin
Keyword(s):  
Threshold Stress ◽  
Dynamic Compression ◽  
Constitutive Models ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Strain Rates ◽  
Stress Model ◽  
Static Compression ◽  
Mechanical Threshold ◽  
Wide Range

The plastic behaviors’ description of a tungsten heavy alloy (95W-3.5Ni-1.5Fe) at temperatures of 298–773 K and strain rates of 0.001–11,000 s−1 is systematically studied based on four constitutive models, that is, Zerilli-Armstrong model, modified Zerilli-Armstrong model, Mechanical Threshold Stress model, and modified Mechanical Threshold Stress model. The quasi-static compression experiments using an electronic universal testing machine and the dynamic compression experiments using a split Hopkinson pressure bar apparatus are employed to obtain the true stress–strain curves at a total of three temperatures (298 K, 573 K, and 773 K) and a wide range of strain rates (0.001–11,000 s−1). The parameters of the four constitutive models are obtained by the above fundamental experimental data and Grey Wolf Optimizer. The correlation coefficient and average absolute relative error are used to evaluate the predicted performance of these models. Modified Mechanical Threshold Stress model is found to have the highest predicted performance in describing the flow stress of the 95W-3.5Ni-1.5Fe alloy. Eventually, two compression experiments whose loading conditions are not in the fundamental experiments are conducted to validate the four models.

scholarly journals A Comparative Study on Johnson Cook, Modified Zerilli–Armstrong, and Arrhenius-Type Constitutive Models to Predict Compression Flow Behavior of SnSbCu Alloy

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1726 ◽  
Author(s):  
Tongyang Li ◽  
Bin Zhao ◽  
Xiqun Lu ◽  
Hanzhang Xu ◽  
Dequan Zou
Keyword(s):  
Experimental Data ◽  
Flow Behavior ◽  
Constitutive Models ◽  
Strain Range ◽  
Type Model ◽  
Strain Rates ◽  
Compression Tests ◽  
Predictive Values ◽  
Specific Strain ◽  
Optimum Model

The flow behavior of the SnSbCu alloy is studied experimentally by the compression tests in the range of the strain rates from 0.0001 to 0.1 s−1 and temperature from 293 to 413 K. Based on the experimental data, three constitutive models including the Johnson–Cook (J–C), modified Zerilli–Armstrong (Z–A), and Arrhenius-type (A-type) models are compared to find out an optimum model to describe the flow behavior of the SnSbCu alloy. The results show that the J–C model could predict the flow behavior of the SnSbCu alloy accurately only at some specific strain rates and temperature near the reference values. The modified Z–A and A-type constitutive models can give better fitting results than the J–C model. While, at high strains, the predictive values of the modified Z–A model have larger errors than those at low strains, which means this model has limitations at high strains. By comparison, the A-type model could predict the experimental results accurately at the whole strain range, which indicates that it is a more suitable choice to describe the flow behavior of the SnSbCu alloy in the focused range of strain rates and temperatures. The work is beneficial to solve the tribological problem of the bearing of the marine engine by integrating the accurate constitutive model into the corresponding numerical model.

Constitutive Modeling for the Prediction of Peak Stress in Hot Deformation Processing of Al Alloy Based Nanocomposite

2011 ◽  
Vol 328-330 ◽  
pp. 1602-1605 ◽  
Author(s):  
V. Senthilkumar ◽  
A. Balaji Abhishek ◽  
Hafeez Ahamed
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Constitutive Modeling ◽  
Hot Deformation ◽  
Constitutive Models ◽  
Peak Stress ◽  
Percentage Error ◽  
Al Alloy ◽  
Measured Flow ◽  
Deformation Tests

Hot deformation tests were carried out on Al5083 – 2 %(vol) TiC nanocomposite in a temperature range of 250 – 450°C at varying strain rate of 0.01 – 1.0 sec-1. Constitutive models were developed for the prediction of peak flow stress relating strain rate, true stress, temperature and activation energy. The percentage error between measured flow stress and constitutive model values were calculated to analyse the efficacy of the model in the prediction of peak stress. Finally, a window of working of the selected nanocomposite is established for finding out the safer region of working.

Method for validating CT length measurement of cracks inside solder joints

2016 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Tamás Garami ◽  
Oliver Krammer ◽  
Gábor Harsányi ◽  
Péter Martinek
Keyword(s):  
High Resolution ◽  
Crack Length ◽  
Solder Joints ◽  
Life Time ◽  
Percentage Error ◽  
Content Type ◽  
Lack Of Information ◽  
Length Measurements ◽  
Set Up ◽  
Ct Measurement

Purpose – This paper aims to develop a method to measure the length of cracks inside solder joints, which enables the validation of computed tomography (CT) crack length measurements. Design/methodology/approach – Cracks were formed inside solder joints intentionally by aging solder joints of 0603 size resistors with thermal shock (TS) test (−40 to +140°C, 2,000 cycles), and CT images were captured about them with different rotational increment (1/4, 1/2 and 1°) of sample projection. The length of cracks was also measured with our method, which is based on capturing high-resolution radiography X-ray images about the cracks in two perpendicular projection planes. The radiography results were compared to the CT measurements. The percentage error for the different CT rotational increment settings was calculated, and the optimal CT settings have been determined. Findings – The results have proven that reducing the rotational increment increases the sharpness of the captured images and the accuracy of crack length measurements. Nevertheless, the accuracy compared to high-resolution radiography measurements is only slightly better at 1/4° rotational increment than in the case of 1/2° rotational increment. It should be also noted that the 1/4° increment requires twice as much time for capturing the images as the 1/2° increment. So, the 1/2° rotational increment of sample projection is the optimal setting in our investigated case for measuring crack lengths. Practical implications – The developed method is applicable to find the optimal settings for CT crack length measurements, which provides faster analysation of large quantity samples used, e.g. at life-time tests. Originality/value – There is a lack of information in the literature regarding the optimisation of CT measurement set-up, e.g. a slightly larger value of the sample rotational increment can provide acceptable resolution with much faster processing time. Thus, the authors developed a method and performed research about optimising CT measurement parameters.

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