scholarly journals Analysis of Impact Energy to Fracture Unnotched Charpy Specimens Made From Railroad Tank Car Steel

2007 ◽  
Author(s):  
H. Yu ◽  
D. Y. Jeong ◽  
J. E. Gordon ◽  
Y. H. Tang
Keyword(s):  
Test Data ◽  
Impact Energy ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Equivalent Strain ◽  
Strain Criterion ◽  
Element Analysis ◽  
Damage And Failure ◽  
Failure Modeling ◽  
The Impact

This paper describes a nonlinear finite element analysis (FEA) framework that examines the impact energy to fracture unnotched Charpy specimens by an oversized, nonstandard pendulum impactor called the Bulk Fracture Charpy Machine (BFCM). The specimens are made from railroad tank car steel, have different thicknesses and interact with impact tups with different sharpness. The FEA employs a Ramberg-Osgood equation for plastic deformations. Progressive damage and failure modeling is applied to predict initiation and evolution of fracture and ultimate material failure. Two types of fracture initiation criterion, i.e., the constant equivalent strain criterion and the stress triaxiality dependent equivalent strain criterion, are compared in material modeling. The impact energy needed to fracture a BFCM specimen is calculated from the FEA. Comparisons with the test data show that the FEA results obtained using the stress triaxiality dependent fracture criterion are in excellent agreement with the BFCM test data.

Response of Mild Steel Pipes Under High Mass Low Velocity Impacts

2014 ◽  
Author(s):  
Shamsoon Fareed ◽  
Ian May
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Impact Energy ◽  
High Mass ◽  
Low Velocity ◽  
Element Analysis ◽  
Steel Pipes ◽  
Impact Tests ◽  
The Finite Element Analysis ◽  
The Impact

Accidental loads, for example, due to heavy dropped objects, impact from the trawl gear and anchors of fishing vessels can cause damage to pipelines on the sea bed. The amount of damage will depend on the impact energy. The indentation will be localized at the contact area of the pipe and the impacting object, however, an understanding of the extent of the damage due to an impact is required so that if one should occur in practice an assessment can be made to determine if remedial action needs to be taken to ensure that the pipeline is still serviceable. There are a number of parameters, including the pipe cross section and impact energy, which influence the impact behaviour of a pipe. This paper describes the response, and assesses the damage, of mild steel pipes under high mass low velocity impacts. For this purpose full scale impacts tests were carried out on mild steel pipe having diameter of 457 mm, thickness of 25.4 mm and length of 2000 mm. The pipe was restrained along the base and a 2 tonnes mass with sharp impactor having a vertical downward velocity of 3870 mm/sec was used to impact the pipe transversely with an impact energy of 16 kJ. It was found from the impact tests that a smooth indentation was produced in the pipe. The impact tests were then used for validation of the non-linear dynamic implicit analyses using the finite element analysis software ABAQUS. Deformations at the impact zone, the rebound velocity, etc, recorded in the tests and the results of the finite element analysis were found to be in good agreement. The impact tests and finite element analyses described in this paper will help to improve the understanding of the response of steel pipes under impact loading and can be used as a benchmark for further finite element modelling of impacts on pipes.

scholarly journals Finite Element Analysis of Impact Energy on Spur Gear

2018 ◽  
Vol 225 ◽  
pp. 06011 ◽  
Author(s):  
Ismail Ali Bin Abdul Aziz ◽  
Daing Mohamad Nafiz Bin Daing Idris ◽  
Mohd Hasnun Arif Bin Hassan ◽  
Mohamad Firdaus Bin Basrawi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Energy ◽  
High Speed ◽  
Impact Test ◽  
Impact Load ◽  
Gear Tooth ◽  
Test Equipment ◽  
Element Analysis ◽  
The Impact

In high-speed gear drive and power transmission, system impact failure mode always occurs due to the sudden impact and shock loading during the system in running. Therefore, study on the amount of impact energy that can be absorbed by a gear is vital. Impact test equipment has been designed and modelled for the purpose to study the impact energy on gear tooth. This paper mainly focused on Finite Element Analysis (FEA) of impact energy that occurred during simulation involving the impact test equipment modelling. The simulation was conducted using Abaqus software on critical parts of the test equipment to simulate the impact event and generate impact data for analysis. The load cell in the model was assumed to be free fall at a certain height which gives impact load to the test gear. Three different type of material for the test gear were set up in this simulation. Results from the simulation show that each material possesses different impact energy characteristic. Impact energy values increased along with the height of load drop. AISI 1040 were found to be the toughest material at 3.0m drop that could withstand up to 44.87N.m of impact energy. These data will be used to validate data in physical experiments in further study.

Evaluation of prediction error resulting from using average state variables in the calibration of ductile fracture criterion

2017 ◽  
Vol 27 (8) ◽  
pp. 1231-1251 ◽  
Author(s):  
Xincun Zhuang ◽  
Yehui Meng ◽  
Zhen Zhao
Keyword(s):  
Ductile Fracture ◽  
Prediction Error ◽  
Fracture Criterion ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Equivalent Strain ◽  
State Variables ◽  
Ductile Fracture Criterion ◽  
Series Of Experiments ◽  
Relationship Of

In order to evaluate the prediction error resulting from using average state variables in the calibration procedure of the ductile fracture criterion, a series of experiments and corresponding simulations were performed to extract the evolution of fracture-related state variables such as stress triaxiality (η), Lode parameter, and equivalent strain to fracture at the fracture initiation points. The average stress triaxiality, average Lode parameter, and equivalent strain to fracture were used to calibrate the Lou-Huh (L-H) ductile fracture criterion. The average induced prediction error was evaluated by comparing the accumulated damage value, which was computed with the calibrated L-H ductile fracture criterion at the fracture initiation point, with the critical threshold value. Comparisons based on a series of experiments covering a wide range of values for stress triaxiality indicated the existence of an average induced prediction error for the compression tests, and demonstrated that different values of embedded-constants C1 and C2 of L-H ductile fracture criterion resulted in entirely different average induced prediction errors. Thus, a parameter study was performed to investigate the influences of C1, C2, the relationship of η and equivalent plastic strain ([Formula: see text]), and the internal function of the integral formula on the average induced relative error. The influence of the relationship of [Formula: see text] could be represented by the influence of the exponent a, the intercept for the stress triaxiality, and the allocation of equivalent strain for the segmented function. Among these influence factors, the value of C2, the value of the exponent a, and the value of the negative intercept for stress triaxiality contributed significantly to an increase in relative error.

Ductile Fracture Modeling of DH36 Grade Steels

2018 ◽  
Author(s):  
Burak Can Cerik ◽  
Sung-Ju Park ◽  
Joonmo Choung
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Surface ◽  
Ductile Fracture ◽  
Stress Triaxiality ◽  
Local Stress ◽  
Fracture Initiation ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Element Analysis

A Hosford-Coulomb type ductile fracture surface was developed for DH36 grade steels. The fracture experiments reported in the literature, which consist of tests with notched tensile specimens, tensile specimens with a central hole, shear specimen and disc specimens for punch specimens, were utilized in a detailed finite element analysis of each experiment to evaluate the evolution of local stress and strain fields and identify plasticity and fracture response of DH36. The developed plasticity model consists of a von Mises yield surface, an associated flow rule and a combined Swift-Voce type isotropic hardening rule. The loading paths to fracture initiation were determined in terms of stress triaxiality and normalized Lode angle parameter histories. Finally, the Hosford-Coulomb fracture surface was calibrated using the finite element analysis results and adapting a linear damage accumulation law.

scholarly journals On Characteristics of Ferritic Steel Determined during the Uniaxial Tensile Test

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3117
Author(s):  
Ihor Dzioba ◽  
Sebastian Lipiec ◽  
Robert Pala ◽  
Piotr Furmanczyk
Keyword(s):  
Tensile Test ◽  
Test Data ◽  
Constitutive Relationship ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Element Analysis ◽  
Material Weakness ◽  
Uniaxial Test ◽  
The Impact ◽  
Tensile Test Data

Tensile uniaxial test is typically used to determine the strength and plasticity of a material. Nominal (engineering) stress-strain relationship is suitable for determining properties when elastic strain dominates (e.g., yield strength, Young’s modulus). For loading conditions where plastic deformation is significant (in front of a crack tip or in a neck), the use of true stress and strain values and the relationship between them are required. Under these conditions, the dependence between the true values of stresses and strains should be treated as a characteristic—a constitutive relationship of the material. This article presents several methodologies to develop a constitutive relationship for S355 steel from tensile test data. The constitutive relationship developed was incorporated into a finite element analysis of the tension test and verified with the measured tensile test data. The method of the constitutive relationship defining takes into account the impact of high plastic strain, the triaxiality stress factor, Lode coefficient, and material weakness due to the formation of microvoids, which leads to obtained correctly results by FEM (finite elements method) calculation. The different variants of constitutive relationships were applied to the FEM loading simulation of the three-point bending SENB (single edge notched bend) specimen to evaluate their applicability to the calculation of mechanical fields in the presence of a crack.

A theoretical analysis on the failure of unpressurized and pressurized pipelines

2002 ◽  
Vol 216 (3) ◽  
pp. 151-165 ◽  
Author(s):  
W Q Shen ◽  
D W Shu
Keyword(s):  
Theoretical Analysis ◽  
Impact Energy ◽  
Empirical Formula ◽  
Plastic Hinge ◽  
Threshold Value ◽  
Maximum Strain ◽  
Strain Criterion ◽  
Pressurized Pipelines ◽  
Global Deformation ◽  
The Impact

A theoretical quasi-static analysis is proposed to predict the response and the onset of failure for pipelines. The maximum strain criterion, the effect of strain rate and an empirical formula for estimating the length of a plastic hinge are employed in the analysis. This theoretical study allows the local or denting deformation to continue during the global deformation phase. A good agreement has been achieved between the theoretical predictions and the corresponding experimental results for the threshold value of the impact energy and the maximum permanent transverse deflection for both unpressurized and pressurized pipelines. It transpires that both the maximum strain criterion and the empirical formula for the hinge length are applicable in the theoretical analysis. With a simple computer program, the theory can be used to predict the failure of pipelines. Discussions are made for the influence of internal pressure on the shape of the indentation and the threshold value of the impact energy.

Mechanical Properties of Metallic Thin Films: Tensile Tests vs. Indentation Tests

2003 ◽  
Vol 782 ◽  
Author(s):  
Nian Zhang ◽  
Changjin Xie ◽  
Wei Tong
Keyword(s):  
Thin Films ◽  
Test Data ◽  
Indentation Test ◽  
Tensile Tests ◽  
Equivalent Strain ◽  
Model Material ◽  
Polycrystalline Materials ◽  
Metallic Thin Films ◽  
Element Analysis ◽  
Indentation Tests

ABSTRACTThe existing interpretations of indentation test data (either theoretical or numerical approaches) have been largely based on isotropic plasticity models of polycrystalline materials while most of the metallic thin films widely used in many microelectronic and MEMS applications are strongly textured with a few grains or only a single grain running through the thickness of the films. The multicrystalline nature of the thin films on correlating their indentation and tensile properties is the focus of our investigation. Using multicrystalline aluminum and copper alloy thin sheets as model material systems, both tensile tests and indentation tests were performed and the testing results were compared based on a 3D crystal plasticity finite element analysis. The correlation between the indentation data and the tensile test data (at an effective or equivalent strain) is critically examined for these two multicrystalline materials.

Experimental Investigation of Charpy Impact Resistance in Rail Vehicle Steel Wheels

2006 ◽  
Author(s):  
A. Asadi Lari ◽  
S. H. Hashemi
Keyword(s):  
Fracture Energy ◽  
Test Data ◽  
Elastic Strain Energy ◽  
Charpy Impact ◽  
Fracture Initiation ◽  
Direct Result ◽  
Dynamic Crack ◽  
Rail Vehicle ◽  
The Impact ◽  
Total Fracture

In this research the Charpy impact properties of the two steel wheels of grade B2N and R7 were investigated. The dynamic toughness levels of test materials were measured experimentally according to the general recommendations of International Union of Railways (UIC) test standards. To do this, two sets of standard Charpy U-notch impact specimens were taken from the original rail vehicle steel wheels (made from B2N and R7) in their circumferential direction. As the conventional Charpy impact machine gives only one output (i.e., total fracture energy), an instrumented Charpy rig was used for conducting the impact experiments. This provided novel impact test data as well as full failure information (appeared for the first time in the literature for rail vehicle steel wheels). The obtained data included elastic strain energy, fracture initiation, and fracture propagation energy. All these parameters were calculated by double integration of load history captured by a high frequency digital oscilloscope during impact tests. The results showed that the impact toughness of both steel wheels was above the minimum toughness specified by the UIC leaflet. Detailed analysis of instrumented fracture test data showed that a significant portion of total measured Charpy energy (more than 75%) was consumed in fracture initiation and non-related fracture processes in each test material. This is a direct result of high strain-hardening capacity of B2N and R7 steel wheels and their characteristics, which allows the material to absorb high amounts of energy and to deform plastically before any fracture initiation. The total fracture energy of the R7 wheel steel was 160% higher than the B2N (21J against 13J), which was indicative of better dynamic crack resistance of R7 wheel material.

Dynamic Analysis of Large Specialty Glass Panels Under Ball Drop Impact — Numerical Modeling and Measurements

2012 ◽  
Author(s):  
Satish C. Chaparala ◽  
Praveen R. Samala ◽  
Joshua M. Jacobs ◽  
Jonathan D. Pesansky
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Energy ◽  
Consumer Electronics ◽  
Impact Loads ◽  
Cover Glass ◽  
Element Analysis ◽  
Glass Panels ◽  
Alumino Silicate ◽  
The Impact

Response of brittle plate-like structures to impact loads (suddenly applied loads) has been the subject of many research studies. Specifically, glass used in various household, consumer electronics applications can be subjected to different kinds of impact loads. An ion-exchanged alumino-silicate glass developed by Corning Incorporated, also called Corning® Gorilla® Glass is used as cover glass for flat-panel televisions. One of the reliability tests that may be required for this application is that a steel ball of certain diameter is dropped from certain height at different locations on the glass panel mounted onto a frame. The requirement is that the glass should survive 2 J of impact energy at the center of the glass and 0.5 J of impact energy at the edges. These reliability requirements could change depending on the application and the customer. In this study, finite element analysis is carried out to understand the impact response of such glass panels. Experiments are conducted using strain gauges to measure the panel response at the center of glass with impacts up to 3.3 J. Finite element analysis results are then validated by comparing the predicted strain response with those of measurements.

scholarly journals REDESIGN OF OUTER HOOD PANEL OF ESEMKA R2 CAR TO IMPROVE PEDESTRIAN PROTECTION USING FINITE ELEMENT MODELING

2016 ◽  
Vol 17 (2) ◽  
Author(s):  
Binyamin Binyamin
Keyword(s):  
Finite Element ◽  
Impact Energy ◽  
Traffic Accidents ◽  
Head Impact ◽  
Pedestrian Protection ◽  
Element Analysis ◽  
Impact Performance ◽  
Head Injury Criterion ◽  
Pedestrian Impact ◽  
The Impact

Traffic accidents are terrible scourge that occur in many countries, specially for developing countries where transportation affairs like tangled yarn. Besides functioning as an engine compartment cover, the hood of modern compact SUV can also help to manage the impact energy of a pedestrian’s head in a vehicle-pedestrian impact. This paper presents outer hood design of Esemka R2 that has a potential to improve hood’s ability and also to absorb the impact energy of a pedestrian’s head. The developed method for the design of an outer hood configuration aims to provide a robust design and homogeneous of Head Injury Criterion (HIC) for impact position at WAD 1000 and three different thicknesses (1.25 mm, 1.35 mm & 1.50 mm) of outer hood panel of Esemka R2 compact SUV, taking into consideration the limited space available for deformation. The non-linear Finite Element Analysis (FEA) software (Explicit Dynamics) was used in this research to simulate the testing procedurs of head impact for child pedestrian. The results show that the average of comparison dimensional of outer hood panel of Esemka R2 was 4.89 mm. The minimum of deformation space meet the requirement for HIC value which required obtaining robust and homogeneous head impact performance. Outer hood thickness and materials were identified as the factors to influence the stress and HIC value of the hood. By comparing all outer hood panels, aluminium alloy as the best selected material which has the lowest value is 32.78% for the pedestrian protection.

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