Relationship Between Charpy V-Notch Impact Value and Fracture Mechanics Toughness: Added Value of Finite Element Analysis and Instrumented Impact Tests

2011 ◽  
Author(s):  
Philippe Thibaux ◽  
Filip Van den Abeele ◽  
Philippe Burlot
Keyword(s):  
Finite Element ◽  
Master Curve ◽  
Impact Test ◽  
Crack Arrest ◽  
Smooth Transition ◽  
Unstable Crack ◽  
Impact Tests ◽  
The Difference ◽  
Energy Dissipated ◽  
The Impact

Each structure is designed with resistance versus the fracture, which requires the knowledge of the fracture resistance of the material. If no fracture mechanics data of the material is available, a KJC can be inferred from the master curve approach. The master curve approach relates a fracture toughness of 100 MPAm1/2 to the impact transition temperature T27J with a shift of 18°C. Although this relationship was successfully applied to a large number of experiments, some steels deviate significantly from the previous relationship, which can even lead to non-conservative design. In the present paper, instrumented impact tests (Charpy V-Notch CVN) and compact tensile (CT) tests were performed on two materials, one thermomechanically (TM-) rolled and one normalized steel. The difference between T0 and T27J was found to be different for these materials. Furthermore, the normalized steel exhibits a smooth transition from brittle to ductile behaviour, while the TM-rolled material shows a very steep transition. Extra information is gained by combining the instrumentation of the impact test and the finite element simulations of both the CT and impact tests. From the instrumented tests, it is also possible to determine the load at unstable crack propagation, the amount of energy dissipated at that moment, the load at crack arrest and the energy dissipated after crack arrest. From the finite element simulation, one learns about the constraints ahead of the crack tip for both configurations. The investigation teaches us that the smooth transition of the normalized material is related to a high energy dissipated after crack arrest, while the TM-rolled material has a much lower crack arrest load. The difference between T0 and T27J is then discussed by decomposing the total energy in the impact test between crack initiation, propagation and arrest. It is compared with KJC, which determines the toughness at unstable crack propagation, by reviewing the literature and local stress states computed from finite element.

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.

EFFECT OF RELATIVE DENSITY AND VELOCITY TOWARDS DYNAMIC RESPONSE OF METAL FOAM

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Mohd Azman Y. ◽  
Juri S. ◽  
Hazran H. ◽  
NorHafiez M. N. ◽  
Dong R.
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Theoretical Prediction ◽  
Relative Density ◽  
Impact Velocity ◽  
Impact Test ◽  
Metal Foam ◽  
Element Analysis ◽  
Static Tests ◽  
The Impact

Dynamic response of ALPORAS aluminium foam has been investigated experimentally and numerically. The dynamic response is quantified by the force produced as the foam deforms as a function of time. Quasi-static tests are conducted to determine the quasi-static properties of the foam. In the impact test, the aluminium foams are fired towards a rigid load-cell and the force signals developed are recorded. Experimental dynamic stress is also compared with theoretical prediction using existing theory. Finite element model is constructed using LS-DYNA to simulate the impact test. Results from the experiment, finite element analysis and theoretical prediction are in acceptable agreement. Finally, parametric studies have been conducted using the verified model to investigate the effect of impact velocity and relative density towards the dynamic response of the foam projectile. It is found that the dynamic response of the foam is more sensitive towards impact velocity as compare with the foam relative density.

Ductile Fracture Characterization of an X70 Steel: Re-Interpretation of Classical Tests Using the Finite Element Technique

2008 ◽  
Author(s):  
Philippe Thibaux ◽  
Se´bastien Mu¨ller ◽  
Benoit Tanguy ◽  
Filip Van Den Abeele
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Pipeline Steel ◽  
Damage Model ◽  
Base Material ◽  
Steel Production ◽  
Crack Arrest ◽  
Finite Element Simulations ◽  
Charpy Test ◽  
The Impact

The crack arrest capacity of a linepipe is one of the most important material parameter for such components. In current design codes, it is expressed as the energy absorbed by a CVN impact test. This prescribed impact energy for a given pipeline is typically between 50 and 120J, depending on the grade of the material, the pressure and the dimensions of the pipe. The continuous improvement of steel production has lead to the situation that the impact values achieved in standard pipeline steel production are much larger than 200J for the base material. The question of the significance of these high impact energies can be raised, particularly considering that no correlation has been found between CVN values and crack arrest properties of very high strength materials (X100–X120). In this investigation, instrumented Charpy tests and notched tensile tests were performed on an X70 material. The same tests were also simulated using the finite element method and the Gurson-Tvergaard-Needleman damage model. The combination of supplementary experimental information coming from the instrumentation of the Charpy test and finite element simulations delivers a different insight about the test. It is observed that the crack does not break the sample in 2 parts in ductile mode. After 6–7mm of propagation, the crack deviates and stops. The propagation stops when the crack meets the part of the sample becoming wider due to bending. Finite element simulations proved that it results in a quasi constant force during a displacement of the hammer of almost 10mm. The consequence is that more than 25% of the energy is dissipated in a different fracture mode at the end of the test. Finite element simulations proved also that damage is already occurring at the maximum of the load, but that damage has almost no influence on the load for two-thirds of the displacement at the maximum. In the case of the investigated steel, it means that more than 27J, as often mentioned in standards for avoidance of brittle failure, are dissipated by plastic bending before the initiation of the crack. From the findings of this study, one can conclude that the results of the Charpy test are very sensitive to crack initiation and that only a limited part of the test is meaningful to describe crack propagation. Therefore, it is questionable if the Charpy test is adapted to predict the crack arrest capacity of steels with high crack initiation energy.

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.

Impact Behaviour of Composite Materials by Using Low and High Speed Impact Tests

2012 ◽  
Vol 445 ◽  
pp. 189-194
Author(s):  
Enver Bulent Yalcin ◽  
Volkan Gunay ◽  
Muzeyyen Marsoglu
Keyword(s):  
Composite Materials ◽  
High Speed ◽  
Impact Test ◽  
Woven Fabrics ◽  
Impact Behaviour ◽  
High Speed Impact ◽  
Impact Tests ◽  
Data Acquisition Software ◽  
Damage Process ◽  
The Impact

The study presents the need for instrumented testing to optimizing materials against impact forces. The objective of the study is how the impact behaviour of composite materials is investigated by slow and high speed impact tests. Instron Dynatup 9250HV and Instron Dynatup 8150 Impact test machines (Fig.1.) are used which are located in TUBITAK-MRC, Materials Institute , Impact Test Laboratory". The damage process in composite materials under low and high velocity impact loading and the impact energy-displacement properties of the composite materials were investigated. Composite samples were produced by woven fabrics. The results are given as graphs and tables. The Impulse Data Acquisition software is used to send the data to computer.

The Study on Medium Filling Scheme of LNG Tank Container Impact Testing Based on ANSYS

2014 ◽  
Vol 912-914 ◽  
pp. 869-872
Author(s):  
Jing Cao ◽  
Mei Han ◽  
Jing Yu Qi
Keyword(s):  
Finite Element ◽  
Impact Test ◽  
Test Procedure ◽  
Impact Testing ◽  
Finite Element Calculation ◽  
Element Calculation ◽  
Dangerous Goods ◽  
Test Conditions ◽  
Lng Tank ◽  
The Impact

Proposal the medium filling scheme of LNG tank container impact testing that filling the tank with water which mass is equal to dangerous goods, since the medium filling scheme before is difficult and loss, by finite element calculation with ANSY to the stress of LNG tank framework in the actual conditions and test conditions. Studies show that the two conditions of the tank is similar, test conditions can simulate the actual filling conditions. Applying this conclusion to the impact test, which can greatly simplify the test procedure and reduce the difficulty of the test, the test can be enhanced operability and economy.

scholarly journals Analysis of Impact Characteristics and Detection of Internal Defects for Unidirectional Carbon Composites with Respect to Fiber Orientation

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 203
Author(s):  
Sun-ho Go ◽  
Alexandre Tugirumubano ◽  
Hong-gun Kim
Keyword(s):  
Carbon Fiber ◽  
Impact Test ◽  
Carbon Fiber Composites ◽  
Internal Defects ◽  
Impact Tests ◽  
Drop Weight ◽  
Weight Impact ◽  
Fibers Orientation ◽  
Lock In ◽  
The Impact

With the increasing use of carbon fiber reinforced plastics in various fields, carbon fiber composites based on prepregs have attracted attention in industries and academia research. However, prepreg manufacturing processes are costly, and the strength of structures varies depending on the orientation and defects (pores and delamination). For the non-contact evaluation of internal defects, the lock-in infrared thermography was proposed to investigate the defects in the composites subjected to the compression after impact test (CAI). The drop-weight impact test was conducted to study the impact behavior of the composites according to fibers orientation for composite fabricated using unidirectional (UD) carbon fiber prepregs. Using CAI tests, the residual compressive strengths were determined, and the damage modes were detected using a thermal camera. The results of the drop weight impact tests showed that the specimen laminated at 0° suffered the largest damage because of susceptibility of the resin to impact. The specimens with 0°/90° and +45°/−45° fibers orientation exhibited more than 90% of the impact energy absorption and good impact resistance. Furthermore, the specimens that underwent the impact tests were subjected to compressive test simultaneously with the lock-in thermography defects detection. The results showed that internal delamination, fibers splitting, and broken fibers occurred. The temperature differences in the residual compression tests were not significant.

Study of the Impact Properties of Steel 25Mn

2011 ◽  
Vol 704-705 ◽  
pp. 1035-1040
Author(s):  
Da Yong You
Keyword(s):  
Crack Propagation ◽  
Impact Test ◽  
Charpy Impact ◽  
Hardness Test ◽  
Fracture Morphology ◽  
Charpy Impact Test ◽  
Deformation And Fracture ◽  
The Difference ◽  
Hot Rolled ◽  
The Impact

The Charpy impact test、hardness test、microstructure and morphology analysis of impact fracture by SEM were introduced to research the difference of impact toughness on 25Mn, which were in the station of hot-rolled、normalized and quenched & tempered. The resulted showed that the changes of load、deformation and energy exhaust in difference stage of deformation and fracture could be gained by Charpy impact test. 25Mn in quenched & tempered has more deformation resistance and deformation property than which in other stations. The total impact values was 6J higher than which in normalized in average, however, the crack propagation values was 16.78J higher in average. Ductile-brittle property of the material can be estimated by the analysis of crack formation values、crack propagation values and fracture morphology on samples.

A study of temperature rise in oil due to compression

1998 ◽  
Vol 212 (4) ◽  
pp. 291-299 ◽  
Author(s):  
K Imado ◽  
Y Kido ◽  
H Miyagawa ◽  
F Hirano
Keyword(s):  
Temperature Rise ◽  
Impact Test ◽  
Volumetric Strain ◽  
Viscosity Coefficient ◽  
Maximum Temperature ◽  
Compression Tests ◽  
Maximum Acceleration ◽  
Impact Tests ◽  
Higher Temperature ◽  
The Impact

Temperature rises of various oils were measured in both impact tests and quasi-adiabatic compression tests. A steel ball impacted against an oiled sapphire glass in the impact test. It was found that the maximum temperature rise was 45 °C in impact tests. A close relationship between temperature rise and α amax was found for oils of relatively low viscosity, where α was the pressure-viscosity coefficient and amax was the maximum acceleration of the hammer during impact; namely, the temperature increased with each increase in the product of the contact force and the pressure-viscosity coefficient. In the compression tests, the temperature increased almost linearly with increase in the volumetric strain regardless of the type of oil. The order of the temperature rise for the corresponding oil in each experiment was reversed; i.e. a higher temperature increase was observed for an oil of smaller pressure-viscosity coefficient in the compression test. On the contrary, a higher temperature rise was noted in the case of a larger pressure-viscosity coefficient in the impact test. As far as the temperature rise is concerned for entrapped oil in the impact tests, there exists an optimum combination of viscosity and pressure-viscosity coefficient.

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