Wyniki wyszukiwania - BazTech

1

Damage evolution of vehicle motor rotor under single working condition based on GTN model

He Liange, Yuan Zhou, Shi Wenjun, Qu Xiang

Journal of Theoretical and Applied Mechanics

|

2022

|

Vol. 60 nr 4

561--577

EN

To study evolution of the void in the material of a motor rotor under different working conditions from a mesoscopic perspective, damage analysis of the rotor has been carried out based on thermal-mechanical coupling theory. According to the test methods of GB/T 228.1-2010 Part 1 and GB/T 228.2-2015 Part 2, tensile tests were conducted on rotor ma- terials at different temperatures to obtain basic mechanical property parameters, and pa- rameters of the fine-scale damage model at different temperatures were fitted by combining orthogonal tests and a finite element inverse calibration method. Then, the accurate tem- perature distribution law of the motor rotor was obtained through CFD calculation. Based on the material parameters and temperature data, the void evolution of the rotor material under thermal-mechanical load was studied by using the finite element method. The results show that: under the rated conditions, the stress concentration of the rotor is mainly ap- peared in the joint with the shaft, the maximum stress was 304.1MPa, which did not reach the yield limit of the material. No plastic deformation occurred, so the volume fraction of voids inside the rotor material did not change still for the initial pore volume fraction of 2.5 · 10−3. In the peak condition, the stress concentration appeared in the rotor plate across the joint of the magnetic bridge and pole shoe with a maximum stress of 354.4MPa and a small plastic strain of 1.133 ·10−3. The pore volume fraction increased to 2.503 ·10−3, where the initial pore growth of 2.150 · 10−6 and the secondary pore nucleation of 2.079 · 10−12.

2

Experimental determination and numerical simulation of material and damage behaviour of 3D printed polyamide 12 under quasi-static loading

Schob D., Roszak R., Sagradov I., Sparr H., Ziegenhorn M., Kupsch A., Léonard F., Müller B. R., Bruno G.

Archives of Mechanics

|

2019

|

Vol. 71, nr 4-5

507--526

EN

In order to characterise the material and damage behaviour of additively manufactured polyamide 12 (PA12) under quasi-static load and to implement it in a numerical model, experiments under quasi-static load as well as microstructural investigations were carried out. Selective laser sintering (SLS) was used as the manufacturing process. For the classification of the material behaviour, quasi-static cyclic tests with holding times as well as tensile tests were performed. X-ray refraction and computed tomography (CT) were used to investigate the damage behaviour. The Chaboche model, which has already been applied for metallic materials under thermomechanical loading, served as the basis for the selection of the numerical material model. The same procedure was used for the selection of the damage model, where the Gurson–Tvergaard–Needleman (GTN) model was chosen, which was already used for porous metallic materials. The Chaboche model shows very good agreement with experimental results. Furthermore, the coupling with the GTN model allows a very good modelling of the damage behaviour. Finally, it could be shown that the selected models are suitable to simulate the material and damage behaviour of 3D printed PA12.

3

Study of the influence of cold working on mechanical behavior and ductile fracture of 5754 aluminum alloy: experimental and numerical simulations

Taktak W., Taktak R., Haddar N., Elleuch R.

Journal of Theoretical and Applied Mechanics

|

2017

|

Vol. 55 nr 3

923—935

EN

The ductile damage of automotive aluminum sheet alloy AA5754-H111 is investigated by experiments and numerical simulation using the Gurson-Tvergaard-Needleman (GTN) model. The GTN parameters were determined by a uni-axial tensile test and the inverse finite element method. The same parameters were employed to provide the ductile damage behavior of central cracked panel (CCP) specimens. A good prediction can be established among the numerical simulation and experimental data in from of the force opening displacement. As an application, the identified GTN model is used to predict the influence of cold working on deformation and ductile damage. The numerical simulation results obtained are assimilated with experimental data.

4

Crack initiation analysis in structural steel by application of micromechanical approach.

Rakin M., Cvijovic Z., Grabulov V., Sedmak A.

Inżynieria Materiałowa

|

2001

|

R. XXII, nr 5

741-744

EN

Crack initiation in a structural steel, following void nucleation, growth and coalescence, has been analysed. The so-called coupled approach of micromechanical analysis of material damage has been applied. Such an approach is based on experimental testing of both precracked and non-precracked specimens, finite element (FE) calculations and metallurgical analysis. Numerical analyses of ductile-fracture initiation in ferritic steel were carried out through participation in the round robin project organised by European Structural Integrity Society (ESIS) [1]. Smooth round specimens and CT specimens were tested. Critical values of micromechanical damage parameters determined for smooth specimen were used to predict the onset of crack initiation in CT specimen and subsequently to model its stable growth. The analysis of the first phase of ductile fracture, void nucleation, was carried out by applying quantitative metallographic analysis of size and number of non-metallic inclusions. Based on this analysis, initial void volume fraction, used as input information in the large strain (updated Lagrangian) FE calculation, was determined. The results obtained suggest that the critical values of micromechanical parameters according to GTN model may be used for approximate prediction of ductile fracture initiation on CT specimen for tested steel.