To analyse and compare results for different types of materials/material properties with the same boundary conditions.

Objective: To analyse and compare results for different types of materials/material properties with the same boundary conditions.

#The results are discussed in ppt attched

Case 1:Law 2-M2_Plas_Johns_Zeril – Elasto-plastic:

In this case the material is considered to be an elasto-plastic with input parameters given.On top of that Fail_Johnson card is added which helps with capturing the stresses under compression.The input parameters such as eps_p_max, sigma_max0, a, b, n are already filled in.The task at hand is to input element properties for the 2d Shell elements.The recommended inputs for a non-linear analysis were added as follows:

Case 2:Law 2 with Fail_Johnson and Crack visualisation:

In this case a few parameters are added to the already defined case 1 to visualize cracking or breaking down of elements with the help of 'Ixfem' option in Fail_johnson failure model card.As asked, the necessary changes were made in the parameters as follows:

Case 3: Law 2 WITHOUT fail_johnson card:

In this case the material model is same as in case 1 -Law 2 Elasto plastic but the failure model card is removed to look for any difference in the results.Hence, the Plas_Johnson card was deleted and the simulation was done.As we know that law2 material model is not capable of simulation compression under forces with realistic results, Plas_johnson card is a recommended addition.

Case 4:Law2 with infinite eps_p_max value:

In this case the Eps_p_max value which defines the maximum permited plastic strain is changed to 0 which inputs a value of 10^30 as default.This makes the material to behave like ideal elasto platic such that strain is computed but not failure due to platic deformation beyond limit is experienced.

Case 5:Law1- Elastic material:

Here, the maerial is modelled as an ideal elastic which linearly follows hooks law and is in elastic region throughout any stress no matter the magnitude.The basic E, Nu, Rho parameters are input and the analysis is done.Here no plasticity is expected from the component material.

Case 6:Law 27- Plas_Brit material:

In this case the material model is Plas_brit which is an elasto-plastic material model eith additional parameters to define brittle nature of the material such as eps_t1 , t2 eps_f1 , f2, Eps_m1 , m2 and dmax1 , 2 which are tensile failure strain, maximum tensile failure, tensile strain at element deletion and maximum tensile damage limit in two directions. To start with Law27 is nothing but Law2 with additional parameters hence a much detailed analysis can be done.

Shell element properties were updated in this case too to recommended.

Case 7:Law36- Plas_tab material:

In this material model the input parameters previously discussed eps_p , eps_m and eps_t in a single direction are defined.The important feature of the model is user can input a stress v/s strain plot as a curve and call it in the card from which strain rate parameter is computed.Also, scaling factor, hardeining coefficient etc can also be added to give further details for better analysis.The necessary inputs were gathered from video lecture material 6 and 7 and were added to the model.

Shell element properties were edited to recommended values again.

Conclusion:

After studying the results and energy plots for each case (in ppt attached)and comparing them, following conclusions were made:

The material in question is Aluminium alloy case 1, case 6 and with proper inputs case 7 will give out realistic results. Law 27-Plas_brit material model is the best option with given inputs with more detailed results than Law 2-Elasto plastic with Fail_Johnson card. At last Plas_tab material model being sensitive to its inputs(Stress v/s strain curve) , Plastic strain parameters, could be another option but needs accurate data preferably from physical testing.

PPT :

https://drive.google.com/open?id=11_k8zTLVFByOw_SK0AjE-xMofk-FYxvI

Folder with all the output files and plots:

https://drive.google.com/open?id=1PK5jeA5-JWSmN2BA_THJuOJCT3fwVJ1T