Assignment 5

Assignment5

Aim: Meshing and simulation results using hyper mesh, hyper crash radioss.

Objective: to generate meshing of bumper system with mesh size=6mm, and checking simulation results of crush tube file chnging the types of contact interfaces as type 7, type 11,also changes in some properties, and adding& removing of notches, removing of boundary condition. plotting the results of energies, rwall forces,contact forces.

Methodology: Bumper system

• Open bumper system in hyper mesh.
• Check geometry, trim middle free surfs, attached surfs to surfs with replace point and toggle edges.
• Auto mesh-select displayed surfs-mesh size =6mm -mesh –return.
• Check quality index.

Crush tube file:

Case 1

• Open hyper mesh and import crush_ tube_0000.rad file and run as it is.
• Open h3d file in hyper view, contour-contact force and von mises stress.

We can see max contact forces are 7.77N and von mises stress 6.9E-01.

• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part.

In 1^st case IE starts from zero, and higher 42kj at approximate 26ms.KE is starts from slightly below 45000 as there is -3.8% of energy error and goes on decreasing up to 26ms and after that it is constant. As graph shows there is some contact energy increases after approximate 23ms.hour glass energy is zero, and total energy is start from same point as kinetic energy and meet the point at IE is higher.

The pick of rigid wall force is higher at 26.5ms the crumbling of the tube which consumes energy and hence less force is generated on wall. The force as velocity tries to push upper part towards the rigid wall and tries to crush the tube. Since after picking the26.5ms no further transmission of force.

Case2:

• Open hyper crash and import crush_ tube_0000.rad file.
• Browser_ contact interfaces _double click o self contact _change inacti=6and run the model.
• Open h3d file in hyper view, contour-contact force and von mises stress.

Von mises stress for both 1s and 2^nd cases are same.

As compare to the 1^st case the max contact force is 7.7N and in 2^nd case max contact force is 2.244N, there because we change inacti=0 to inacti=6 therefore initial penetration is removed and contact forces reduces.

• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part.

In 2^nd case IE, KE, TE, hourglass energy, contact energy result is same as in 1^st case

In this case we see the pick of the valley is slightly moved towards the 25ms, and the plot is same as in 1^st case.

Case 3

• Open hyper crash and import crush_ tube_0000.rad file from 2^nd
• Create contact type 11.

Change the property of type 7 as shown in video

Istf=4 Igap=2

Idel=2 Stmin=1

Gapmin=0.5 Inacti=6

Fric=0.2 Ifom=2

• And also create type 11

Istf=4 Igap=1000

Idel=0 Stmin=1

Gapmin=0.45 Inacti=6

Fric=0.25 Ifom=0

• Open h3d file in hyper view, contour-contact force and von mises stress.

We can see in this case stresses somewhat reduced as compared to 1^st and 2^nd case. Contact force is increase in this case because gapmin factor changes.

• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part.

In this case IE reduces as compared to above 2 cases; some change in pick value27ms to 25ms and contact energy is increases slightly.

the pick of the rwall force move towards the 25ms and the force is increases 1629.4N.

Case4:

• Open hyper crash and import crush_ tube_0000.rad file from 3^rd
• Remove all notches using align node option
• Remove boundary condition on rigid body node then run
• Open h3d file in hyper view, contour-contact force and von mises stress.

In this stress is less because of removal of notches.

As change in notches and boundary condition we see the result.

• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part

The plots are Similar to above cases only the difference is the picks of slope move slightly after 25 ms.

here we see the highest pick point of the rwall force is at 1354.50.

Case5:

• Open hyper crash and import crush_ tube_0000.rad file from 4^th
• Create a new notch in the middle, select the whole section using move node option
• Remove boundary condition on rigid body node as in 4^th case then run.
• And input parameters are kept same.
• Open h3d file in hyper view, contour-contact force and von mises stress.

We can see von mises stress is less as compared to all above 4 cases.

• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part.

The plots are Similar to above cases only the difference is the picks of slope move slightly after 25 ms.

here we see the highest pick point of the rwall force is at 1487.70.

Case6:

• Open hyper crash and import crush_ tube_0000.rad file from 4^th
• Create a new notch with node only from opposing two faces, and run.

Here we have create notch on opposite faces of tube using translate option. The notches are randomly placed at middle of the tube.

• Open h3d file in hyper view, contour-contact force and von mises stress
• Open T01 file in hyper view, plot internal energy, Rwall forces, TH/part.

Because of the only two opposing notches IE is lowers, and contact energy is slightly increase.

here we see the highest pick point of the rwall force is at 1698.07 which highest in all cases.

Comparison of all cases

Sr. no.	Simulation time	Energy error	No cycles	Contact forces	Internal energy	Rwall forces
Case1	29.98	-3.8%	83691	2.244E+01	0.4201E+05	1340.6512451171875
Case 2	29.98	-3.8%	83691	2.244E+01	0.4201E+05	1340.6590576171875
Case 3	29.98	-5.7%	85593	2.811E+02	0.4099E+05	1629.4044189453125
Case4	29.98	-6.2%	74854	2.550E+02	0.4082E+05	1354.500732421875
Case5	29.99	-6.4%	73247	3.343E+02	0.4059E+05	1487.7066650390625
Case6	29.99	-6.0%	74328	3.854E+02	0.4052E+05	1698.0712890625

conclusion: when input of all type 7 and type 11 with recommended parameters and oppossing notches give best result as comparing with the all result becuase there is less internal energy consumed.but has disadvantage as the forces requied more and energy error is also obtain.

all simulation files and bumper system file is attached.