Metal forming （spinning）
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Currently, I am working on metal sheet metal forming. (Spinning) The sheet metal is in a normal state at low speeds, but at high speeds, 1. The sheet metal will float. There is another phenomenon, 2. When the spinning wheel touches the sheet material, it will take advantage of it as if there is a lot of kinetic energy. How to solve it
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I'm very sorry for not explaining this issue clearly.
Working condition: Blank and die are connected by *Constrained_EXTRA_NODES-SET. The blank is formed through multiple processing steps by wheel.There are some issues here.
SECTION A:
1、Normal circumstances:Rotating wheel speed 628 rad/min (100r/min), wheel feed rate 40mm//min. The following is the result of my simulation.
This is a normal phenomenon.
2、However, When I adjusted the speed of the die to 3140rad/min (500r/min), the wheel speed remains constant. After being in contact with the wheel for a period of time, the blank detached from contact with the spinning wheel and deformed itself.( Blank,-press down on his own) This is seriously divorced from the facts.
3、At that time, I thought the speed was given too fast, so I maintained a speed of 628 rad/min (100r/min), The wheel speed has been slowed down to 8mm/min. But there are still issues with situation 2, except that the amplitude of deformation of the sheet metal itself decreases.
4、At 500r/min, the blank showed outward drift, but the experimental blank did not show any outward drift. Why does this phenomenon occur ?
I want to know, Wheel, without putting pressure on Blank, What is the reason for Blank's own deformation. At present, I speculate on my own whether it is related to dynamic relaxation phenomenon.But this problem has been bothering me for a long time and has not been solved yet.
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All models are shell elements.
wheel modeled is rigid and no any anomalies
This is the material model.
The element type and elform and material model for the blank remain the same when the rotating wheel speed is 628 rad/min and when it is 3140 rad/min. Only the rotating speed curve (situation 2) or the X/Y feed curve has changed.
There are all keywords:
Energy issues：
situation 1（situation）：
There are internal energy, kinetic energy, and hourglass energy from matsum (blank).
Kinetic energy, and hourglass energy are all no more than 5%.
This is sliding energy from glstat.
But,I do not no how to judge.
Situation 2（3140rad/min）：
Perhaps due to the excessive rotational speed, the kinetic energy of the blank is too high, resulting in situation 3. Reduce the feed rate while keeping the rotational speed unchanged
Situation 3（100rad/min,feed rate 8mm/min）：
Simultaneously refining the grid.
This has not been calculated yet, as it has shown a tendency for the sheet metal to deform downwards on its own.
hourglass energy, and sliding energy :
I found that the slip energy in situation three is very large. Is this the reason and how to solve it？
I use ls-run2022 for the forming simulation.
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Hello Zhao,
Try to plot all internal, kinetic, hourglass, and sliding energies on the same graph as follows:
In this case, I am using fully integrated elements and so hourglass energy is zero. Also, without friction, sliding energy should be zero, or less than 10% of internal energy. In the case above, the sliding energy is zero.
Have you tried with shell elform=-16 instead of 2 for the blank?
You may want to increase the NIP to have more integration points through the thickness of the shell.
At last, if contact energy is large, this could be the problem. You can post-process the contact force in the RCFORC database and compare the different cases. Is the contact force much larger when the wheel speed is increased? If so, then the contact may be causing issues. Maybe the speed of the wheel is so fast that some nodes on the blank penetrate the wheel. The speed of the wheel may be too high and the penetration is not detected. Then, the contact force applies a force proportional to the penetration distance times contact stiffness (Force = K * Dpene). This could lead to large forces being generated. You can fix this problem by decreasing TSSFAC on *CONTROL_TIMESTEP to reduce the timestep so that the nodes in contact don't penetrate too much. Another option is to reduce the bucket sort frequency number. See the LS-DYNA User manual for more information on bucket sort frequency. The bucket sort setting will change based on SMP or MPP and SOFT=0, 1 or SOFT=2.
Note that changing the contact type and the SOFT option may solve this problem. Which contact are you using? Could you post a screenshot of your contact card with all options? The contact between the wheel and the blank.
Reno.
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Scenario 1: Is it due to the presence of rigid bodies that the model has a high kinetic energy
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I have been using Unit 2 and have not attempted full integration
There are my contact . I set it based on the dynamic spinning module
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But in the experiment, my spinning wheel speed was like this. How can I solve the generation gap between the experiment and simulation
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This is the contact stress between the spinning wheel and die and the sheet metal, The friction coefficient of 0.01 given by the wheel is used to simulate rolling friction
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