Hi，Bros，I want to simulate a compliant Mechanisms part using a dynamic step with ABS material in Explicit mode, and the results seem okay. My question is regarding this kind of simulation, what should I pay attention to? What are the differences between using Explicit and Implicit methods? And should I consider more about the material settings and etc…?
Check my recent tutorial about explicit dynamics: https://www.youtube.com/watch?v=-X0Shj7UXE0
Incrementation settings are crucial, I discussed them all in the video.
Thanks as always! bro
Very interesting analysis, @hua.
May I ask, why it is needed to run an explicit analysis for flexures simulations? A simple static analysis with non-linear behavior is not enough? Also, are you using which approach of design? I studied a little bit of FACT theory from Jonathan B. Hopkins and more recently the book by Larry Howell about compliant mechanisms. I look forward to using some of these theories in the future for something practical 
Hi,@ lucas_bueno
Actually, I’m not very proficient in simulation theory. The real appeal of a compliant mechanisms to me is that it allows for micrometer-level controllable displacement using rough 3D printed parts.Currently, I just need a simulation software that can accurately simulate the performance of flexures. I have tested explicit, implicit, and nonlinear static analyses under the same boundary conditions, and the results vary greatly. I am also trying to compare the actual printed parts with the simulation results. So, do you have any idea on this? 
Since the problem is not time-dependent, I would not use dynamic analysis (modal, implicit, or explicit). The main non-linearity is geometrical, so a simple *STATIC card with NLGEOM would be sufficient. Be aware that the solution depends on the “way” traveled to the solution, so smaller steps are needed to achieve a meaningful result.
Since your flexure is composed of 4 beams fixed in the outer structure guided by the inner structure while subjected to identical moments due to symmetry, I think it would be nice to use the formulation from section 5.3 of Larry Howell’s book so that your model becomes pseudo-rigid links made stiff by torsional springs:
I would also refine your mesh in the flexure (it is very coarse at the moment).
You could compare analytical, simulation by FEM, and experiment. However, keep in mind that 3D-printed models are inherently anisotropic.
Hi, lucas_bueno ,Thank you for your guidance, and the information you’ve provided is great for delving deeper into the theory. What I ultimately want from the simulation is to input a displacement into a compliant component and determine the resulting displacement at the other end. It’s like the part shown in this video：https://www.youtube.com/watch?v=YbWY3aKm98c ， So these formulas may not directly provide the answer right now I think.
What an interesting research area.!!.
Some of these devices show highly non-linear behavior with sudden zero stiffness or stable post buckling configurations. Those paths should be better inspected imposing displacements than loads.
Yes, I agree. But it would be a nice approach to first investigate the analytical behavior one would expect and then proceed to a more complex analysis. The book also has imposed displacement formulations. Since you know more or less the force applied by torque transfer, I would use forces first because the formulations are inexpensive to calculate analytically. But of course, this is a design choice of yours.
