This post discusses a solution for modeling a traveling load on Maplesim's Flexible Beam component and provides an example of a bouncing load.

The idea for the above example came from an attempt to reproduce a model of a mass sliding on a beam from MapleSim's model gallery. However, reproducing it using contact components in combination with the Flexible Beam component turned out to be not straightforward, and this will be discussed in the following.

To simulate a traveling load on the Flexible Beam component, one could apply forces at discrete locations for a certain duration. However, the fidelity of this approach is limited by the number of discrete locations, which must be defined using the Flexible Beam Frame component, as well as the way in which the forces are activated.

One potential solution to address the issue of temporal activation of forces is to attach contact elements (such as Rectangle components) at distinct locations along the beam, which are defined by Flexible Beam Frame components, and make contact using a spherical or toroidal contact element. However, this approach also introduces two new problems:

• An additional bending moment is generated when the load is not applied at the center of the contact element's attachment point, the Flexible Beam Frame component. Depending on the length of the contact element, deformations caused by this moment can be greater than the deformation caused by the force itself when the force is applied at the ends of the contact element. Overall, this unwanted moment makes the simulation unrealistic and must be avoided.
• When the beam bends, a gap (see below) or an overlap is created between adjacent Rectangle components. If there is a gap, the object exerting a force on the beam can fall through it. Overlaps can create differences in dynamic behavior when the radius of curvature of the beam is on the opposite side of the point of contact.

To avoid these problems, the solution presented here uses an intermediate kinematic chain (encircled in yellow below) that redistributes the contact force on the Rectangle component on two support points (ports to attach Flexible Beam Frame components) in a linear fashion.

To address gaps, the contact element (Rectangle) attached to the kinematic chain has the same width as the chain and connects to the adjacent contact elements via multibody frames. In the image below, 10 contact elements are laid on top of a single Flexible Beam component, like a belt made out of tiles. The belt has to be pinned to the flexible beam at one location (highlighted in yellow). The location of this fixed point determines how the flexible beam is loaded by tangential contact forces (friction forces) and should be selected carefully.

Some observations on the attached model:

• Low damping and high initial potential energy of the ball can result in a failed simulation (due to constraint projection failure). Increasing the number of elastic coordinates has a similar effect. Constraint projection can be turned off in the simulation settings to continue simulation.
• The bouncing ball excites several eigenmodes at once, causing the beam to wiggle chaotically in combination with the varying bouncing frequency of the ball. A similar looking effect can also be achieved with special initial conditions, as demonstrated with Maple in this excellent post on Euler beams and partial differential equations.
• Repeated simulations with low damping lead to different results (an indication of chaotic behavior; see three successive simulations below (gold) compared to a saved solution(red)). The moment in the animation when the ball travels backward represents a metastable equilibrium point of the simulation. This makes predictions beyond this point difficult, as the behavior of the system is highly dependent on the model parameters. Whether the reversal is a simulation artifact or can happen in reality remains to be seen. Overall, this example could evolve into a nice experimental fun project for students.

• Setting the gravitational constant for Mars, everything is different. I could not reproduce the fun factor on Earth. A reason more to stay ,-)

Ball_bouncing_on_a_flexible_beam.msim

I was not able to apply ICs (initial conditions) using the advanced parameter settings of the flexible beam component in the attached file. My intention is to have a beam moving at t=0s (velocity of end frame <> 0). The computed initial values for the elastic coordinates (see output console for the disabled component below encircled in red) indicate that the flexible beam has no kinetic energy at t=0s.

A workaround is to attach a rigid body to the end frame and apply the ICs to the body. (Inertia and mass of the rigid body can be set to zero.)

How to apply initial conditions to the disabled component so that it moves as the workaround?

Imposing_IC_v.msim

I cannot. If I right click on the warning I get only a copy option

Double_Pendulum_warning.msim

I am now using maplesim to do research on railway vehicles. When I replace the rails with flexible beams in maplesim, I try to connect the rails and two sleepers with moving pairs, and I find that there are over-constraint problems. How to replace the rails with flexible bodies? Are the rails connected with multiple sleepers?

I hope you can give me some advice, thank you very much.

designing  a block definition diagram for a smart pet feeder 

Hey Guys in the attached file below, how can i create a spatial motion (3 traditional + (1 rotational) )? i keep getting errors when i use both for my Rigid body frame. I just have to activate one of the Translational or Rotational block at same time , is there any solution here

Spatial_Motion2.msim

Hey Guys . is it possible to import a Simulink block into maplesim . can some one explain the process . i already found something called BlockImporter Add-in. but it's some old maple addins and it's not support Windows 10

Bonjour, petite question simple que je me pose la MapleSim permet de tout réaliser ?

Hello, 

I am new to modelica modeling in Maplesim, how do I add ports to the custom component created by Modelica Custom Component in MapleSim?

thanks. 

Hello,

  2022 was a wonderful year of progress in using Maple/MapleSim for almost everything my mathematical world.     

I just wanted to wish all the Maplesoft user community a very productive and Happy New Year for 2023.   I look forward to continue to find great nuggets of capability and insider techniques for using Maple in my endeavors.

Kindest Regards to ALL.
Happy New Year - 2023.
Bill

I remember a section “Tell us what we can do better” at the bottom of online help pages. I used this whenever I came across a potential error worth investigating.

Has this section disappeared (I hope not) or do I have a browser issue?

Hello everyone,

I am first time using the Flexble Beam block, and I tried simple cantilever beam with mass at the free end. Deflection is not as I expected (comparing to my hand calculations). I have tried also to use Force instead of mass (with a same load quantity), but nothing changed. Is there something that I might be missing? Expected deflection of a free end is 15 mm (I have obtained 2,8 mm in Maplesim).

Thanks!

For the simulation of a microcontroller I am looking for discrete components like AD and DA converters, filters, differentiators, integrators.

The plant to be controlled is built with components from the MapleSim 2022 component library.

If there are no libraries that are compatible with the current version of MapelSim, I wonder if there is something that could be customized.

Any insights on the subject are welcome.

A failing slinky is another intriguing physics phenome that can be easily reproduced with MapleSim.

The bottom of a vertically suspended slinky does not move when the top is released until the slinky is fully collapsed.

To model this realistically in MapleSim, it is necessary to

• Establish a stretched equilibrium state at the start of the fall
• Avoid penetration of windings when windings collapse (i.e. get into contact)

The equilibrium state is achieved with the snapshot option. Penetration is avoided with the Elasto Gap component. Details can be found in the attached model.

A good overview of “Slinky research” is given here. The paper provides a continuous description of the collapse process (using an inhomogenous wave equation combined with contact modeling!!!) and introduces a finite time for the collapse of all windings. Results for a slinky are presented that collapses after 0.27s. The attached model has sufficient fidelity to collapse at the same time.

Real Slinkies also feature a torsional wave that precedes the compression wave and disturbs an ideal collapse. This can be seen on slowmo footage and advanced computer models. With a torsion spring constant at hand (are there formulas for coil springs?), it could also be modeled with MapleSim.

Falling_slinky.msim

Maple offers the dimension “lenght” whereas MapleSim offers two types.

What is the difference between the two types length and distance?

Can they always be used interchangeably?