SDNews : July 2024
??[Expertise] Model verification for quality assessment – Mesh level
Model verification can be a tedious task.
Delving into the nitty-gritty details of finite element models of ever-growing size and complexity is seldom valued.
This is especially true when the simulation already runs.
It is, however, the first step to avoid the so-called Garbage In/Garbage Out shortfalls.
?A first post on model verification has been published on our website
It focuses on mesh-related verifications:
?? Why can “too distorted” elements lead to negative Jacobians and numerical issues?
?? How to efficiently detect and address distorted elements?
?? Is mesh convergence well controlled when using first order elements or reduced integration techniques?
???[Conference] EuroBrake 2024
#EuroBrake took place in Mainz and SDTools was attending with Guilllaume Vermot des Roches. No presentation for us this year, but we are still very active in brake NVH applications, so we were very happy to get in touch with all other attendees !
Our recent work focuses on a fast method where an HBV (Harmonic Balanced Vector) signal model is estimated using demodulation. This allows tracking of instant frequency, damping and spatial shapes from transient squeal signals. This method can be used to analyze very long experimental measurements and simulation results.
The attached movie illustrates this technique : it is applied to track a squeal response obtained from a non-linear time simulation on a simplified brake model.? The pressure field first harmonic is displayed over time to illustrate its evolution as amplitude grows.
We will submit communications soon on this technique, applied on both test measurements and simulations – stay tuned!
Coming back from an insightful #Eurobrake event in Mainz, it is time to gather all notes and discussions into valuable takeaways and thoughts. ??Read full Guillaume Vermot des Roches' feedback post...
???[Software] Experimental Modal Analysis using SDT dedicated GUI (dock ID)
SDT provides advanced solutions for Experimental Modal Analysis. They are integrated in the dock Id providing an interactive interface to perform this task:
?? Define pole/residue model options
?? Initialize poles (mode frequency and damping)
?? Estimate residues (shapes)
?? Check identification quality
? Animate mode shapes
领英推荐
?? Optimize modes (poles + residues)
?? Generate automated report
The video demonstrates its use for standard cases.
Many refinements can be needed in the process.
The tool is thus meant to be versatile in the options, visualization choices, and tuning for expert users if needed.
It retains a default configuration that should suit most needs, devised from our numerous application cases throughout the years.
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Stay-tuned for more theoretical explanations in a newsletter !
??[Expertise] Coupling for mechanical assemblies
How do you handle simplified connections in a Finite Element Model with control on accuracy?
?Modern simulation capabilities allow considering very large finite element models, including mechanical assemblies. They require interaction models between components, that can be seen as interface connections (junctions, fasteners, contact support…).
? High fidelity modelling would consider all 3D parts to be meshed, with contact/friction interactions in between. But fully detailed interface connections are not always suitable because it takes time to model, and we need to control model size and convergence
?How to perform connection simplifications, while complying to simulation objectives?
??The transition to simplified connections is implemented using Multiple Point Constraints (MPC) that define displacement/force transmission.
?? While MPC is broadly used in industrial applications and readily available in simulation tools, its correct implementation is not that straightforward (despite an apparent ease to use):
?? many MPC types exist.
?? their usage comes with some implementation challenges we must be aware of.
?? MPC penalization is sometimes required for tuning.
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We have published a post discussing this topic on our website
It presents common MPC implementation strategies, warnings and some insights on their integration and manipulation in SDT.
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