Carmakers narrow the gap between computer models and real vehicle crashes
Engineers have developed a more accurate way to simulate how vehicle bodies deform during crashes and stress tests by blending flexible body models with real-world measurements. The technique cuts through limitations of traditional computer simulations, helping manufacturers catch design flaws earlier and reduce costly physical testing cycles.
Originaltitel: A New Correlation Approach for Body Distortion of a Complete Vehicle Using MBD and Test Results
Fordonstillverkare och autonomous-fordonsutvecklare kan nu validera karossdeformationer långt snabbare genom en hybrid mellan simulering och testresultat. Saab och Knite presenterar en ny korrelationsmetod som kombinerar Multibody Dynamics (MBD) med flexibla kroppsmodeller importerade via Modal Neutral File (MNF), vilket ger betydligt bättre överensstämmelse med verkliga testförhållanden än traditionell linjär Finite Element Method (FEM). Metoden använder Multi Stethoscope-mätningar för att fånga tidshistorik av kroppsdistorsion i alla öppningar och tvärsnitt. Opening Distortion Fingerprint (ODF) ger kvasistatisk respons medan Operational Deflection Shape (ODS) återspeglar dynamisk beteende. Forskarna visar hur Component Mode Synthesis och Craig-Bampton-metoden påverkar korrelationsprecisionen. Tillämpningen på Waymos robotaxi demonstrerar praktisk nytta för utveckling av autonoma fordon. Denna ansats minskar utvecklingstid och kostnader för validering av karossstruktur.
<div class="section abstract"><div class="htmlview paragraph">By using a fully trimmed vehicle body as flexible body, imported through a Modal Neutral File (MNF), in a complete vehicle Multibody Dynamics (MBD) analysis, the simulation setup gets considerably closer to the test conditions compared to only using a linear Finite Element Method (FEM) approach. Since the MBD analysis includes gravity, rigid body modes of the vehicle and the nonlinear behavior of the wheel suspension, it brings the correlation between simulation and test to a new and more comprehensive level.</div><div class="htmlview paragraph">As correlation criteria, the results of the so-called Multi Stethoscope (MSS) are used. The MSS captures the time history of distortion in all body openings and cross sections and enables a detailed stiffness evaluation of the body using the so-called Opening Distortion Fingerprint (ODF). The ODF gives the quasi-static response while the Operational Deflection Shape (ODS), which is another result of the MSS measurements, reflects the dynamic response.</div><div class="htmlview paragraph">Apart from the different individual steps of this new correlation approach, the paper highlights the importance of considering Component Mode Synthesis (CMS) when embedding and evaluating a linear FE model of the fully trimmed body in the nonlinear MBD environment through an MNF. An example of CMS using the Craig-Bampton method shows the impact of the different parameters included in the CMS. Furthermore, a new graphical feature in combination with the ODS is presented which enhances correlation capability. Finally, an example shows how this new correlation approach can improve the simulation model of a newly developed robotaxi for Waymo.</div></div>