George Laird's blog

Impact Analysis of Additive Manufactured Lattice Structures

We are pleased to announced a year-long contract award from the US Army Natick Soldier Systems Center (NSSC) to continue the investigation of additive manufactured materials for improved blunt force protection in helmet systems.  Our role is to work with Natick’s engineering team to simulate the impact behavior of additive manufactured 3D lattice systems.  In prior work  (see our Case Study: Impact Analysis of Additive Manufactured Lattice Structures) we discovered that getting the material characterization correct was not easy.  In this new work, we’ll revisit that whole process and look into manufacturing variability of the additive materials from bulk samples down to thin noodle-like structures that are necessary to for the 3D lattice structures of the foam replacement pads.

FEA Impact Analysis of Additive Manufactured 3D Lattice Structures for Improved Blunt Force Protection

LSTC Releases LS-DYNA R11.0.0

LSTC Releases LS-DYNA R11.0.0Livermore Software and Technology Company (LSTC), Livermore, CA has recently released LS-DYNA R11.0.0. This release is ready-to-use and is our baseline at Predictive for implicit and explicit work. It is stable and is not a classic xx.0.0 release as is common in the software industry.

Let me explain why: LSTC’s is very transparent about how it develops LS-DYNA and any published release (see release notes.)

So what does this really mean? A released LS-DYNA version is not a “fresh, hot-out-of-the-developers-oven” version of the code. It has gone through months and months, if not years of bug fixes by the development team and user community. The process is quite rigorous, for example, once the LSTC team decides enough-is-enough, a branch is somewhat sealed off from any new major code changes (i.e., R11.xxxxx). While this branch is static, the Development Team continues code development under the designation of Dev_XXXXXX. As the code is fine-tuned and bugs removed, applicable updates are made to the branch and if applicable to prior released versions of the code. At this stage, if the code is deemed ready by the Team, it is run through a suite of verification problems and released to the simulation community. One will note that through-out this whole process, there is no VP of marketing or sales pushing the team to release, it is only released when it is right.

Why LS-DYNA R11.0.0?

CFD Analysis of CRRC's LACMTA Heavy-Rail Rapid Transient Vehicle

This has been an on-going project for our CFD consulting services team during most of 2018. As we all know, there is nothing like a “site visit” to meet your fellow engineers and see hardware. In early September, Drs. Laird and Hearn visited the CRRC Changchun Railway Vehicles Co., Ltd in Changchun, China. This is a cooperative project where Predictive has partnered with Hengstar Technology, Shanghai, China (Dr. Lu Hongsheng is shown on the left of our group photo). The project work requires a complete flow and thermal analysis of Los Angeles County Metropolitan Transportation Authority (LACMTA) new passenger transit vehicle. The CFD requirements are a notch above normal specifications with tight controls on air flow volume, maximum velocity and distribution. Thermal analysis looks at vehicle cool down on hot days (transient thermal with solar radiation and lots of internal heat generation) and also thermal management within the electronics and motor drive bay at bogie level.  All simulation work will be validated against vehicle mock-ups.

 

Changchun, China – CRRC’s Manufacturing Site

CFD Analysis of CRRC’s LACMTA Heavy-Rail Rapid Transient Vehicle 01

CRRC’s Bullet Train

STAR-CCM+ CFD HVAC Flow Analysis of Passenger Transit Vehicle

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