Naval Shock Analysis (DDAM): Altair HyperWorks vs. SOLIDWORKS Simulation

by Shaun Bentley

The Dynamic Design Analysis Method (DDAM) is a methodology developed by the U.S. Navy for testing shock loading from underwater explosions. Both Altair HyperWorks and SOLIDWORKS Simulation Premium contain the capability to test your designs using this method. In this blog, we’ll compare Altair HyperWorks vs. SOLIDWORKS Simulation and look at key features from both tools so you can decide which tool is best for you. 

In order to run an analysis using DDAM, the following four steps must be completed in the following order:

  1. Modal Analysis
  2. Shock Load Generation (HyperWorks ONLY!)
  3. Response Spectrum Analysis
  4. Results Reporting

Step 1: Modal Analysis

Both HyperWorks and SOLIDWORKS Simulation can calculate resonant frequencies and mass participations. Below are the modal results of the same 3’ x 4’ aluminum sheet mounted on the deck of a ship. 

Altair HyperWorks Modal

Altair HyperWorks Modal Results

SOLIDWORKS Simulation Modal

SOLIDWORKS Simulation Modal Results

With the same geometry and setup, the results will be roughly equivalent between these two tools.

Resonant Frequencies and Mass Participations

Resonant Frequencies and Mass Participations (left: Altair HyperWorks; right: SOLIDWORKS Simulation)

Many users may find that it’s easier to make design changes and run these studies in SOLIDWORKS Simulation due to its CAD-embedded interface. On the other hand, if models are large, some of the advanced meshing features in HyperWorks can help you save time overall. 

Step 2: Shock Load Generation (HyperWorks ONLY!)

After you retrieve the modal analysis results from the previous step you must then use these results to generate a shock load. HyperWorks gives you a special utility to generate the shock load using the DDAM utility shown below. 

Altair HyperWorks DDAM Utility

Altair HyperWorks DDAM Utility

Since this utility is not available in SOLIDWORKS Simulation, resourceful Simulation users will need to consult the equations listed in the NRL Memorandum Report 1396 in order to generate their shock loads.

Step 3: Response Spectrum Analysis

Once you have your shock load, you can now use this load to run a Response Spectrum Analysis and measure peak stresses and deflections. Since SOLIDWORKS Simulation cannot generate the shock load spectrum from the previous step, I created a spreadsheet that would create the spectrum. 

As expected, the results from running this final study look practically identical between both tools.

Altair HyperWorks peak displacement of 1.211 inches

Altair HyperWorks: Peak displacement of 1.211 inches

SOLIDWORKS Simulation Peak displacement of 1.211 inches

SOLIDWORKS Simulation: Peak displacement of 1.211 inches

Step 4: Results Reporting

Both software packages are capable of producing results that should satisfy the requirements of DI-ENVR-81030.

The input files used by HyperWorks (HW_Sample.fem)  should be recognizable to agencies requesting DDAM and with Altair’s HyperView, users can spell-out all the data in the report clearly and visually. 

On the other hand, some further degree of customization of the SOLIDWORKS Simulation results and exports will likely be needed to make sure the data is recognized, and the requirements are completely satisfied. SOLIDWORKS Simulation can export a printout of the input data (SS_Sample.DAT) in several formats to include details like node point locations.

SOLIDWORKS Simulation exports

Nodal forces and connector forces may be missing from these exports and may need to be exported manually from some plots in the SOLIDWORKS Simulation interface. 

Altair HyperWorks vs. SOLIDWORKS Simulation Summary

In summary, Altair HyperWorks has several advantages over SOLIDWORKS Simulation nearly every step of the way. The table below summarizes a few of those key advantages. 

Conclusion

The comprehensive suite of tools available with Altair HyperWorks allows users to run their analysis using DDAM from start to finish. The DDAM utility is a great bonus for users who don’t want to wrestle with determining their shock loads. Some of the advanced results reporting capability give users flexibility when it comes to submitting their results. 

Also, Altair’s suite of tools allows users to run shape optimizations on their DDAM projects. Due to many of these advantages, GoEngineer recommends Altair HyperWorks to your team if you plan on using DDAM on your designs. 

For users who are ok with generating their own shock loads and who prefer the intuitive SOLIDWORKS environment, SOLIDWORKS Simulation Premium can also do the job. This tool makes it easy to test design changes since studies can be automatically re-meshed and re-run after using SOLIDWORKS to change features and dimensions in your model. 

Would SOLIDWORKS Simulation or Altair HyperWorks benefit your organization? Fill out the form below and a Simulation Expert from GoEngineer will contact you shortly. 

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