Demos

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We’ve said it on our websites more than once, we repeat it once again:

The principals at McHenry Software, Inc. (MSI), Raymond & Brian McHenry, have been active in the field of highway safety research for a combined period of over 90 years. In that time they have performed research for NHTSA, FHWA, NTSB, public and private research organizations and MSI internal development through which they have invented, developed and enhanced the state-of-the art of collision and rollover simulation programs and other reconstruction tools. The programs include CRASH, SMAC and HVOSM which are acronyms for accident simulation and collision reconstruction programs invented by Ray McHenry and on which Ray and Brian have extensively researched, developed and published. These programs form the foundation for many of the accident reconstruction and simulation tools in widespread use today.

Ray and Brian have devoted our professional lives working to create and improve accident reconstruction and simulation tools for highway safety and litigation purposes. We have created a user friendly, easily understandable and quickly presentable product. We plan to continually improve and extend the capabilities of the program for you, our McHenry Software licensee.

We can best improve our programs if we listen to you, our clients. Let us know what you like about the product, what you don’t like, any suggestions for improvement will be considered and prioritized.

Thank you for your interest in McHenry Software technology.

These are few of the comments and testimonials from our users:

Few hi-lights to show it is easy to use.

• Simplification of the process of applying a 3D simulation & reconstruction
• 3D inputs automatically created based on 2D inputs: vehicle make, model, year, & content weight (occupants & cargo)
• With automatically generated 3d vehicle inputs accuracy within ± 10%
• More refined inputs can be specified however not required

See the Simulation being created in 3 Minutes

AUTOMATIC ITERATION TO IMPROVE EVIDENCE MATCH AND SIMPLIFY THE MSMAC3D PROCESS

As any SMAC user is aware, many iterations of the SMAC program may be required to go from an initial approximation to an acceptable match of the measured trajectory and damage targets. Throughout the iterative process, the impact speeds and impact speed change results may not change significantly. Also, what constitutes an acceptable match can vary widely among users. Sometimes the focus is on a detailed match of the positions of rest; sometimes the focus is on a match of damage locations and extents on the vehicles. There is currently no standardized measure of the correlation of simulation results with the accident evidence.

Since the initial development of the SMAC program, there has existed a need to simplify the application process. The ultimate simplification would entail an automatic iteration procedure. Optimization techniques applied to the evidence match can serve to reduce the required time and effort and, also, can achieve greater uniformity of the evidence interpretation.

The working hypothesis of the automatic iteration of SMAC is that a unique set of impact conditions is required to achieve an acceptable match of all of the documented evidence (both damage and trajectory). The use of quantitative measures of the overall “fit” to the documented evidence and applications to experimental crash tests provided a means of proving the hypothesis, as well as demonstrating reconstruction accuracy and convergence rates. Note that successful efforts on automatic iteration in the msmac2D case were reported in Ref 13 (Fig 20 -23). That research proved the feasibility of an automated procedure for achieving a “best match” of measured evidence, starting with CRASH-type linear momentum/damage analysis initial approximations. Small deviations from a perfect “match” are, of course, imposed by the existing limitations of the SMAC computer program and by any inaccuracies in the reported evidence.

In the reported results the automatic iteration/optimization of msmac2D was demonstrated to successfully converge toward evidence matches in a variety of impact configurations. With measured evidence from full-scale tests on flat surfaces the automatic iteration procedure of msmac2D produced correlation of impact speeds and impact speed changes with deviations in individual results of less than approximately ± 10%.

The research confirmed that the initial approximation of the CRASH program, or any proper combination of linear momentum and damage analysis solution procedures, should provide an adequate initial approximation from which an automatic iterative/optimization procedure of msmac2D can be used to determine the impact speeds and impact speed changes within ± 10%.

For 3D simulations the only change required was to add automatic iteration/optimization of msmac3D results is to simply have the control algorithms use the msmac3D program instead of msmac2D program for iterating/optimizing towards a unique solution. The msmac3D automatic iteration/optimization program is currently in testing and will be included in the msmac3D release.

The msmac3D setup automatically generates all required 3D vehicle input definitions based on the vehicle make/model and any other supplemental information and the user can easily include 3D terrain information if applicable. Upcoming extensions of the automatic iteration/optimization routine will be to include comparisons with measured tire mark information and an extension to iterate/optimize on rollover and other single vehicle accidents.

Automatic Iteration solutions of a SMAC Reconstruction of a sample RICSAC Test.

Automatic Iteration Results with Crash Test results on Impact Velocity (first) and Impact Speed Change (second).

Comparison of msmac automatic iteration correlation factor “score” with maximum error.

An obstacle to detailed and scientific simulations in the past has been the complexity of highway vehicles (3D inertial properties, suspensions, tires, structural crush behavior) and the highway environment (geometrics, topography, obstacles). Proprietary extensions of mSMAC3D include routines that automatically generate default approximations for the required three-dimensional vehicle inputs (e.g., suspension & tire properties, roll and pitch moments of inertia) from the plane-motion 2D simulation inputs combined with the vehicle make, model and loading. These initial input approximations combined with the ability to overwrite any inputs for which measured values are available provides a comprehensive and efficient setup to evaluate motor vehicle collisions.

Msmac3D has achieved impressive accuracy in the general case using automatically approximated vehicle properties as it provides impact speed and impact speed change results that correlate within +/‑10% of the corresponding measurements in more than 25 instrumented collision and rollover tests. These tests come from a variety of sources including the following:

• Smith, R. A., Noga, J. T.
  “Examples of Staged Collisions in Accident Reconstruction“,
  from Highway Collision Reconstruction,
  The American Society of Mechanical Engineers, Nov. 1980

• McHenry, B.G, McHenry, R.R.,
  “RICSAC-97, A Reevaluation of the Reference Set of Full Scale Crash Tests“,
  SAE Paper No 97-0961, Detroit 1997

• Larson, Smith, Werner and
  Fowler, “Vehicle Rollover Testing, Methodologies in Recreating Rollover Collisions“,
  SAE Paper 2000-01-1641

• 2002 SCARS Test2

• 2010 ARCCSI Test8

• Toyota PU Rollover Test

• 2014 NAPARS Test 2

• 2011 SATAI Offest

• 2008 SCARS Crash 3

• 2013 Tennessee Highway Patrol

• 2007 SCARS Crash 4

• 2007 NYStars

• http://tucrrc.utulsa.edu/,
  University of Tulsa’s Crash Reconstruction Research Consortium

A paper will be published by McHenry Software providing more information and documentation on these validation tests shortly after the official release of the msmac3D program.

Also please read paper prepared for the 2015 IPTM Special Problems Conference

“The Proper Use of Simulation Technology for Collision and Rollover Reconstructions and Highway Safety”

The following are some time history plots of comparisons of msmac3D time history predictions from that IPTM paper with the full scale test measurements. These comparisons demonstrate good correlation of the predicted roll, pitch and yaw responses with the full scale test measurements.

In the Graphs, Blue Solid lines are full scale test measurements and the other dashed lines are the predicted results of mSmac3D.