Design of a Shock Test Machine for Encanistered Missiles
Dr. Jon Yagla, NSWCDD

Abstract:
A set of fixtures consisting of a carriage, cradle, simulated plenum, and simulated deck have been designed for the WOX (White Oak Experimental)-7B shock test machine to enable shock qualification of missiles and canisters for use in the MK 41 VLS (Vertical Launching System). 

The design process began with simple “proof of concept” experiments with the WOX-7B machine and a torpedo test fixture to show how a three-axis test could be developed.   This led to computer analyses to better define WOX input and the WOX braking system.  Felt programmer pads were also studied in the laboratory and modeled with computers.  The results showed that a larger system with more carefully designed fixtures would have a good chance of meeting ship shock requirements.

The next step was constructing a very elaborate Abaqus finite element model of the “proof of concept” test hardware.  The model made good predictions of the experiments.  With confidence established in the modeling approach, a full size design with accurate representations of the MK41 VLS deck and plenum was constructed.

The biggest challenge in the design was to get larger motions at the deck than the plenum.  Shock amplification was needed.   The cradle was designed to whip at the deck end to get the required motion.  A detailed design was carried out, and again an elaborate Abaqus model was developed.  The model showed expected response changes and sensitivity to the various possible settings.

The machine and all the needed parts were then built and calibration tests were performed, meting the requirements for simulating shipboard shock on cruisers and destroyers.

The paper describes the team approach, how the team was organized, who the players were, and how they approached the design process.  Formal project management methods included using a professional task manager, scheduling and resource management computer tools, and subject matter experts from various disciplines.  The team pulled together experts in computer modeling, experimentation, launcher equipment design, missile design and ship shock testing.  The participants were a blend of both government and industry personnel, spanning the range from beginning helpers to PhD analysts, to senior government program managers, each performing a vital role.

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