CRASH ENERGY ABSORPTION WITH SOLID EJECTION MATERIAL (SEM) SHOCKS

 U.S. PATENTS # 5,875,875 & # 6,135,252

DESIGN SUMMARY 

The SEM shock isolator technology is a greatly simplified energy absorption system that utilizes the same high injection molding pressures that are required to force plastics and elastomers (e.g. HD Polyethylene, Neoprene Rubber, etc.) or simply polymers, into molds or dies. The required injection molding pressures for various polymer types, can vary from 2,000 psi up to an incredible 35,000 psi! The SEM technology allows for several means of load control. Of course piston area is a major load performance factor but for a set piston area, an ejection material's pressure and flow behavior, can be controlled by simply altering the size and placement of the ejection porting and/or by changing the ejection material’s durometer. While still other design factors can be employed for performance tailoring (e.g. piston face design, fiber inclusion, friction coefficient tailoring, etc.), the control of just two variables, those being the ejection port design and material selection, will still provide an SEM shock with an infinite range of load control, with little or no change to the overall manufacturing costs.

The production cost of the SEM shock isolator is extremely low as compared to any other existing design type. One of the major areas for cost savings is the substantial reduction in the number of parts, for each SEM shock assembly. Since each part requires engineering design and drawings, stress modeling, tooling, manufacturing processes, raw material orders, raw material spec requirements, material tracking, finish part tracking and finally, since each part adds to the assembly time and reduces overall system reliability; each part added, will significantly add to the overall manufacturing costs. And one should not forget that even if the part count is reduced in a conventional shock isolator design, through part consolidation, that the overall part complexity will still add to the overall system cost.

As a comparison, SEM shock isolators require 80% fewer parts than the conventional hydraulic or pneumatic shock isolator. Also, many of the parts are simple extruded, roll formed, or stamped parts which require no complex machining. And not one SEM part requires tight tolerance controls, since there are no fluids or gasses to leak.

In summary, the SEM shock or energy absorption technology can be tailored to do any job with an extremely high system reliability, and do it all at a small fraction of the cost of any conventional shock technology. The improved safety factor and the substantial reduction in collision damage costs, which is achieved through the employment of the SEM technology, will surely decrease insurance costs across the entire transportation sector. Such cost savings will help provide a strong motivation for the various transportation industries, to implement safety upgrades in their current and future transit systems. So with all of these very positive attributes, a broad and sizable market for the SEM technology will be assured.

 

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