Projectile Soft Catch

em launch

Testing electronics at a whole new level

As miniature electronics and other small devices continue to find their way into new and sometimes harsh operational environments, shock testing or acceleration testing of these devices has become more important for quantifying and demonstrating operational reliability.

A recent article, “Measuring and Simulating Bombs Bursting in Air”, discusses several different traditional shock or acceleration testing methods of hardware.  However, the testing methods mentioned can result in high frequency acceleration oscillation profiles, and there are certain applications where this type of testing is not representative, and a single cycle, more controlled acceleration profile is required.

CEM is leveraging its research expertise to provide an alternative testing approach.  EM launch provides a controlled pulse shape with a single acceleration rise and a controlled decay.  The launch of a bullet or large projectile is an example application where high amplitude single pulse testing would be appropriate.  An EM launcher, or railgun, utilizes a high transient current pulse to magnetically accelerate a sliding armature.  The drive force of the armature can be utilized to accelerate a test article.  Research at CEM over the past several decades has proven railgun performance can be well characterized and understood, with very tunable amplitudes and rise times for the acceleration profile.  This type acceleration profile, shown in Figure 2, is very different from the high-frequency shock testing discussed previously.

 

em system profile

Figure 2. Typical Acceleration Profile for an EM Launcher System

 

The rise time and duration at peak of the acceleration profile can be tailored to meet operational requirements for the test article.  An application where this type of acceleration testing is important is the development of miniature, gee hardened, electronic packages that are required in today’s smart and guided munitions.   Unlike the pyrotechnic or impact shock testing where the test article remains stationary while the impact energy has decayed to zero, EM launch acceleration testing imparts a velocity on the test article.  If the test article requires post-shock inspection to verify its performance, then the accelerated test article must be stopped utilizing a “soft-catch” recovery system to prevent damage during deceleration.  CEM has developed a fully demonstrated soft-catch recovery system capable of being tuned to accommodate different masses at different velocities.  CEM’s existing test fixture can accommodate launch articles of varying size, and is currently combined with the tunable soft-catch recovery system to enable post-shock inspection.