Hopkinson Bar Shock Testing to Isolate Projectile Catch Loads
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Solution Overview
Problem
Current shock testing methods for projectiles impose additional loads on the projectile unrelated to the actual shock event by using a catch system to arrest the projectile, which distorts the test results.
Innovation Solution
A pneumatic gun assembly coupled with a Hopkinson bar assembly and a magnetic catch system that propels a striker into the projectile, allowing it to decouple from the catch after shock transmission, minimizing additional loads and accurately simulating the impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an instrumented projectile is fired from an actual weapon system to evaluate shock loads, then the shock performance can be tested, but additional loads unrelated to the actual shock event are imposed on the projectile
Solution Approach 1:
The patent introduces a Hopkinson bar as an intermediary device between the projectile and the catch system. The bar transmits the shock load from the projectile impact to the catch system, while isolating the projectile from the additional loads that would otherwise be imposed by direct engagement with the catch system. This mediator allows accurate shock performance evaluation without the harmful additional loads.
Solution Approach 2:
The test system is segmented into distinct functional components: the projectile, the Hopkinson bar assembly, and the catch system. The Hopkinson bar acts as a separate transmission element that decouples the projectile from the catch system, allowing the shock event to be isolated and measured without contamination from the deceleration mechanism.
2Speed
If a catch system is used to arrest the projectile, then the projectile can be decelerated, but the catch system imposes additional loads unrelated to the actual shock event
Solution Approach 1:
The Hopkinson bar serves as a mediator between the projectile and catch system, allowing the catch system to perform its deceleration function while preventing the transmission of non-representative loads to the projectile. The bar absorbs and isolates the additional loads, ensuring that only the relevant shock event loads are imposed on the projectile.
3Reliability
If actual weapon system firing is used for shock testing, then real shock events can be simulated, but the complexity of the test apparatus increases
Solution Approach 1:
The patent creates a simplified copy of the actual shock event using a Hopkinson bar impactor system. Instead of requiring the full weapon system, the invention replicates the essential shock loading conditions through a controlled impact on the Hopkinson bar, which then transmits representative shock loads to the test article. This copying approach maintains shock event accuracy while reducing apparatus complexity.
Data Source
AI summary
A test assembly and method for performing a shock test of an article includes a pneumatic gun assembly, a Hopkinson bar assembly, a magnetic catch, and a support assembly. The support assembly suspends the article in alignment with the magnetic catch. The magnetic catch retains the article against the Hopkinson bar assembly. The pneumatic gun assembly includes a striker for propagating a shock through the Hopkinson bar assembly into the article.