Measurement of Close-in Blast and Shock Loads
Abstract
On this contract, SRI International is developing a flatpack stress gage for BRL to use for measuring blast pressure histories on armored vehicles very near explosive charges. A flatpack stress gage comprises piezoresistance foil elements, such as manganin or ytterbium, encapsulated in a thin polymer layer and sandwiched between two steel strips welded at the edges. This gage is very well suited for measuring blast pressure loads on the surface of an armored vehicle because it can be attached to the target with no penetrations (by welding or bonding with epoxy) and it presents a very low profile obstacle to blast waves. In this project we accomplished two major developments to make flatpacks usable for this application. First, the flatpack design was improved by using a very-high-strength steel case, confining the piezoresistance elements in a shallow cavity to mitigatestrains, incorporating three piezoresistance elements in a single gage to measure inplane strains, and reducing the size of the gage so that all the elements fit within a 5-mm radius. Second, an analytical procedure was derived and a computer code was written to interpret resistance histories from three piezoresistance elements under nonuniaxial strain conditions based on the constitutive and piezoresistance properties of the elements. With these developments, the flatpack gage is now a usable tool for many blast-load measurement problems although additional calibration and validation experiments we recommended.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1992
- Accession Number
- ADA252375
Entities
People
- Bayard S. Holmes
- James K. Gran
Organizations
- SRI International