Accession Number : ADA252375
Title : Measurement of Close-in Blast and Shock Loads
Descriptive Note : Contractor rept.
Corporate Author : SRI INTERNATIONAL MENLO PARK CA
Personal Author(s) : Gran, James K ; Holmes, Bayard S
Report Date : Jul 1992
Pagination or Media Count : 139
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.
Descriptors : *MEASUREMENT , *BLAST LOADS , *ARMORED VEHICLES , VALIDATION , TOOLS , COMPUTERS , LAYERS , POLYMERS , EDGES , EXPLOSIVE CHARGES , BLAST WAVES , CAVITIES , TARGETS , STEEL , SURFACES , PROFILES , HIGH STRENGTH , PRESSURE , STRAIN GAGES , MANGANIN , YTTERBIUM , WELDING , BONDING , CALIBRATION , VEHICLES , GAGES
Subject Categories : Explosions
Distribution Statement : APPROVED FOR PUBLIC RELEASE