Engineering Papers⌕ Search

Engineering topics

Hoffman, I. S.

Publications and source records attributed to Hoffman, I. S..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Miniature biaxial strain transducer

A reusable miniature strain transducer for use in the measurement of static or quasi-static, high level, biaxial strain on the surface of test specimens or structures was studied. Two cantilever arms, constructed by machining the material to appropriate flexibility, are self-aligning and constitute the transducing elements of the device. Used in conjunction with strain gages, the device enables testing beyond normal gage limits for high strains and number of load cycles. The device does not require conversion computations since the electrical output of the strain gages is directly proportional to the strain measured.

Hoffman, I. S.↗
NASA NTRS1974

Miniature biaxial strain transducer

Transducer is completely reusable and permits relocation to alternate points to be accomplished quickly. Size permits measurements to be made simultaneously over small areas and yields outputs directly proportional to strains measured. Transducer verifies elastic modulus, Poisson's ratio, and principal strain axes on materials.

Hoffman, I. S.↗
NASA NTRS1973

A self-supporting strain transducer

Self-contained mechanical measuring system is handmounted by simply compressing installation spring and inserting device into hole of matching size. It is self-aligning as each contact pin maintains constant contact with surface being measured. Strain level is controlled by design to provide for measurements over almost unlimited number of load cycles.

Hoffman, I. S.↗
NASA NTRS1971

Static and dynamic load measurements in aerospace decelerator canopy fabrics with metal foil strain gages.

A test program was conducted to determine the feasibility of using conventional metal foil strain gages to measure load-time relationships on thin fabric membranes while these membranes were loaded under simulated aerodynamic decelerator conditions. Uniaxial and biaxial tests were made at fabric strain levels up to about 10%. Loadings were made both statically and dynamically, with the fastest load time being 0.015 second for zero to full load on uniaxial test specimens. For the biaxial tests, plane strain conditions were assumed, and by using experimentally determined strain-load relationships, principal loads were determined from the perpendicularly oriented strain-gage pairs. Although the complex stress-strain behavior of decelerator fabrics prevents the attainment of normally expected strain-gage accuracy, utilization of the techniques described can lead to meaningful measurements for the decelerator stress analyst.

Hoffman, I. S.↗