Engineering topics

Wnuk, V. P.

Publications and source records attributed to Wnuk, V. P..

2 records

NASA NTRS1997

The Development of a PdCr Integral Weldable Strain Measurement System Based on NASA Lewis PdCr/Pt Strain Sensor for User-Friendly Elevated Temperature Strain Measurements

This report describes the development of a user friendly weldable strain gage employing the NASA Lewis PdCr/Pt wire strain sensor. The NASA sensors are pre-attached to Hastelloy X or Titanium alloy shims using name spray techniques developed under previous NASA programs. The weldable sensors are then pre-stabilized for 50 hours at 780 C in air. A weldable terminal and high temperature cable is then connected to the sensor and the assembly is pre-calibrated over the full test temperature range. Calibrated resistors are inserted into a bridge completion module at the cool end of the cable to condition the sensor in half or full bridge configuration. The sensor is attached to the structure using a common capacitive discharge spot welder. No additional high temperature stabilization or calibration is required. The resultant device is a pre-calibrated strain transducer which can be plugged into any common variety strain instrumentation.

Wnuk, S. P., Jr.↗

NASA NTRS1990

High Temperature Capacitive Strain Gage

Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

Wnuk, Stephen P., Jr.↗