Project 1 - High-G Accelerometer
Development
HIGHG Shock Test Fixture
Figure 1. HIGHG shock test fixture. The striker
assembly is suspended from a pivot bearing. When released,
the striker impacts the carrier rod, transferring much of its energy to
the rod, and accelerating the rod through the linear bearing.
Figure 2. Mounting of the UUT and dynamic test PWB
to the carrier rod nose piece, rear view. The nose piece projects
through an access hole milled in the dynamic test PWB, and is epoxied onto
the back of the UUT.
Figure 3. Mounting of the UUT and dynamic test PWB
to the carrier rod nose piece, front view. The UUT is connected to
the dynamic test PWB by means of 48 cylindrical spring contacts.
Test instrumentation connects to the dynamic test PWB through one of the
two board-edge connectors provided.
Figure 4. Pivot bearing assembly. The bearing
and pillow block assembly provide the pivot point for the striker arm.
The length of the striker arm is adjustable to allow alignment of the striker
and the carrier rod face.
Figure 5. Carrier rod and linear bearing, oblique view.
The case hardened carrier rod is constrained to linear motion by means
of a double linear bearing. The travel is limited by a nylon cord
which allows free linear travel for approximately 10 cm, beyond which the
carrier rod is captured to keep it from exiting the bearing.
Figure 6. Striker assembly and carrier rod. The
rounded nose of the striker assembly provides a small contact area to the
carrier rod. The carrier rod is case-hardened mild steel, which provides
an elastic single point contact between the striker and carrier rod.
Figure 7. Carrier rod, linear bearing and striker,
top view. The linear bearing is held in place by concrete anchors
which provide a constant strike position with relation to the striker assembly.
HIGHG Instrumentation Electronics
Figure 8. Mounting of the UUT to the dynamic test PWB.
The UUT is connected to the dynamic test PWB by means of 48 cylindrical
spring contacts. Test instrumentation connects to the dynamic test
PWB through one of the two board-edge connectors provided. The 50-pin
connector on the left connects to the static test PWB, to allow direct
observation of the amplified accelerometers utilizing standard lab test
equipment. The 24-pin connector on the right connects to the automated
data collection system which records accelerometer output for computer
analysis.;
Figure 9. Static test PWB. The Static test PWB
is connected to the dynamic test PWB by means of the matching 50-pin edge
connectors. The dynamic test PWB provides the low-noise amplification
required to optimize the signal-to-noise ratio and allow testing of high
acceleration accelerometers at low levels. Oscilloscope probes can
be inserted directly into the special test points to optimize signal coupling
and reduce ground noise.
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