General Motors Company

Dynamic Sealing Stress Measurement for Powertrain Sealing Systems - Issue 4; English
 N GMW3137

Annotation

Introduction

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. This procedure describes the continuous measurement of stress (distribution) between the static gasket, O-ring or seal and joint surfaces using an electronic sensor film (e.g., Tekscan, FlexiForce Division). Stress measurement is a change in the sensor’s electrical resistance as a function of load. The sensor’s multiple contact points create a grid or stress distribution response. The changing (dynamic) force on a gasket given the tightening method, temperature, and sensor capability is observed (visual display) and measured.

Applicability.

Differences from GMW3152. GMW3152 (Static Sealing Pressure Measurement for Powertrain Sealing Systems) uses pressure sensitive micro-encapsulated color forming film, measuring only the maximum pressure under specified assembly conditions. This procedure is used where a more detailed level of surface contact pressure analysis is needed.

Test results may be used to verify finite element analysis stress results.

Useful for comparing component elements, e.g., various torque sequences or effect of torque on flange distortion and contact seal force.

Limitations. For joints larger than the sensor, use multiple sensors (butt joint) and combine the pressure maps to provide a total load distribution.

Consult the sensor manufacturer on calibration, accuracy, resolution and drift with used sensors. Replace if measurement problems cannot be resolved.