Nonlinear Creep Damage Parameter Extraction for AA3003 Coolant Plate Joints
Extracting AA3003 braze joint creep damage parameters requires DIC strain mapping under multiaxial stress to prevent premature cold plate fluid leakage.
Stress Relaxation Test
Meaning
Standardized mechanical test procedures measure the decay of internal force over time in a specimen held at constant strain and elevated temperature. A stress relaxation test records the rate of load reduction as elastic strain converts into inelastic plastic strain within the material microstructure. Power distribution busbars and bolted electrical joints undergo relaxation testing to quantify contact force degradation across thermal cycling profiles.
Test data yield relaxation curves that feed numerical material models used in structural pack engineering. Tests apply to solid metallic conductors and structural polymers.
Displacement Control
Closed loop electromechanical test frames maintain fixed actuator position throughout test duration. Executing a stress relaxation test requires high precision strain control to prevent thermal expansion artifacts. Load cell sensors track decaying reaction force continuously.
Retention Calculation
Mathematical decay functions fit load loss curves to extrapolate long term joint force retention. Data from a stress relaxation test allow engineers to determine remaining clamping force after ten thousand operating hours. High initial stress accelerates early force decay rates.
Fastener Evaluation
Bolted busbar joints require minimum contact pressure to prevent electrical resistance increases and localized thermal runaway. Conducting a stress relaxation test on joint assemblies evaluates spring washer performance under continuous thermal exposure. Contact force degradation increases electrical joint resistance over time.
Executing a stress relaxation test defines long term contact pressure retention for high voltage electrical joints.