Computer program, system and method to specify sinusoidal vibration tests for product durability validation

A computer system for determining the testing profile for accelerated laboratory sinusoidal vibrational testing of a product in accordance with an application program that controls testing equipment coupled to and for testing the product in accordance with test signals, the system comprising:

• a control processing unit coupled to and for controlling the testing equipment,
• a memory for storing the application program for controlling the central processing unit,
• program means for selecting a logarithmic type frequency sweep covering the range of from approximately 5 Hz to 200 Hz in approximately 10 minutes,
• program means for developing a simplified composite Power Spectral Density function PSD.sub.j, including scaling coefficients a, b, c and d, representative of the PSD for random vibration loadings in expected field vibration levels in the frequency bands defined by approximately 0 Hz, 50 Hz, 100 Hz, 150 Hz and 200 Hz,
• program means for developing the acceleration function G.sub.T (f), corresponding to PSD.sub.j and using the PSD scaling coefficients, for producing on the product the test acceleration forces corresponding to the PSD.sub.j function,
• program means for calculating the stress response curve H(f) for the product representative of the transmissibility function from the input acceleration forces to the local vibration stress forces,
• program means for selecting the number of frequency sweeps equal to approximately 18 and then calculating the acceleration forces G.sub.u required for implementing G.sub.T (f) from the relationship ##EQU27## program means for generating said test signal for testing the product using the selected sweep type, sweep rate, G.sub.u acceleration forces and N.sub.w number of frequency sweeps, to validate the required performance lifetime for the product when no test failures are observed over all of the N.sub.w test sweeps.

A computer readable memory for scoring an application program that controls a central processing unit for determining the testing profile for accelerated laboratory sinusoidal vibrational testing of a product, by performing the steps of:

• (i) defining the type and rate for the frequency sweep too be used in the accelerated testing,
• (ii) instructing the central processing unit to develop a simplified composite Power Spectral Density function PSD.sub.j, including scaling coefficients, representative of the PSD for random vibration loadings in expected field vibration levels,
• (iii) instructing the central processing unit to develop an acceleration function G.sub.T (f), corresponding to PSD.sub.j and using the PSD scaling coefficients, for producing on the product the test acceleration forces corresponding to the PSD.sub.j function,
• (iv) instructing the central processing unit to calculate the range of acceleration forces G.sub.u required for implementing G.sub.T (f) from the relationship ##EQU28## and then to select the number of frequency sweeps N.sub.w based on the capabilities of the testing equipment and the testing time available,
• (v) instructing the central processing unit to recalculate the acceleration forces G.sub.u based on the scaling coefficients and the selected value of N.sub.w, and then
• (vi) instructing the central processing unit to control the testing of the product using the selected sweep type, sweep rate, G.sub.u acceleration forces and N.sub.w number of frequency sweeps, to validate the required performance lifetime for the product when no test failures are observed over all of the N.sub.w test sweeps.