reliability_test_planner¶

class
reliability.Reliability_testing.
reliability_test_planner
(MTBF=None, number_of_failures=None, CI=None, test_duration=None, one_sided=True, time_terminated=True, print_results=True)¶ Solves for unknown test planner variables, given known variables. The Chisquared distribution is used to find the lower confidence bound on MTBF for a given test duration, number of failures, and specified confidence interval. The equation for timeterminated tests is: MTBF = (2*test_duration)/(chisquared_inverse(CI, 2*number_of_failures+2)) The equation for failureterminated tests is: MTBF = (2*test_duration)/(chisquared_inverse(CI, 2*number_of_failures)) This equation can be rearranged to solve for any of the 4 variables. For example, you may want to know how many failures you are allowed to have in a given test duration to achieve a particular MTBF. The user must specify any 3 out of the 4 variables (not including one_sided, print_results, or time_terminated) and the remaining variable will be calculated.
Inputs: MTBF  mean time between failures. This is the lower confidence bound on the MTBF. Units given in same units as the test_duration. number_of_failures  the number of failures recorded (or allowed) to achieve the MTBF. Must be an integer. test_duration  the amount of time on test required (or performed) to achieve the MTBF. May also be distance, rounds fires, cycles, etc. Units given in same units as MTBF. CI  the confidence interval at which the lower confidence bound on the MTBF is given. Must be between 0.5 and 1. For example, specify 0.95 for 95% confidence interval. print_results  True/False. Default is True. one_sided  True/False. Default is True. If set to False, the two sided confidence interval will be returned. time_terminated  True/False. Default is True. If set to False, the formula for the failureterminated test will be used.
Outputs: If print_results is True, all the variables will be printed. An output object is also returned with the same values as the inputs and the remaining value also calculated.
Examples: reliability_test_planner(test_duration=19520,CI=0.8,number_of_failures=7)
Reliability Test Planner results for timeterminated test Solving for MTBF Test duration: 19520 MTBF (lower confidence bound): 1658.3248534993454 Number of failures: 7 Confidence interval (2 sided):0.8output = reliability_test_planner(number_of_failures=6,test_duration=10000,CI=0.8, print_results=False) print(output.MTBF)
949.4807763260345