ReliaSoft ALTA

Quantitative accelerated life testing data analysis techniques and ReliaSoft’s ALTA software tool enable you to:

• Understand and quantify the effects of stress (or other factors) on product life.
• Design accelerated tests that will be the most effective to achieve desired objectives.
• Significantly reduce the test time required to obtain reliability metrics for a product, which can result in faster time-to-market, lower product development costs and improved designs.

ALTA provides a comprehensive toolset for accelerated test planning and quantitative accelerated life testing data analysis, plots and reporting. Two versions are available:

• ALTA Standard provides the life-stress relationship models required to analyse accelerated life test data with 1 or 2 constant stresses.
• ALTA PRO offers advanced capabilities for analysing accelerated life test data with up to 8 simultaneous stress types where stress is constant or varies with time.

Both versions provide a complete array of utilities for designing accelerated life tests, evaluating the fit of the model, calculating reliability metrics, generating plots and performing related statistical analyses.

In quantitative accelerated life testing (QALT), the stresses that cause product failure are accelerated under controlled conditions to cause the product to fail in a shorter period of time without introducing additional failure mechanisms that would not occur under normal use conditions. Unlike qualitative accelerated tests (such as HALT/HAST), which precipitate failures in order to identify failure modes, QALT produces time-to-failure information that can be used to estimate the expected life of the product under normal use conditions.

When such tests are performed correctly, you can use mathematical models to extrapolate a use-level cumulative distribution function (cdf) for the product from the life data obtained under accelerated conditions. You can use this analysis to determine reliability, probability of failure, warranty time, mean life, B(X) life and other information about the expected life of the product.

ALTA’s data entry spreadsheets support Complete, Right Censored (Suspended) and Interval or Left Censored data, entered individually and in groups, with up to eight stress types (depending on the life-stress model). In addition, the Monte Carlo utility provides randomly generated data sets based on a specified model, distribution and parameters.

ALTA supports data analysis with the Weibull, lognormal and exponential distributions combined with the following life-stress relationships: Arrhenius, Eyring, Inverse Power Law, Temperature-Humidity and Temperature-NonThermal. ALTA PRO supports additional multi-stress and time-varying stress models, including Proportional Hazards, General Log-Linear (with user-defined transformations), Cumulative Damage and Generalized Eyring.

In ALTA PRO, you can define stress profiles that vary with time, such as step-stress, ramp-stress, etc. Enhanced in Version 7, the Cumulative Damage model now supports analysis of multiple time-varying stresses.

ALTA uses Maximum Likelihood Estimation (MLE) for parameter estimation. The QCP and Function Wizard quickly return calculated reliability results (such as reliability given time, mean life, acceleration factor, BX life, etc.) based on the data analysis and your inputs. Confidence bounds are available for all calculated results and parameters.

ALTA automatically generates a complete array of reliability plots, with customizable plot settings. This includes Probability, Reliability vs. Time, pdf, Life vs. Stress, Acceleration Factor vs. Stress, etc. Plots are metafile graphics (*.wmf) that can be annotated and used in your reports and presentations.

This utility implements the complex mathematical models required to design an effective accelerated life testing plan, which accounts for the type of stress, method of applying stress, stress levels, number of units to be tested at each stress level and an applicable life-stress model.

• Weibull++
• DOE++
• BlockSim
• RENO
• Xfmea
• RCM++