ALTA Features Overview

This topic provides a brief overview of the major analysis, data management and reporting capabilities provided by ALTA.

You can also review an introduction to the Synthesis Platform and a list of what's new in ALTA Version 8.

Quantitative accelerated life testing techniques, used in conjunction with powerful accelerated life data analysis methodologies, give design and reliability engineers the power to significantly reduce test times and produce more robust designs. This can, in turn, provide faster time to market, lower product development costs, lower warranty costs and a host of other tangible and intangible benefits. ReliaSoft's ALTA software provides a comprehensive toolset for accelerated life test planning and quantitative accelerated life testing data analysis. ALTA is available in two versions:

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

Accelerated Life Testing Data Analysis

ALTA provides all the tools and options you will need for accelerated life testing data analysis. It is designed for use with complete (time-to-failure), right censored (suspended), interval or left censored data. Data can be entered individually or in groups.

ALTA Standard gives you a choice of the following life-stress relationships:

Arrhenius: a single stress model typically used when temperature is the accelerated stress.
Eyring: a single stress model typically used when temperature or humidity is the accelerated stress.
Inverse Power Law (IPL): a single stress model typically used with a non-thermal stress, such as vibration, voltage or temperature cycling.
Temperature-Humidity: a double-Arrhenius model that is typically used when temperature and humidity are the acceleration variables.
Temperature-Nonthermal: a combination of the Arrhenius and IPL relationships that is typically used when one stress is temperature and the other is non-thermal (e.g., voltage).

In addition, ALTA PRO offers four other models for more advanced applications:

Generalized Eyring: a variation of the Eyring relationship that is typically used when both temperature and humidity are accelerated.
Proportional Hazards: analyzes data with up to 8 stress types using the Exponential relationship for each stress. It also allows the use of zero as a stress value, which enables the analysis of data with indicator variables (e.g., 0 = on/off and 1 = continuous operation).
General Log-Linear: supports the analysis of data with up to 8 stress types and provides the flexibility of specifying the life-stress relationship (Arrhenius, Inverse Power Law or Exponential) for each stress.
Cumulative Damage: analyzes data with up to 8 stress types and/or situations where the stress varies with time.

You can select to combine these life-stress relationships combined with an underlying Weibull, Exponential or Lognormal life distribution. If you are not sure which is appropriate for a given data set, the convenient Distribution Wizard automatically performs multiple goodness-of-fit tests in order to rank the available distributions.

Maximum Likelihood Estimation (MLE) is used for all parameter calculations. ALTA also provides Fisher Matrix confidence bounds for parameters, calculated results and plots.

The software provides a complete array of Calculated Results and Plots based on the analysis. For accelerated life testing data analysis, this includes:

Reliability or probability of failure
Reliable life (i.e., time for a given reliability, also called "warranty time")
BX% life (i.e., time for a given unreliability)
Mean life
Failure rate
Acceleration factor
Probability plots and pdf plots
Life vs. stress, acceleration factor vs. stress, and standard deviation vs. stress plots
Residuals plots
Three-dimensional surface plots such as reliability vs. time vs. stress

Time-Dependent Stress Profiles

As described in Time-Dependent Stress Profiles, the cumulative damage life-stress model (available only in ALTA PRO) can handle data from tests where the stress varies with time (e.g., a step-stress or ramp-stress profile). You can define and store any number of stress profiles, then easily assign the appropriate profile to each point in an ALTA data sheet. Each segment in a profile can be associated with a specific stress value (e.g., temperature is 310 K from 0 to 100 hours and 320 K from 101 to 200 hours) or a time-dependent function (e.g., start from a temperature of 310 K and then increase by 10 K with each hour of testing).

Accelerated Degradation Analysis

The ALTA degradation analysis folio allows you to analyze degradation data obtained under accelerated stress levels in order to estimate when failure would occur under the accelerated conditions. Now in Version 8, the software also automatically performs accelerated life data analysis on the extrapolated failure times and allows you to obtain calculated results and plots for the use stress conditions directly within the same folio — no need to transfer or link to another analysis folio!

Accelerated Life Test Planning

The ALTA Test Plan utility implements the complex mathematical models required to design an effective accelerated life test plan. The tool offers a choice of one-stress or two-stress test planning methods. Based on your inputs about the expected failure behavior and available test time, the software recommends the stress levels to be tested and the most effective allocation of available test units to each level.