New and Enhanced Features in Version 7
The latest upgrade to Weibull++, Version 7, provides many new and enhanced features. This page presents a summary of these features.
Enhanced Interface with Project Explorer
In Version 7, the Weibull++ interface has been enhanced to allow you to manage multiple analysis folios and related information all together in a single file. Using the intuitive "Project Explorer" approach that was first introduced in ReliaSoft's BlockSim software, Weibull++ now provides an intuitive, hierarchical (tree) view to allow you to view and manage one or many standard folios, specialized folios, plot sheets, reliability block diagrams, spreadsheet reports and/or attached documents per project. At the same time, the new work environment "stays true to its roots" so that users who are familiar with previous versions of the software will be able to enter and analyze data in much the same way as always.
Reliability Block Diagrams (RBDs) for Failure Mode Analysis
The Competing Failure Modes option has been a very popular feature among Weibull++ users. The Reliability Block Diagram (RBD) feature that has been added to Version 7 provides a huge leap forward in both flexibility and analytical power. Now, there is no limit to the number of failure modes that you can consider and each mode can be analyzed with the appropriate lifetime distribution. In addition, you can use the flexible RBD interface (patterned after the intuitive BlockSim diagram utility) to describe the reliability-wise relationships among the modes (i.e. series, parallel, k-out-of-n) and thereby model the failure behavior more accurately and realistically.
Using the exact algebraic reliability equation for the configuration that you've defined, Weibull++ provides common reliability results and plots at the click of a button. You can even consider the uncertainty of the fitted parameters of each data set to calculate confidence bounds on the overall reliability metrics!
Enhanced Warranty Analysis Module
New and enhanced features in the popular Warranty Analysis module include:
- Choice of Data Entry Form: You can choose to enter data in any of three available formats: 1) "Nevada" format with quantity shipped and quantity returned per period; 2) "Times-to-Failure" format with exact times-to-failure for returned units or 3) "Dates" format with exact manufacturing and return dates.
- Consider Subset ID: You can define and analyze data by "Subset ID" to allow for simultaneous analysis and comparison of different design iterations.
- Consider Warranty Length in Forecasts: When performing forecasting analyses, you have the option to specify the Warranty Length, which allows the analysis to take into account the possibility that failure data was not collected beyond the warranty period and/or to exclude predicted failures that fall outside the warranty period.
- Graphical Plots: You can generate a variety of graphical plots to illustrate your warranty analysis, including Reliability vs. Time, Unreliability vs. Time, pdf, Failure Rate vs. Time, Contour, Failures/Suspensions Histogram, Failures/Suspensions Pie and Failures/Suspensions Timeline. For forecasted results, an Expected Failures vs. Period plot is also available. This plot can display forecasted failures as failures per month, cumulative failures and/or as a percentage of the total population. Confidence bounds are also available.
Support for Bayesian Statistics
Although previous versions of Weibull++ have dealt exclusively with Classical statistics, Version 7 opens the door to another school of thought: Bayesian statistics. The premise of Bayesian statistics is to incorporate prior knowledge along with a given set of current observations in order to make statistical inferences. Bayesian methods have been incorporated into Weibull++ in two ways:
- Confidence Bounds: The Bayesian confidence bounds estimation method is now offered in addition to the Fisher Matrix, Likelihood Ratio and Beta Binomial methods that were already supported.
- Weibull-Bayesian Model: Now available as another lifetime distribution option, the Weibull-Bayesian model considers prior knowledge on the beta parameter of the Weibull distribution. There are many practical applications for this model, particularly when dealing with small sample sizes and some prior knowledge of the shape parameter is available.
Additional Lifetime Distributions
In addition to the Weibull-Bayesian model described above, Version 7 also provides the following additional lifetime distributions:
- Gamma
- Logistic
- Loglogistic
- Gumbel
Recurrent Event Data Analysis
In life data analysis, there are many cases where events are dependent and not identically distributed (such as repairable system data) or where the analyst is interested in modeling the number of occurrences of events over time rather than length of time prior to the first event, as in distribution analysis. Weibull++ provides both parametric and non-parametric approaches to analyze such data. The non-parametric approach is based on the well-known Mean Cumulative Function (MCF). The Weibull++ module for this type of analysis builds upon the work of Dr. Wayne Nelson, who has written extensively on the calculation and applications of MCF.
The parametric approach is based on the General Renewal Process (GRP) model, which is particularly useful in understanding the effects of the repairs on the age of a system. [See a recent Reliability Edge article for more information...]
Event Log Interface
The software now provides a specialized folio designed specifically to capture data in an event log format (commonly used in the Machine Tools and other industries). This data entry sheet captures the type of event, the date/time when the event occurred and the date/time when the system was restored to operation. The software then converts this information to time-to-failure and time-to-repair data that can be analyzed with life data analysis techniques. The folio provides a number of options to tailor the analysis to fit your particular requirements, including the ability to define shift patterns, consider unique system IDs, perform the analysis at the system, subsystem, assembly or component level, etc. You can also export the results to BlockSim for system reliability, maintainability and availability analyses.
SimuMatic
With Version 7, Weibull++ integrates the SimuMatic utility (previously distributed by ReliaSoft as freeware), that can be used to perform a large number of reliability analyses on data sets that have been created using Monte Carlo simulation. This utility can assist the analyst to a) better understand life data analysis concepts, b) experiment with the influences of sample sizes and censoring schemes on analysis methods, c) construct simulation-based confidence intervals, d) better understand the concepts behind confidence intervals and e) design reliability tests.
Risk Analysis and Probabilistic Design
You can now use the Monte Carlo simulation tool to perform relationship-based simulations. The new "User Defined" distribution feature allows you to specify an equation relating different random variables. You can then determine the joint pdf for the simulated data set. This type of simulation has many applications in probabilistic design, risk analysis, quality control, etc. For example, if the height and length of a rectangle are distributed, the area of the item is distributed as well. In order to find the distribution of the area, we can generate random height and length values based on their corresponding distributions, and then apply the equation A = H x L. A distribution can then be fitted to the resulting set of area values.
Spreadsheet-Based Customized Report Utility and Enhanced Function Wizard
The ability to build customized reports based on your Weibull++ analyses has been revised and enhanced in Version 7. You can work in a spreadsheet or report view, insert calculated results from existing analyses, and much more. The Report Template feature allows you to create customized reports that can be applied to any data set. The software also comes with an extensive array of report templates for analyses designed to determine Optimum Burn-In Time, Optimum Preventive Replacement, and much more! The Function Wizard now works more like Excel® functions, with the ability to type functions directly into cells and results that are updated automatically when the inputs change.
