Improving Reliability by Reducing Tolerance Stack-Up Failures

Abstract

Excalibur is the Army's 155-mm guided bullet for howitzers. Once fielded, Excalibur is expected to have a reliability of 90%. This paper describes a method to predict the reliability of the locking mechanism in the fuze safe and arm device. Hand calculations showed that a locking failure could occur if several dimensions were machined close to a tolerance limit in the same device. The probability of a locking failure was estimated using Monte Carlo simulations and a First Order Probability method. The governing equation was a function of about a dozen other equations and 21 variables. A probability distribution function described each variable's nominal dimension and tolerance. Both Monte Carlo simulations and First Order Probability methods predicted fewer than 35 failures in a million devices. Output also included a ranking of dimensions and tolerances and their relative effect on reliability.

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 2005
Accession Number
ADA443508

Entities

People

  • J. A. Cordes
  • M. R. Kahlessi
  • M. Worthington
  • S. Recchia

Organizations

  • United States Army Armament Research, Development and Engineering Center

Tags

Communities of Interest

  • Human Systems
  • Space
  • Weapons Technologies

DTIC Thesaurus Topics

  • Accuracy
  • Boundaries
  • Case Studies
  • Data Science
  • Distribution Functions
  • Engineering
  • Equations
  • Governments
  • Information Science
  • Monte Carlo Method
  • Probability
  • Probability Distributions
  • Projectiles
  • Reliability
  • Simulations
  • Standards
  • Weapons

Fields of Study

  • Engineering

Readers

  • Logistics and Supply Chain Management.
  • Statistical inference.
  • Structural Health Monitoring of Composite Structures.