Reliability of Springs: Calculating the Failure Rate and Service Life

Course Number: C-2050
Credit: 2 PDH
Subject Matter Expert: Anthony Darmiento, P.E., MSE
Price: $59.90 Purchase using Reward Tokens. Details
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Overview

In Reliability of Springs: Calculating the Failure Rate and Service Life, you'll learn ...

  • Coil spring material and nomenclature
  • Fatigue concepts of a coil spring such as the stages of fatigue crack propagation, as well as strengthening concepts like shot peening and heat treatment
  • The factors determining the failure rate and reliability of a coil spring
  • Reliability calculations for a coil spring that mechanical engineers, civil engineers, structural engineers, and chemical engineers can apply

Overview

PDHengineer Course Preview

Preview a portion of this course before purchasing it.

Credit: 2 PDH

Length: 26 pages

This course covers fundamental concepts on coil or helical springs such as the common types of spring material, spring nomenclature, and spring clash. The focus is on spring reliability including an extensive emphasis on fatigue. Various topics like stress versus number of cycles graph or curve and fatigue crack propagation are presented.

The course material is presented so that an engineer with a basic mechanical background can understand it.This foundation will then be applied to focus on calculating the failure rates based on fatigue from dynamic or fluctuating loads. Dynamic loading particularly applies to springs used for chemical, civil and mechanical engineering applications such as internal combustion engines, bridges, reservoir weirs, compressors, and medical peristaltic pumps.Buildings also utilize base isolation springs to increase their earthquake resistance.

Any discussion on failure rate will be in the context of fatigue. Hence, the fatigue failure rate calculation for springs will be explained. This calculation is based on United States Navy’s reliability research data on bolt fatigue failure.A Navy reliability handbook will be cited in this course by referencing its data tables so as to calculate a spring’s failure rate and service life.As part of the fatigue discussion, the concept of stress versus the number of cycles will be explored.

The course will demonstrate how to forecast the reliability of a coil spring based on calculating the failure rate.This will provide the probability of the spring not failing due to fatigue for any service life based on hours of operation.Understanding reliability is critical for engineers, particularly mechanical, chemical, and civil engineers. We will go through each step with estimating the service life of a spring based on applying the reliability equation authored by the reliability expert Wallodi Weibull.The service life of following springs will be estimated for a:

  • Compression coil spring within a tuned mass damper for a footbridge or overhead walkway
  • Torsion coil spring within a wave energy converter

Specific Knowledge or Skill Obtained

This course teaches the following specific knowledge and skills:

  • Reliability engineering concepts such as the Bathtub Curve, failure rate and stress versus number of cycle (S-N) graphs.
  • Review of reliability research pertaining to springs by Whirlpool’s Compressor and Cooling Solutions Unit and the US Air Force’s Reliability Analysis Center.
  • Common ways to improve the fatigue resistance of springs.
  • Calculate the failure rate for a spring based on United States Navy research.
  • Estimate the service life of a coil spring based on application of the reliability equation

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 10 questions. PDH credits are not awarded until the course is completed and quiz is passed.

Board Acceptance
This course is applicable to professional engineers in:
Alabama (P.E.) Alaska (P.E.) Arkansas (P.E.)
Delaware (P.E.) District of Columbia (P.E.) Florida (P.E. Area of Practice)
Georgia (P.E.) Idaho (P.E.) Illinois (P.E.)
Illinois (S.E.) Indiana (P.E.) Iowa (P.E.)
Kansas (P.E.) Kentucky (P.E.) Louisiana (P.E.)
Maine (P.E.) Maryland (P.E.) Michigan (P.E.)
Minnesota (P.E.) Mississippi (P.E.) Missouri (P.E.)
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PDHengineer Course Preview

Preview a portion of this course before purchasing it.

Credit: 2 PDH

Length: 26 pages

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