Design for Static Strength
Robert B. Wilcox, P.E.
This course covers
the design of parts for static strength. Safety factors, material properties,
elementary heat treatment, stress concentrations, and ductile vs. brittle materials
will be discussed. Various static failure theories will be presented, focusing
on Von Mises-Hencky (distortion energy) theory for ductile materials, and the
modified Mohr theory for brittle materials. Application of FEA results to static
failure theories will be covered. The course is intended as either a review
or a primer in the field of designing for static strength. It is assumed the
student has a working knowledge of basic stress analysis. Fatigue and fracture
mechanics will not be covered.
The course includes
a multiple-choice quiz at the end, which is designed to enhance the understanding
of the course materials.
At the conclusion of this course, the student will:
This course is intended for engineers or architects who want to review the basics of static design theory, and learn how to apply results from either manual or FEA in static failure theory.
Benefit to Attendees
The attendee will
understand basic static strength design theory.
methods have changed, but much of historical static design theory remains valid
today. FEA results are frequently misapplied or judged to be overly conservative
due to misunderstanding of stress concentration effects and static strength
design theory. A solid understanding of the basic material constants and static
design theory is essential for making sound design decisions based on modern
computer based method of stress analysis. Understanding the differences between
ductile and brittle materials and how they respond to stress concentrations
is important in static design and is also frequently misunderstood. Manual stress
calculation techniques are also essential for "reality checks" of
computed results. This course helps tie together the stress analysis tools of
today with basic manually applied classical static design theories.
Course Content The
course content is in a PDF file (500 KB) Design
for Static Strength.
The course content is in a PDF file (500 KB) Design for Static Strength.Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.
Material Properties and Testing
Safety Factors and Allowable Stress
Combined Stress Failure Theories
Von Mises-Hencky (Distortion Energy) Theory
Maximum Shear Stress Theory
Modified Mohr's Theory
Maximum Normal Stress Theory
Combined Stress Failure Theory Examples
Application of FEA Stresses
A concise treatment of elementary design for static strength concepts, which will assist designers in the task of designing parts and members for static applications.
For additional technical information related to this subject, please visit the following websites or web pages:
Mohr's Circle Calculator: http://www.aoe.vt.edu/~jing/MohrCircle.html
Stress Concentration calculator: http://www.fatiguecalculator.com/finders/findkt.htm
theory and safety factor calculator (calculator is a script near the end of
the page… http://www.mech.uwa.edu.au/DANotes/SSS/failure/theories.html
Good information on corrosion: http://www.corrosionsource.com/