This packet is intended for presentation in Strength of Materials I shortly after the thin-walled pressure vessel equations are developed. It gives an overview of several concepts that lead to safe design. Specifically, it introduces the students to safety issues in the design of pressure vessels. The ill-fated Comet aircraft debacle is used to introduce fracture mechanics and the importance of considering fracture mechanics concepts, such as fracture toughness, in design. Proof testing, "yield before break", and "leak before break" concepts are discussed. The 1988 Aloha Airplane accident is used to introduce fail-safe design. . Because of the "overview level" of discussion, it is ideal for presentation in conjunction with review for an examination or some other period when the students can sit back and absorb concepts instead of focusing on equations.
Time for presentation is estimated as 30-60 minutes.
Objectives:
1. To introduce the students to safety issues in the design of pressure vessels.
2. To give an overview of fracture mechanics, fracture toughness, proof testing, "yield before break", "leak before break", and fail-safe design.
This packet includes the following items:
· Lecture material for the instructor
· Overheads for use during the lecture
· Handouts for the students
· Homework problem
Preview the Lecture material, Overheads, and Handouts
Download the Homework Problem in a printable Adobe Acrobat Format (pdf).
Download the PowerPoint Presentation and notes
Homework problem solutions, exam problems, and exam solutions are available to qualified recipients. Send an email with request information to Dr. Donald Bloswick.
1. What is the fundamental difference between the continuum mechanics and the fracture mechanics models? Which model would be more likely to compel a need for inspection of a fielded system, and why?
2. What is the purpose of a pressure relief valve?
3. What is the fracture toughness of a material?
4. What is the idea behind the "yield before break" concept in pressure vessel design?
5. What is the idea behind the "leak before break" concept in pressure vessel design?
6. What is fail-safe design?