CBEMS155/MAE156 Winter Session 10wk 2014

University of California, Irvine Chemical Engineering and Materials Science

Mechanical and Aerospace Engineering

CBEMS155/MAE156 Khinlay Maung Winter Session 10wk 2014 Due: Tuesday, August 19th

Problem #3 (Project-Course Outcome #6)

You are the leader of a group in a small company whose has only one manager. Your group is responsible for problems related to mechanical properties and analysis. The manager sends you a short project to determine the allowable pressure pallow in a spherical tank under the condition that the normal strain at the outside surface of the tank is not to exceed 0.0001. The statement of the project is the following. A compressed-air tank having an inner diameter of 18 inches and a wall thickness of 0.25 inch is formed by welding two hemispheres of a steel alloy that your company produces.

You start collecting information about the characteristic of the steel alloy and the weld. The information you and your group manage to collect is the following:

• The yield tensile strength of the steel alloy in tension is 32 ksi. • The yield shear strength of the steel alloy in shear is 12 ksi. • The yield tensile strength of the weld is 32.5 ksi • The modulus of elasticity, E, for the steel alloy is 29x106 psi and Poisson’s ratio is 0.29. • The factor of safety against failure in tension and shear for the steel alloy is 2. • The factor of safety against failure in tension for the weld is 2.5.

(1) What are the criteria that you and your group need to formulate to detemine pallow? (2) What is the method that you and your group use to solve the problem? (3) What is the value of pallow that you report to the manager and that according to your

group’s calculations allows the spherical tank to be used without failure?

In providing the manager with the answer, you need to write a cover letter along with your report explaining how your group handles the project.