Category Archives: Mechanics of Materials

This Wall Pressure Vessels

 

 Model Description These physical models demonstrate basic principles underlying the behavior of thin-walled pressure vessels (TWPVs).  Two models of TWPVs are used to explain forces inside of TWPVs.  This demonstration should take 10-15 minutes. Engineering Principle The basic derivation for TWPV behavior (when ) states that for a cylindrical pressure vessel: where the hoop stress […]

This Walled Pressure Vessels – Hot Dogs!

 

 Model Description This is a simple demonstration of the basic principals underlying the behavior of thin-walled pressure vessels (TWPVs).  A hot dog is used to show that hoop stresses are twice as high as longitudinal stresses in cylindrical pressure vessels and failure occurs along the length of the hot dog.  The failure that occurs in […]

Thermal Expansion

 

 Model Description This physical model demonstrates thermal expansion for different metals. This demonstration should take 10-15 minutes. Engineering Principle When materials, especially metals, are exposed to heat, they expand at different rates. The reverse is also true in that cold temperatures tend to cause material contraction. The amount of expansion/contraction may be small, but if […]

The Big Book of Shear

 

 Model Description Students often have difficulty with shear and stress/strain transformation.  To give a quick demonstration of pure shear and stress transformation, blocks are drawn on the side of a BIG book to show the effects of shear and transformation of axes. This demonstration should take 3-5 minutes. Engineering Principle Shear occurs when parallel planes […]

Shear Demonstrator

 

 Model Description These demonstrations show the effects of shear within rectangular members. This demonstration should take 10-15 minutes. Engineering Principle When a load perpendicular to the longitudinal axis is applied to a beam, the force is transferred through the beam through shear. With the help of these two demonstrations, the students will better understand how […]

Rubber Shapes

 

 Model Description These physical models easily and quickly demonstrate the behavior of varying cross-sectional shapes to varying loading conditions. When the instructor passes the rubber shapes around during class, students personally experience the associated behavior and quickly catalog for themselves when shapes are best used. Applying vertical, horizontal, and circumferential lines along the length allow […]

Paper Stress Concentrations

 

 Model Description This is a simple demonstration of the basic principles and behavior underlying stress concentrations.  Stresses at points of load application can be much larger than the average stress in a member. The same is true when a member contains a discontinuity. Paper members with the same mid-span width are used to demonstrate the […]

Foam Beam

 

 Model Description This simple demonstration depicts how moments (and forces) result in bending of a beam and how the deformation is related to the assumptions associated with elastic beam behavior. A foam beam with vertical lines (black lines) and a horizontal line drawn along the neutral axis (red line) for a rectangular beam is used […]

Elastic vs Plastic Deformation

 

 Model Description This is a simple demonstration of the basic principles underlying the elastic and plastic behavior of materials subjected to an axial load.  The demonstration can also be used to show the highlight the elastic and plastic portions of stress-strain curves. This demonstration should take 8-10 minutes. Engineering Principle The basic definitions for stress, […]

Design of Axial Members

 

 Model Description This is a simple demonstration to introduce the basic principles of experimentation, analysis, and design in reference to axially loaded members. Copper wire is used to lift an object of known weight. In order to determine the minimum number of copper wire strands required to lift the load, students perform experiments, analysis, and […]