# 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 […]

# 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 […]

# 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 […]

# Axial Strain

Model Description This is a simple demonstration of the basic principles underlying the behavior of materials subjected to an axial load.  The demonstration can also be used to show the usefulness of stress-strain curves versus load-deformation curves.  This demonstration should take 10 minutes. Engineering Principle The basic definitions for deformation and strain: where the axial […]

# A Strainge Transformation

Model Description A thin rectangular sheet of rubber material is subject to an axial load.  Stress blocks are painted or drawn on the rubber material.  The stress blocks are oriented on a transverse plane (black square) and on a plane 45° from the transverse plane (red square). Students have previously learned that only normal stress […]

# Creepy Plastic

Model Description This is a simple demonstration to illustrate initial deformation, primary creep and secondary creep of a material subjected to a constant load over time.  Students can observe a phenomenon over a few days that often takes years to complete.  Students can compute the steady state creep rate and gain an appreciation for the […]

# From Strain to Weight … of an engine block!

OVERVIEW This exercise uses an engine hoist, an engine block, and an aluminum “dog bone” to measure the weight of the engine block. The dog bone has strain gages attached. With the measured strain, students calculate the associated weight. PRINCIPLES Reinforces the relationship between strain and stress; and between stress and force. This exercise also […]

# Balloons!!: A demonstration of thin-walled pressure vessels

Overview This is a simple demonstration of the basic principals underlying the behavior of thin-walled pressure vessels (TWPVs).  A balloon or balloons are used to show that hoop stresses are twice as high as longitudinal stresses in cylindrical pressure vessels. Principle The basic derivation for TWPV behavior states that for a cylindrical pressure vessel   […]