David H. Johnson, Assoc. Prof. of Engr., Samples

David H. Johnson, P.E., Associate Professor of Engineering

Sample work done (Updated 01/24/06)

During a "simple" clothes dryer motor replacement job, I smacked the face of the fan with my hand to drive it down onto the motor shaft and split the fan into 2 pieces. My son and I observed a significant stress concentration exists in the D-shaped hole, off-center from the motor shaft and an ANSYS-Workbench model showed that for the loading applied and the support from the tight shaft fit, a crack would originate at one of the corners on the D-shaped hole.

Piezoelectric transducer (17 kB gif image)

A 2D, axisymmetric ANSYS model of a piezo. transducer assembly was developed for modal, harmonic response, and general (non-linear) transient analysis to simulate a core-drill device designed for a Mars probe mission in 2003. (Published at the 9th International ANSYS Conference, August, 2000)

3D Nut & Bolt Assembly (27 kB gif image)

A 3D, nonlinear (plasticity + contact + friction) model was developed to permit studies to verify 2D, axisymmetric models, of the effects of turning the nut, and thread stress concentration. (Published at the 9th International ANSYS Conference, August, 2000)

Channel Buckling Test and FEA Model (157 kB jpg image)

A nonlinear buckling FEA analysis of a simply supported beam with a center load shows very good agreement with the physical test. This test was designed to produce lateral buckling (the ripple in the top flange). The ANSYS shell element model is 1/4 symmetry of the two channel physical test.

Powdered Metal Press Animation

This animation (avi) file is 1.66 MB. It shows a simulation of a pressing operation model for a powdered metal part. The front punch and back punch move into the stationary die.

Steering Knuckle (31 kB gif image)

This is an auto industry steering knuckle model using the Pro/ENGINEER software from Parametric Technology Corporation. This model was presented at the Society for Experimental Mechanics conference on Integration of FEA and Structural Testing with Rapid Prototyping in Dearborn, MI on 10/31/95. Work done by Prof. D. E. Roth and Prof. D. H. Johnson.

Steering Knuckle FEA Model (18 kB gif image)

This is the same auto industry steering knuckle modeled for a finite element analysis using the ANSYS software. This .gif file shows the loads and constraints imposed on the structure. Work done by Prof. D. E. Roth and Prof. D. H. Johnson.

Steering Knuckle FEA Model, First Principal Stress (20 kB gif image)

This steering knuckle model display shows the finite element analysis results using the ANSYS software. This .gif file shows the tensile stress (1st principal stress, in psi) on the structure. Work done by Prof. D. E. Roth and Prof. D. H. Johnson.

Steering Knuckle FEA Model, First Principal Stress, Another View (19 kB gif image)

This steering knuckle model display shows the finite element analysis results using the ANSYS software. This .gif file shows the tensile stress (1st principal stress, in psi) on the structure from a different viewpoint. Work done by Prof. D. E. Roth and Prof. D. H. Johnson.

Finned Aluminum Heat Sink (23 kB gif image)

This heat sink is used to dissipate heat in electronic devices. This .gif file shows the quarter-symmetry finite element model used for an ANSYS steady-state, heat transfer analysis.

Finned Aluminum Heat Sink, Temperature (24 kB gif image)

This .gif file shows the quarter-symmetry finite element model results (temperature distribution) of an ANSYS steady-state, heat transfer analysis.

Finned Aluminum Heat Sink, Computational Fluid Dynamics (CFD) (29 kB gif image)

This .gif file shows the quarter-symmetry finite element model used for an ANSYS/FLOTRAN CFD analysis of air flow above the heat sink. The plot shows velocity vectors in the air.

Residential Fuel Oil Tank (16 kB gif image)

This model was used in my first course in FEA Applications to introduce thin shell finite elements. This .gif file shows the quarter-symmetry finite element model used for an ANSYS static analysis of the tank when filled with oil.

Residential Fuel Oil Tank, Boundary Conditions (13 kB gif image)

This .gif file shows the symmetry constraints imposed on the model for an ANSYS static analysis of the tank when filled with oil.

Residential Fuel Oil Tank, Equivalent Stress (15 kB gif image)

This .gif file shows the equivalent (vonMises) stress on the model for an ANSYS static analysis of the tank when filled with oil.

Vibration of a Compressor Fan (11 kB gif image)

This model was used in my first course in FEA DYNAMIC Applications to introduce the concept of stress stiffening. This .gif file shows the first mode of vibration for a fan, stiffened by the centrifugal forces induced by a 3000 RPM constant rotational speed.