Product Stability -- Table

A family enters a fast food restaurant. While the parents go to the counter to place their order, their child walks over to a tall pedestal table containing condiments. The child is too short to see what is on top of the table. He reaches up and grips the edge of the table top and attempts to pull himself up. The table topples. The child falls and the edge of the table top strikes the child's face.

HF Investigation: Age, gender, height and weight of the child; the dimensions and weight of the table; amount of force required to tilt table.

HF Analysis: It was observed that the table's two pedestal bases were so oriented that their four feet provided the minimum possible base of support along the table's major axes. If the pedestals were rotated 45 degrees, the table would have been significantly more stable in the direction most vulnerable to tipping.

It was not clear, however, whether such a change would have prevented the accident.

The table and child were modeled using Working Model by Knowledge Revolution. Working Model 2.0 simulates gravity, mass, velocity, and other physical parameters in a two dimensional universe. Two copies of the model were generated. A single modification was made to the second copy of the model -- the table's base of support was increased to reflect a 45 degree change in pedestal orientation.

Under exactly the same conditions of load, the table with the larger base of support did not tip over while the one with the smaller base toppled and struck the child's face.
Opinion: The table's two pedestal bases were improperly oriented when secured to the bottom of the table. If they had been properly oriented then, more likely than not, the table would not have tipped over onto the child.
2934 Steamboat Island NW
Olympia, WA 98502
www.gdsloan.com
(360) 866-1768 voice
(360) 866-1810 fax
gdsloan@aol.com
This material may be used freely provided you
reference this source:
G. David Sloan, Inc., 1999, www.gdsloan.com, Olympia, WA, USA
Site design by Alex Gheorghiu, Chuck Mathison & Pam Johnson
Olympia, WA