Floor Mat Projection Geometry for Fatigue Crack Resistance
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Solution Overview
Problem
Desk chair mats experience cracking over time due to fatigue loads, leading to reduced aesthetic appearance and functionality, as stress concentrations occur near the base of the spikes.
Innovation Solution
A floor mat design featuring a substantially planar upper surface with a lower surface having a plurality of solid projections, where the ratio of width to height is greater than 1, reducing stress concentrations and increasing the mat's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spike projections with height greater than width are used, then the mat can firmly engage with the carpet surface, but stress concentrations occur at the base of the spikes leading to cracking and reduced mat lifespan
Solution Approach 1:
The patent changes the geometric parameters of the projections by inverting the traditional dimensions: projections now have a width greater than their height (width-to-height ratio > 1:1), rather than the conventional height-to-width ratio > 1:1. This parameter inversion fundamentally alters the stress distribution pattern, moving stress concentrations away from the base to the tip of the projections, thereby preventing cracking and extending mat lifespan while maintaining firm carpet engagement
2Strength
If semi-rigid plastic material is used for the mat, then the mat can maintain structural integrity under chair loads, but fatigue loads cause cracking over time reducing aesthetic appearance and function
Solution Approach 1:
The patent modifies the geometric parameters of the projection attachments, specifically making them wider relative to their height (width-to-height ratio > 1:1). This dimensional change alters the stress distribution within the semi-rigid plastic material during fatigue loading cycles, preventing crack initiation at the projection bases while preserving the material's structural integrity under chair loads
Data Source
AI summary
A floor mat includes a plurality of projections integrally formed and extending from a lower surface. At least some of the projections have a straight axis and a cross section perpendicular to the straight axis that decreases from the base to the tip of the projection. The at least some projections have a height measured along the axis and a width corresponding to its largest dimension measured parallel to a plane of the lower surface such that the ratio of the width to the height of the projection is greater than 1.