Taxonomy of wrinkles

Abstract

Taxonomy is the practice and science of classification. Without taxonomy, everything is lumped into one pot and confusion prevails. All wrinkled or buckled webs should not be filed under one category. Just as birds are observed and divided by what they look like and where they appear wrinkled webs have characteristic visual clues and common causes. Much of taxonomy in other fields is justified by the ability to separate the good from the bad, such as managing invasive species. For wrinkles, all forms are considered invasive and undesirable, but taxonomy will help to understand the causes of specific wrinkles and help point the direction of either eliminating the cause or finding an appropriate remedy based on the cause.

This paper outlines one approach to categorize wrinkling causes based on over twenty year's observations and the contributions of other experts of wrinkle prevention and elimination. This taxonomy divides buckled webs by three locations: in spans, on rollers, and within rolls. Buckled webs on rollers, the narrow definition of wrinkling, are divided into four mechanisms. Shear wrinkles, as defined by the work of Gehlbach, Good, and Kedl. Tracking wrinkles (or principle stress wrinkles) where the left and right sides of a web track toward the web's centerline (or other lane) with enough crossweb compressive stress to induce buckling. Constrained expansion wrinkles, such as develops in on-roller conduction or radiant heating or hygroscopic expansion in the outer wraps of a paper roll. Accumulation wrinkles, the only wrinkle species forming dominantly crossweb creases, where the compressive stresses build up in the machine direction. This paper includes over 50 examples of where these wrinkle mechanisms occurs despite our best efforts.