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in strength of materials, a localized compressive stress, accompanied, as a rule, by permanent deformation (pressing down) of the material. Crumpling occurs in joints (bolted, riveted, key) in locations of structural supports, and in contact zones of compressed components.

The magnitude of crumpling stress in structures is usually kept below the allowable crumpling stress. This allowable stress is determined by the character of the surfaces in contact, the properties of the structural material, and the orientation of this material with respect to applied loads (for instance, with wood, parallel or perpendicular to the grain). Various design features aimed at reducing crumpling stresses and, more important, permanent deformation distribute the compressive stress over a large area with the aid of, for example, washers, liners, and pads. One of the most effective means for reducing deformation is the use of special inserts and fillers in the contact zones made of materials that are stronger than the structural material.


References in periodicals archive ?
For example, we can tune the graphene from being transparent to opaque by crumpling it, and tune it back by unfolding it," said Jianfeng Zang, a postdoctoral fellow in Zhao's group and the first author of the paper.
The crumpling and unfolding of graphene allows large deformation of the artificial muscle," Zang said.
Crumpling a sheet of paper into a tight ball causes some regions to become strongly creased, creating a network of narrow ridges and sharp peaks.
To investigate the energy involved in crumpling, physicist Thomas A.
Because sheets of different materials-whether paper, mylar, or metal-display similar ridges, the basic crumpling process must be similar in these materials.
The ridge model of crumpling is just one ingredient in the development of an understanding of crumpling phenomena.
Houle, and their collaborators at Cornell University have been busy crumpling sheets of paper into compact balls to elucidate the collective behavior of large numbers of creases.
These studies were originally motivated by the finding that widely varying physical systems emit pulses of energy comparable to the pops and clicks generated by crumpling paper.
This finding applied equally to freshly crumpled sheets, to previously crumpled sheets that were crumpled again, and to sheets that had been initially folded into a regular, gridlike pattern of creases and smoothed out before crumpling.
As Houle also found, neither the material nor its thickness appears to make much difference to the energy distribution of the sounds produced by crumpling.
have been investigating the crumpling of polymer membranes, modeled as sheets of hard spheres tied by flexible strings to their nearest neighbors.