Composite coated jaw faces
AssigneeE. I. Du Pont de Nemours and Company
InventorDavid Ronald Ericson
Life of this patent
Estimating the term…
Abstract
Clamp or grip faces used in fiber/fabric tensile testing instruments are coated with an aramid-epoxy composite, thus allowing high-strength fiber/fabric samples to be tested with greater reproducibility at lower applied pressure and without clamp or grip face scarring.
Claims7
In a materials testing machine of the type having a pair of clamps for gripping two ends of a test specimen, power means for applying loads to said test specimen through said clamps, and control means for controlling said power means, an improvement comprising coating the faces of each of said clamps with a material comprised of an aramid-epoxy composite, wherein the composite material is applied to the clamp faces by:
- a) mixing an epoxy resin material with an appropriate catalyst material;
- b) spreading the catalyzed epoxy resin material onto a sheet of release film;
- c) placing aramid material onto the top of the catalyzed epoxy resin material, thereby allowing the epoxy material to soak through said aramid material so that substantially all air voids are removed, and thereby forming an aramid-epoxy composite;
- d) placing said clamp faces down on top of the aramid-epoxy composite, said clamp faces having been first roughened to provide good adhesion;
- e) allowing the aramid-epoxy material to cure and adhere to the clamp faces;
- f) removing the coated clamps from the release film;
- g) removing the excess aramid-epoxy material from the edges of the clamp faces;
- and
- h) roughening the coated clamp faces to provide a matte finish, so that the contact friction between the test specimen and the clamp face surface is increased.
A method of testing materials using a materials testing machine of the type having a pair of clamps for gripping two ends of a test specimen, power means for applying loads to said test specimen through said clamps, and control means for controlling said power means, an improvement comprising coating the faces of each of said clamps with a material comprised of an aramid-epoxy composite comprising the steps of:
- (a) cutting a test specimen to a size whereby its width is less than the width of the clamp faces;
- (b) optionally coating ends of the sample strip to provide for improved gripping;
- (c) placing said ends between the clamp faces;
- (d) bringing said faces together until the ends are firmly held;
- and
- (e) operating said machine so that the sample is tested until a break is recorded by the machine, wherein the power means for applying loads to the test specimen is reduced by about 10-30% as compared to grips that do not have aramid-epoxy composite coating as determined by pressure measurements.
Dependencies are inferred from the claim text.