US 5,705,752 AGranted

Rubber substrate shear lap-joint testing fixture and method

AssigneeThe Aerospace Corporation

InventorsDick J. Chang, William D. Hanna

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Abstract

A back-to-back, single lap-joint test fixture and method provides for uniform shear strength determination in a lap-joint area at an adhesive bond plane between a low-modulus rubber-like elastic material substrate and a stiff panel both defining a single lap-joint specimen, two of which are disposed back-to-back with the rubber substrates being constrained from lateral deformation by respective aluminum housings each having a load-transferring lip pushing upon a substrate also being pulled by load transferring dowel pins pulling upon the rubber substrate while with a restraining clamp that restrains transverse movement of the housing and rubber substrate all so as to produce only shear-type failures based on the near-incompressible nature of the rubber materials in the two back-to-back single lap-joint specimens.

Claims12

Dependent claims

A fixture for testing the shear strength of a lap-joint by an external load, the fixture comprising

a specimen in rectangular proportions having a substrate and a panel both bonded horizontally together by an adhesive forming a bond plane therebetween, the substrate is separated into a right substrate portion and a left substrate portion by a substrate groove, the panel is separated into a right panel portion and a left panel portion by a panel groove, the bond plane between the substrate groove and the panel groove defining the lap-joint,
a housing comprising a downwardly extending housing flange defining a housing cavity into which is disposed the right substrate portion comprising a front edge and two side edges, the downwardly extending housing flange extends down into the substrate groove to thereat buttress the front edge of the right substrate portion, the downwardly extending housing flange further buttresses the side edges of the right substrate portion, so as to constrain the right substrate portion from deformation when pulled by the load from the left panel portion during testing so as to isolate shear tension in the lap-joint,
right connecting means for connecting the right substrate and right panel portions and housing to the load, and
left connecting means for connecting the left substrate and left panel portions to the load, the load pulls the left connecting means from the right connecting means during testing.

1 more element

A fixture for testing the shear strength of a top lap-joint and bottom lap-joint by an external load, the fixture comprising

a top specimen in rectangular proportions having a top substrate and a top panel both bonded horizontally together by an adhesive forming a top bond plane therebetween, the top substrate is separated into a top right substrate portion and a top left substrate portion by a top substrate groove, the top panel is separated into a top right panel portion and a top left panel portion by a top panel groove, the bond plane between the top substrate groove and the top panel groove defining the top lap-joint,
a bottom specimen in rectangular proportions having a bottom substrate and a bottom panel both bonded horizontally together by the adhesive forming bottom bond plane therebetween, the bottom substrate is separated into a bottom right substrate portion and a bottom left substrate portion by a bottom substrate groove, the bottom panel is separated into a bottom right panel portion and a bottom left panel portion by a bottom panel groove, the bottom bond plane between the bottom substrate groove and the bottom panel groove defining a bottom lap-joint, the top panel and bottom panel buttress each other with the top lap-joint and bottom lap-joint in vertical alignment,
a top housing comprising a downwardly extending top housing flange defining a top housing cavity into which is disposed the top right substrate portion comprising a front edge and two side edges, the downwardly extending top housing flange extends down into the top substrate groove to thereat buttress the front edge of the top right substrate portion, the downwardly extending top housing flange further buttresses the side edges of the top right substrate portion, so as to constrain the top right substrate portion from deformation when pulled by the load from the top left panel portion during testing so as to isolate shear tension in the top lap-joint,
a bottom housing comprising an upwardly extending bottom housing flange defining a bottom housing cavity into which is disposed the bottom right substrate comprising a front edge and two side edges, the upwardly extending bottom housing flange extends up into the bottom substrate groove to thereat buttress the front edge of the bottom right substrate, the downwardly extending bottom housing flange further buttresses the side edges of the bottom right substrate, so as to constrain the bottom right substrate portion from deformation when pulled by the load from the bottom left panel portion during testing so as to isolate shear tension in the bottom lap-joint,
right connecting means for connecting the right substrate and right panel portions and top and bottom housing to the load, and,
left connecting means for connecting the left substrate and panel portions to the load, the load pulls the left connecting means from the right connecting means during testing.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/609,409Filed 1 Mar 1996
Granted: 6 Jan 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 19/04
Investigating materials by mechanical methods: measuring adhesive force between materials, e.g. of sealing tape, of coating
G01N 3/24
Investigating strength properties of solid materials by application of mechanical stress: by applying steady shearing forces
G01N 2203/0405
Chucks, fixtures, jaws, holders or anvils: features allowing alignment between specimen and chucks
G01N
Investigating or analysing materials by determining their chemical or physical properties

Family

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