Mode I fracture testing fixture

Patent metadata

Field	Value
Publication number	US-11298754-B1
Application number	US-202016878731-A
Country	US
Kind code	B1
Filing date	May 20, 2020
Priority date	May 20, 2020
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

An apparatus and method for preparing Double Cantilever Beam (DCB) specimens are disclosed as an apparatus and method for conducting Mode I fracture resistance testing using the DCB specimens. In a first embodiment, a drill jig is used to locate the DCB specimen and guide a drilling process during creation of at least one through-hole in the DCB specimen. The drilling process may employ a traditional drill and drill bit, a laser drill, or a water jet. In another embodiment, a set of rotating pin blocks, each with a full-round or a half-round specimen pin at one end and a hanger full-round pin at the other end, engage the DCB specimen and facilitate the internal application of a fracturing load to the DCB specimen for the Mode I fracture resistance test. The present invention may significantly reduce the time and materials needed to prepare and test a DCB specimen.

First claim

The invention claimed is:

1. A method for conducting a Double Cantilever Beam (DCB) test comprising the steps of:
providing upper and lower pin block hangers;
providing at least two rotating pin blocks, each of the at least two rotating pin blocks including a specimen half-round pin and a hanger full-round pin, each specimen half-round pin substantially parallel to a corresponding hanger full-round pin;
providing a DCB specimen having one hole therethrough;
rotationally mechanically coupling each hanger full-round pin of each of the at least two rotating pin blocks to a corresponding one of the upper and lower pin block hangers;
rotationally mechanically coupling each specimen half-round pin of each of the at least two rotating pin blocks to the DCB specimen via the one hole in the DCB specimen;
applying a fracturing load to the DCB specimen via the at least two rotating pin blocks and the upper and lower pin block hangers;
recording the applied fracturing load as a function of time;
recording an interlaminar delamination crack length as a function of time; and
calculating the strain energy release rate of the DCB specimen based upon the recorded applied fracturing load and the recorded interlaminar delamination crack length.

2. The method of claim 1 , further comprising the step of performing fractography.

3. The method of claim 1 , wherein a flat surface of a specimen half-round pin of a first of the at least two rotating pin blocks is adapted to face a corresponding flat surface of an opposing specimen half-round pin of a second of the at least two rotating pin blocks.

4. The method of claim 1 ,
wherein the at least two rotating pin blocks includes four rotating pin blocks;
wherein an end of a specimen half-round pin or a hanger full-round pin of each of the four rotating pin blocks includes a portion of an interlocking feature; and
wherein the portion of the interlocking feature of a first of the four rotating pin blocks is adapted to fixedly mechanical couple with the portion of the interlocking feature of a second of the four rotating pin blocks.

5. The method of claim 4 , wherein the interlocking feature includes one of a rod and corresponding recess, a tab and corresponding slot, and meshing teeth.

6. The method of claim 1 , wherein each specimen half-round pin and each hanger full-round pin of each of the at least two rotating pin blocks is fixedly or removably attached to a body of a corresponding one of the at least two rotating pin blocks.

7. The method of claim 1 ,
further comprising the step of preparing the DCB specimen, the step of preparing the DCB specimen including the steps of:
locating the DCB specimen within a drill jig;
aligning a drill with the DCB specimen at a predetermined position,
the predetermined position being aligned with a laminar interface between first and second joined adherend layers that form the DCB specimen;

drilling the one hole through the DCB specimen at the predetermined position.

Assignees

• Nat Tech & Eng Solutions Sandia Llc

Inventors

• Briggs Timothy

Classifications

• G01N2203/04

  Chucks, fixtures, jaws, holders or anvils · CPC title

• G01N2203/0091

  Peeling or tearing · CPC title

• G01N3/24

  by applying steady shearing forces (G01N3/26, G01N3/28 take precedence) · CPC title

• B23B2247/12

  Drilling jigs with means to affix the jig to the workpiece · CPC title

• B23B47/28 Primary

  Drill jigs for workpieces (equipment for setting or guiding the drill B23B49/00) · CPC title