DCB Fracture Test Fixture With Drill Jig and Internal Pin Loading
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Solution Overview
Problem
The current method for preparing Double Cantilever Beam (DCB) specimens is time-intensive and expensive, requiring hand sanding, volatile solvent cleaning, and extensive adhesive application, which prolongs the specimen preparation time to several days.
Innovation Solution
A drill jig is used to precisely locate and drill holes in the DCB specimens, eliminating the need for hand sanding and adhesive application, and a rotating pin block system applies the fracturing load internally, reducing preparation time and eliminating potential fracture points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional adhesive bonding method is used to attach hinges to DCB specimens, then the bonding strength is sufficient, but the preparation time increases to several days and costs increase
Solution Approach 1:
The patent extracts and eliminates the adhesive bonding process entirely by replacing it with a mechanical drilling and pinning system. Holes are drilled through the DCB specimen and hinges are mechanically secured with pins, completely removing the time-consuming adhesive application, curing, and cleanup operations while maintaining secure attachment.
Solution Approach 2:
The patent replaces the chemical bonding system (adhesive) with a mechanical bonding system (drilled holes and pins). This substitution eliminates the need for volatile solvents, adhesive mixing, and extended curing times, reducing preparation from several days to hours while achieving equivalent or superior attachment reliability.
2Manufacturing precision
If hand sanding and solvent cleaning are performed on bonding surfaces, then surface preparation quality is sufficient for adhesive bonding, but the process becomes extremely time-intensive
Solution Approach 1:
The patent removes the entire surface preparation process (hand sanding, solvent cleaning, masking) by eliminating adhesive bonding. Instead, holes are drilled at precise locations using a jig, and hinges are mechanically attached, completely bypassing the need for surface preparation and thereby dramatically improving productivity.
Solution Approach 2:
The patent uses a disposable or easily replaceable drilling jig that ensures precise hole placement without requiring repeated surface preparation. The jig can be quickly repositioned or replaced between specimens, eliminating the time-intensive repetitive surface preparation process while maintaining manufacturing precision.
3Reliability
If adhesive is applied by hand to bonding faces, then adhesive coverage is sufficient, but the process requires extensive manual labor and time
Solution Approach 1:
The patent replaces the manual adhesive application process with a mechanical drilling and pinning system. Holes are drilled through both the DCB specimen and hinge using a guided jig, and pins are inserted to secure the hinge, completely eliminating hand adhesive application and associated complexity.
Solution Approach 2:
The drilling jig automatically positions and guides the drilling operation, eliminating the need for manual adhesive application and positioning. The system self-aligns through the jig's guide holes, ensuring consistent and reliable hole placement without requiring skilled manual intervention.
4Force
If bonded hinges are used to apply load during DCB testing, then the load application is effective, but the bond line becomes a potential fracture point
Solution Approach 1:
The patent extracts and eliminates the bond line from the load path by replacing bonded hinges with mechanically pinned hinges. The pins pass through holes in the DCB specimen and hinge, creating a direct mechanical connection that bypasses the adhesive bond line, thereby eliminating it as a potential fracture point while maintaining effective load application.
5Manufacturing precision
If extensive adhesive cleanup is performed after bonding, then adhesive spill-out is removed, but additional time and complexity are added to the process
Solution Approach 1:
The patent eliminates the cleanup step entirely by removing the adhesive application process. Since hinges are mechanically pinned rather than bonded with adhesive, there is no adhesive spill-out to clean up, thereby eliminating this time-consuming step while maintaining specimen cleanliness.
Data Source
AI summary
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.