Mode I DCB Fixture Using Drill Jig and Rotating Pin Blocks
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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 approximately a week.
Innovation Solution
A drill jig is used to precisely locate and drill holes in the DCB specimens, eliminating the need for hand sanding and volatile solvent cleaning, 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 specimen can be assembled for testing, but the preparation time increases to approximately a week and costs increase significantly
Solution Approach 1:
The patent extracts and eliminates the adhesive bonding process entirely from the specimen preparation. Instead of bonding hinges to the DCB specimen, the invention uses a drilling method that creates holes through the specimen, allowing pins to be inserted directly without any adhesive, masking, or bonding jig requirements.
Solution Approach 2:
The patent replaces the mechanical adhesive bonding system with a mechanical drilling and pin insertion system. The drilling method creates precise holes that accommodate pins, eliminating the need for adhesive application, curing time, and bonding fixtures while achieving reliable mechanical connection.
2Reliability
If traditional adhesive bonding method is used to attach hinges to DCB specimens, then the specimen can be assembled for testing, but the manufacturing complexity and costs increase due to multiple preparation steps
Solution Approach 1:
The patent extracts and eliminates the adhesive bonding process entirely from the specimen preparation. Instead of bonding hinges to the DCB specimen, the invention uses a drilling method that creates holes through the specimen, allowing pins to be inserted directly without any adhesive, masking, or bonding jig requirements.
Solution Approach 2:
The patent replaces the mechanical adhesive bonding system with a mechanical drilling and pin insertion system. The drilling method creates precise holes that accommodate pins, eliminating the need for adhesive application, curing time, and bonding fixtures while achieving reliable mechanical connection.
3Ease of operation
If traditional external load application method with hinges is used, then the DCB test can be performed, but potential fracture points are introduced at the bond lines
Solution Approach 1:
The patent nests the load application mechanism inside the specimen structure. Instead of attaching external hinges to the outside surfaces, the drilling method creates holes within the specimen thickness, and pins are inserted through these holes, nesting the rotation mechanism inside the specimen body rather than on the exterior.
Solution Approach 2:
The patent extracts the hinges from the external bonding system and replaces them with internal pin mechanisms created through drilling. This eliminates the bond lines between hinges and specimen, removing the fracture points that would occur at the adhesive interfaces during loading.
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.