A Boltless Structure with Fibers that Suppress Crack Propagation

Abstract/Technology Overview

This invention encompasses a new crack arrestor technology that consists of adhesive layers and bridging fibre layers arranged in a specific configuration between that suppresses crack propagation between two adherend substrates. With this crack arrestor, the apparent fracture toughness may be increased by more than five-folds at the arrestor position. This technology is particularly suitable for use in complex structures such as housing, aircrafts, ships, automotive and so forth.

Technology Features, Specifications and Advantages

The crack arrestor consists of the bonding the two 0° composite layer between the two adherend substrate in an interlocking 'x' shaped configuration (Figure 2), with the 90° reinforcement composite layer inserted between the interlocking members of the two earlier composite layer to form a final configuration illustrated in Figure 3. Appropriate adhesive is used to bond the various surfaces (i.e. interlocking composite to adherend substrate; interlocking composite to interlocking composite; interlocking composite to reinforcing composite). 

As a crack in the adherend substrate propagates towards the arrestor, the crack is robustly entrapped in the arrestor by virtue of the surface ply-drop of the adherends. As the crack approaches the arrestor, the 0° interlocking composite layers bridges the crack and suppresses further crack opening as seen in Figure 4. The 90° layer acts as a reinforcement and prevents the interlocking layer from further peeling off as the crack propagates, effectively increasing the fracture toughness.

Potential Applications

This technology is especially suitable for any large/complex structures made of Carbon Fibre reinforced plastics (CFRP). For instance, in an aircraft like the Boeing 787 where the fuselage is made of difficult-to-machine CFRP, the drilling and installation of the many bolts present is difficult and time consuming. Adopters of the new crack arrestor technology can reduce the work required. In addition, weight, cost and air resistance reductions may be achieved.

Customer Benefit

  • This technology allows users to implement a streamlined joint design without the use of bolts that are difficult and time consuming to install. Furthermore, it has a crack propagation suppression characteristics that conventional bolted designs lack.
  • The crack arrestor also improves the fracture toughness of conventional adhesive bonded joints.
  • In addition, weight, cost and air resistance reductions may be achieved with the reduced bolts used.

Contact Person

Satoshi Konno


IP Bridge, Inc.

Technology Category
  • Green Building
  • Manufacturing
  • Joining
  • Materials
  • Composites
Technology Status
  • Available for Licensing
Technology Readiness Level
  • TRL 5

composite, joint, crack, arrestor, CFRP, adhesive, bolt, fastener