TY  - BOOK
AU  - Li,R.
AU  - Huong,N.
AU  - Crosky,A.
AU  - Mouritz,A.P.
AU  - Kelly,D.
AU  - Chang,P.
TI  - Improving bearing performance of composite bolted joints using z-pins
KW  - A. POLYMER MATRIX COMPOSITES
KW  - Z-PINS
KW  - B. STRENGTH
KW  - B. MECHANICAL PROPERTIES
N2  - The effect of z-pins on the bearing properties and damage tolerance of composite bolted joints is experimentally studied in this paper. The region around bolt-holes in carbon/epoxy laminates was reinforced in the through-thickness direction with different volume contents and sizes of fibrous z-pins. Bearing test results show that the z-pins improved the bearing stiffness (by 7.5-9.6 percent), ultimate load (7.7-12.8 percent), failure strength (7.4-9.8 percent), and elastic strain energy absorption to bearing failure (8.5-16.3 percent)of the composite joints. The bearing properties increased at a quasi-linear rate with the z-pin content, but were not dependent on pin diameter. Stiffness is improved by z-pins increasing the through-thickness tensile modulus around the bolt-hole of the joint. Post-mortem microstructural examination of the failed joint specimens revealed that z-pins improve the bearing strength by reducing cracking near the bolt-hole via an interlaminar bridging toughening mechanism that involves debonding and frictional sliding of pins within the damaged region. The elastic strain energy to failure is increased by the through-thickness stiffening and toughening provided by the z-pins. This study proves that the reinforcement of bolt-holes with z-pins increases the bearing properties without the weight penalty incurred with the traditional strengthening method of thickening the laminate around holes
UR  - https://drive.google.com/file/d/1gVRQlhooavqIssDP4l5m6ui9ebDrnVXi/view?usp=drivesdk
ER  -