Author

Onder Tor

Advisor

Zhang, Jilei

Committee Member

Shmulsky, Rubin

Committee Member

Jones, Paul David

Committee Member

Wan, Hui

Committee Member

Martin, William V.

Date of Degree

1-1-2015

Document Type

Dissertation - Open Access

Major

Sustainable Bioproducts

Degree Name

Doctor of Philosophy

College

College of Forest Resources

Department

Department of Sustainable Bioproducts

Abstract

This study investigated effects of pilot-hole diameter, screw penetration depth depth, embedded screw orientation, magnitude of pushing-down force and turning speed on screw driving torques in particleboard (PB) and predicted screw driving torques for two PB clamped together. In addition, effects of material mechanical properties such as shear and tensile strength on screw direct withdrawal loads in PB were investigated and a model to predict screw direct withdrawal load capacity was developed. Furthermore, effects of screw driving torques on clamping pressure between two particleboards were investigated. It was concluded in general that stripping torques (STT) per thread for driving screws into tested PB materials had significantly higher means than seating torque (SET) per thread. The SET and STT per thread for screws driven into PB materials with 0.75-inch penetration depth was higher than 0.50-inch depth when no pilot-hole or pilot-holes with diameter of 1/8 in were drilled. Statistical analyses on screw driving torques for two PB materials clamped together, illustrated that the SET and STT tended to increase when the pilot-hole diameter decreased from 11/64 to 1/16 in. The prediction of the SET and STT values of driving screws through a face into an edge of PB materials can be predicted by the connection of two separate PB materials between a single face specimen with countersink in the surface and a single edge specimen. In addition, a face into a face PB connection, the prediction of both SET and STT can be predicted by connection of two separate face specimens. Results on shear and internal bond (IB) strength demonstrated that there was a clear trend that the shear and IB strengths were higher in the surface of the particleboards than the other levels. In the case of screw direct withdrawal (SDW), the results illustrated that the SDW values of particleboard types did not differ from each other when the pilot-hole diameters of 1/8 and 9/64 in used to drive the screw into the material.

URI

https://hdl.handle.net/11668/20090

Comments

screw driving||particleboard||seating and stripping torques||screw withdrawal

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