2011

Objective:The objective of this project is to design and build a test rig that is inexpensive and portable; which can grade the strength of small round timbers quickly and accurately, requiring minimal user input.

Mobile Apparatus to Mechanically Grade Round TimbersSponsored By: Dr. Thomas Gorman University of Idaho

Current State of Grading:• Visually Graded• Inaccurate• Logs are graded very conservatively• Based on number of knots, knot size, slope

of grain and major defects• Given a grade of 1, 2, 3 or are marked ‘for

agricultural use only’

Future State of Grading:• Mechanically Graded• Non-destructive• Simply Support the log , place a known center

load, measure the deflection. • Solve for Modulus of Elasticity• Found that logs test with a much higher MoE

than given by visual graders

Support

Load Cell

Ultrasonic Transducer

Hydraulic Ram

Hydraulic Pump/Electronics

Mechanical Engineers:David McCord, Lucas Reid

Chris Wagner, Brad Tensen, Nate Stephens

Special Thanks to: Dr. Jay McCormack, Dr. Thomas Gorman, Chris Bowers, Joe Plummer, Russ Porter, Joe Thompson

Support

Problem:There is a growing demand for small round timber (3-9in diameter) to be used in construction applications. Using visual grading techniques, timbers are currently rated at approximately half of their mechanically determined design strengths.

Solution:Our solution to this problem was to create a test rig that mimics the design of Dr. Gorman’s in-lab tensile tester.

6 inch Diameter Lodgepole PineUsed in 5,000 sq-ft. Library

Darby, Montana.

I-Beam

Computer Scientists:Stephen Fischer, Doug Drobary, Ben Adler

SupportsCenter the log for loading, while minimizing contact stresses.I-BeamSelected to be 15x stiffer than the stiffest log that will be measured to reduce error.Hydraulic Pump/RamProvide load used to deflect the log, can apply up to 2000 lbsLoadcellMeasures load applied by hydraulics to log, accurate to ± 1.5lbsUltrasonic TransducerMeasures deflection of log off of the loadhead, accurate to ± .01 in.User InterfaceAutomates hydraulics, while collecting data from loadcell and transducer. It also calculates the final MoE.

Team FlexGrade

User InterfaceAllows user to run experiment with minimal input. Required inputs for each test are:-Specimen ID -Preload %-Diameter -Load Limit-Span