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2011

Mobile Apparatus to Mechanically Grade Round Timbers Sponsored By: Dr. Thomas Gorman University of Idaho. Team FlexGrade. Hydraulic Ram. Problem:

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2011

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  1. Mobile Apparatus to Mechanically Grade Round Timbers Sponsored By: Dr. Thomas Gorman University of Idaho Team FlexGrade Hydraulic Ram 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. User Interface Allows user to run experiment with minimal input. Required inputs for each test are: -Specimen ID -Preload % -Diameter -Load Limit -Span Load Cell Mechanical Engineers: David McCord, Lucas Reid Chris Wagner, Brad Tensen, Nate Stephens Computer Scientists: Stephen Fischer, Doug Drobary, Ben Adler Hydraulic Pump/Electronics 2011 Ultrasonic Transducer • 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’ • 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. Support I-Beam Support • 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 Supports Center the log for loading, while minimizing contact stresses. I-Beam Selected to be 15x stiffer than the stiffest log that will be measured to reduce error. Hydraulic Pump/Ram Provide load used to deflect the log, can apply up to 2000 lbs Loadcell Measures load applied by hydraulics to log, accurate to ± 1.5lbs Ultrasonic Transducer Measures deflection of log off of the loadhead, accurate to ± .01 in. User Interface Automates hydraulics, while collecting data from loadcell and transducer. It also calculates the final MoE. Solution: Our solution to this problem was to create a test rig that mimics the design of Dr. Gorman’s in-lab tensile tester. 6inch Diameter Lodgepole Pine Used in 5,000 sq-ft. Library Darby, Montana. Special Thanks to: Dr. Jay McCormack, Dr. Thomas Gorman, Chris Bowers, Joe Plummer, Russ Porter, Joe Thompson

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