Biomechanics

A Pair of Three-Point Bending Testers for Outdoor Use

By Steven Vogel, Duke University


Type of Resource Laboratory activity 
Topic Structures 
Taxa Plant 
Organizational Level Organismal 
Estimated time to do activity 2 to 3 hours 
Background required/level Minimal algebra and physics—could even be used in a high-school physics lab.  
Role of activity in your course (No current course)  
What students might learn from this course or activity Experience extracting real data from living material in nature.
Practical sense of the meaning of flexural stiffness and Young's modulus.
The value of simple, built-to-order, apparatus.  
Special tools, equipment or software needed The devices have to be built. They require nothing that isn't either generally available (e.g. paper clips) or obtainable from lumber/hardware store (wood, cord, hinges and brackets) and fabric shop (elastic thread). A pair of testers should cost less than $25.00, assuming no labor charge.  
Safety precautions, possible permissions necessary None  
Miscellaneous advice - pitfalls to avoid In a way, the best thing is to let students discover the pitfalls, learning that a certain amount of improvisation and dexterity is prerequisite for using simple gear.  
Frequently asked questions by students (As yet uncertain)  
Description Two simple and inexpensive devices for measuring flexural stiffnesses of the trunks and branches of trees—or other structures. They ought to demystify the process as well as providing experience obtaining real data from nature.  
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