Tech Directions - May 2008 - (Page 17)

Balsa Tower Walls Brave ‘Big Buster’ By George Granlund ggranlund@spsd.net L IKE many technology teachers, I try to stretch my budget by “milking” each student activity for maximum benefit. In our technology department, we use balsa wood towers to teach the basics of structural engineering. To get the most from our materials, we’ve shifted from a four-sided balsa tower destined for failure testing to a single tower side. In this article, I will detail my structural engineering activities and provide a procedure Fig. 1— Practice balsa square teachers can use to build a testing device that I call “Big Buster.” Educators can use the activities on a standalone basis to teach the basics of structural engineering or as an introduction to a more in-depth investigation of how structures perform. Teaching Structural Engineering Our 9th-grade Applied Technology classes examine structural engineering from the standpoint of the George Granlund is a technology education teacher, Arthur Hill High School, Saginaw, MI. forces and stresses placed on a structure when it is under compressive load. Students try to design a lightweight structure that will achieve maximum structural efficiency. Since balsa is a very lowdensity wood, students cannot rely solely on the material for strength as they might, say, with steel. I tell them that the structural integrity of their balsa structure must be engineered into it rather than come from simply using a lot of material. We begin our structural engineering unit with an activity in which students place a load on small beams that have various cross sections and spans. Students then measure and compare the amounts of deflection. They learn that shorter spans and thicker cross sections result in a lower deflection. This gives a clearer understanding of how wood Best reacts when placed under a load. In a second activity, students perform simple compression tests on paper and poster board columns that have a variety of cross sections, shapes, and lengths. They learn that structures with larger cross sections and shorter lengths can remain more stable under compressive loads. Fig. Once students see how loads affect structural members, they construct a small two-dimensional balsa structure (Fig. 1) to learn basic skills in joining small materials and to develop good craftsmanship (Fig. 2). Once students exhibit a degree of proficiency in using a hobby knife and emery board, I give them a plan for the single side of a balsa tower (Fig. 3). While this design provides no room for creativity, it allows students to compare their construction ability with others in the class. As an assembly platform, we use a piece of foam core or cardboard covered with waxed paper. The pattern is slid under the waxed paper and straight pins serve as Poor Poor Good Poor 2—Balsa square craftsmanship www.techdirections.com PRE-ENGINEERING 17 http://www.techdirections.com

Table of Contents Feed for the Digital Edition of Tech Directions - May 2008

Tech Directions - May 2008 Contents Technically Speaking Direct from Washington The News Report Mastering Computers Technology's Past Technology Today Road to Success - Service Learning Enhances Tech Ed Experience Balsa Tower Walls Brave 'Big Buster' These Kids Are Really on the Ball - Inventors Competition Winners School Web Site of the Month Animator Career Exploration Tools Guide Index to Volume 67 More than Fun

Tech Directions - May 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.