Robin E. Ker



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Two general categories were used to assess the strength of duct tape constructions: adhesive strength and tensile strength. Previously made duct tape backpacks frequently suffered from adhesive failure around the narrowest portion of the shoulder straps, and where small cosmetic patches were applied. When a backpack is lifted, it experiences a force which is greater than the resting weight.The hypothesis states that there is an area of application between two pieces of duct tape such that they will behave as a uniform piece and experience tensile failure, that two sufficiently overlapped pieces can hold within 5% of the load carried by a single piece, and that there is a relationship between the resting weight of a loaded backpack and the load applied to the straps when lifted.Five types of tape underwent tensile and lap shear testing in an Instron 4486 load frame. The tension test specimens were of uniform length, the lap-shear specimens had lengths which varied with the areas of overlap. There were two types of lap shear specimens: with adhesive layers in contact (LSA), and with the adhesive layer of one half adhered to the backing layer of the other (LSN). Maximum load and extension data was collected.Three backpacks were tested to determine the apparent load carried by the shoulder straps and handles when various static loads were applied. The backpacks were lifted with a Desik analog push-pull gauge which recorded maximum load.The maximum loads for the lap shear specimens were within 5% of the tension test results for four types in LSA and three types in LSN. The results for static vs. apparent loading means that a 25 lb. backpack needs to withstand 40 lbs. when lifted. The type of duct tape which is recommended for future backpack construction is 3M 3900.

Publication Date


Project Designation

Honors Thesis

Primary Advisor

Margaret F. Pinnell

Primary Advisor's Department

Mechanical and Aerospace Engineering


Stander Symposium project


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School-Books on Tape: The Tensile and Adhesive Strength of Duct Tape in a College Backpack