1. Department of Bioengineering Structural Properties of Glued-Wood Surrogates 102B_4 Yang Zhang – Background & Hypothesis Kevin Clark – Methods & Protocol Jason Phan – Deliverables & Pitfalls Amit Khasgiwala – Equipment & Budget

2. Department of Bioengineering Background: Biological glues are currently being used to heal broken cartilages. To function properly, the cartilages glued together must have similar structural properties to a whole cartilage. Aim & Hypotheses : Aim: To compare fracture energies needed to break wood surrogates with and without glues of different adhesive strength Hypotheses: -Wood surrogates repaired with glue consisting of lower or higher adhesive energies, will require a lower or higher energy, respectively, to fracture -The wood will fracture at a different location than the glued location if the adhesive strength of glue is higher than that of the wood Yang Zhang

3. Department of Bioengineering Methods & Protocol: 1.Calibrate and balance the Instron machine. Set the crosshead speed to 5 mm/min and the sampling rate to 15 measurements per second. Also measure the distance between the supports in the Instron machine to make sure it is approximately 7 cm apart. 2.Perform a 3-point bending test on one wood surrogate (cross-sectional area of 9.50mm x 2.10mm). Repeat for 5 wood surrogates. 3.Record the force and displacement data, and tabulate failure load, fracture energy, and stress. 4.Cleanly cut the next set of 5 surrogates to attain same cross-sectional area. Apply the same amount of Titebond HiPURformer Adhesive to each piece and reattach the 5 cut wood samples, clamping them for 5 minutes at approximately 100psi. 5.Repeat steps 2-3 with reattached samples noting the location of fracture. 6.Repeat steps 4-5 with Titebond III Ultimate Wood Glue, clamping for 10 min at approximately 100psi. 7.Using one-tailed T-tests, determine if each type of glued sample had a higher/lower failure load and facture energy than the intact wood. Kevin Clark

4. Department of Bioengineering Proposed Deliverables/Findings: Potential Pitfalls: Wood glue with a lower adhesive strength will require lower fracture energies (higher adhesive strength glue will require a higher fracture energy) If the wood glue has a lower adhesive strength than the wood, then the glued- wood surrogate will fracture at the originally cut location The glue could tear prematurely if not enough drying time is provided, not enough force is used to reattach the cut wood surrogates back together, or the glue is not applied uniformly The cross-sectional area tested may not be large enough to distinguish between different types of glues Jason Phan

5. Department of Bioengineering Equipment: 20x Popsicle Sticks each 114.30mm x 9.50mmx 2.10mm: To be used as wood surrogate Instron Model 4444 bench top materials testing machine: Used to apply force onto surrogates Supplies: calipers, rulers, knife & clamp: To measure dimensions and cross-sectional area of surrogates, and to cut & reattach the cut surrogates Amit Khasgiwala Newly Purchased Equipment:  16.0oz Titebond III Ultimate Wood Glue (see www.titebond.com): Has quick set time (10 min) and offers higher bond strength (4000psi) than surrogates’ failure stress (530psi). $8.99 at www.amazon.com  3.8oz Titebond HiPURformer Adhesive (see www.titebond.com): Has quick set time (10 min) and offers lower bond (270psi) strength than surrogates’ failure stress(530psi). $6.99 at www.amazon.com