Materials Engineering Department
BS in Materials Engineering
Previous studies have shown that heat treatments have the ability to improve mechanical strength and stiffness in hardwood species. Compared to structural hardwoods, bamboo is a more sustainable and globally viable renewable resource. Therefore, Bambusoides vivax (timber bamboo) culms were fabricated into flat, rectangular cross-section samples with varying cellulose content to be heat treated and tested for mechanical properties. All samples were heat treated (HT) twice. The first HT was a normalization of all samples at 103 +/- 3 °C. The second HT was performed at various times and temperatures ranging from 130°C to 170°C for 0.5 to 3 hours. Post HT, the samples were loaded until failure in a three-point bend apparatus on an Instron 150 kN load frame based on the specifications of ASTM D790-03. The specimens were loaded to fail under tensile stress along the fiber-dense side of the bamboo sample, which was seen to reduce variance in earlier testing. From initial pilot testing, an increase in flexural strength of 70% and an increase in relative flexural stiffness of 30% were seen in samples that had undergone 1 hour HTs at 103 +/- 3 °C and 160 +/- 3 °C compared with samples that had not undergone HT. Formal testing displayed an average flexural strength of 200 MPa and an average flexural stiffness of 50 MPa compared to the non-heat treated samples which displayed a 100 MPa flexural strength and 30 MPa flexural stiffness. No statistically significant difference was determined between the different heat treatments, although all heat treated samples performed to statistically higher degrees than the non-HT samples.
Available for download on Wednesday, June 10, 2020