The tension test parallel-to-fiber in anisotropic materials, such as bamboo, is one of the most important tests because it makes it possible to evaluate mechanical properties used in calculations for different types of stresses. For this type of test there are standards that apply to wood in general, others to bamboo, and other more specific ones that apply to bamboo Guadua angustifolia Kunth. These rules suggest the use of dog bone test specimens. When performing such tests parallel to the fiber direction, failures are observed in undesired zones. This document characterizes and analyzes the possible types of failures. It also evidences the difficulties presented and quantifies them finding that, for 59 failed test pieces, only 18.6% had failures within the desired zones, while the other 81.4% had failures within undesired zones in the tension test parallel to the fiber. Finally, it can be concluded that there are gaps in the rules that influence the variation of the results obtained by different authors. The dog bone test specimens are not recommended for tension tests parallel to the Guadua fiber. Rather, utilization of straight specimens is recommended with a calculated clamping height and the standard equation and protected clamping area.
Lignocellulosic materials that are thermally treated via hydrolysis react chemically, modifying their internal structure, which in turn modifies their physical and mechanical properties, as well as their dimensional stability. Bamboo (Guadua angustifolia Kunth) samples 3 years old, without nodes and without skin, obtained from their basal area were subjected to thermal treatment with temperatures between 160 and 200 °C and duration times between 1 h and 4 h. The severity of the thermal treatment affects the modulus of rupture and modulus of elasticity in compression. The modulus of rupture increased at temperatures up to 180 °C with treatment times of 2 h, i.e., the severity, defined as the product of the temperature and the time varied between 320 (°C*h) and 360 (°C*h). An inflection point was obtained at a temperature of 180 °C after 2 h with a maximum value of 115.1 MPa. The modulus of elasticity increased as the temperature and time increased. The modulus of rupture and the modulus of elasticity of the treated samples increased up to 14.7% and 36.1%, respectively, compared to the not thermal treated samples. Additionally, when the density increased, the resistance and the compression stiffness also increased.
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