Temperature-Related Properties of Solid Birch Wood under Quasi-Static and Dynamic Bending

• Published in: Materials Vol. 13; no. 23; p. 5518
• Main Authors: Baumann, Georg, Brandner, Reinhard, Müller, Ulrich, Kumpenza, Cedou, Stadlmann, Alexander, Feist, Florian
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 03.12.2020; MDPI
• Subjects: birch; Bulk density; Civil engineering; Dynamic loads; Dynamic tests; Energy; Energy absorption; High temperature; Impact tests; Load; Load bearing components; loading velocity; Mechanical properties; Moisture content; Regression analysis; Shear strength; Static loads; Static tests; Temperature effects; Tensile strength; Trees; Norway
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13235518

The project WoodC.A.R. investigates the capabilities of wood and engineered wood-products (EWPs) for their application as a load-bearing material in automotive applications. For crash-relevant components, materials have to provide a high impact bending energy over a wide range of climatic conditions. This study investigates the effect of temperature on the bending behavior of solid birch wood beams (800 × 90 × 43 mm3) under quasi-static and dynamic loading. Specimens were exposed to a three-point bending test with lateral confinement, replicating the hypothetical installation environment in a car, at five temperature levels: −30 °C, 0 °C, +30 °C, +60 °C, and +90 °C. A cylindrical impactor (D = 254 mm, m = 91 kg) was propelled against the center of the beam with an initial velocity of 8.89 m/s (dynamic) and at a constant velocity of 10 mm/min (quasi-static), respectively. Specimens were conditioned in a freezer and a climate chamber, respectively. Temperature was monitored prior and during testing. Bulk density and global fiber deviation were determined afterwards. In both, the dynamic and the quasi-static load case maximum force slightly decreased with increasing temperature, but remained almost constant at temperatures exceeding +30 °C. On average, the maximum dynamic peak force level was twice as high as in quasi-static tests. In the quasi-static tests, the energy absorption remained constant at elevated temperatures (+30 °C to +90 °C) but decreased by about 50% at lower temperatures −30 °C and 0 °C. In the dynamic tests, the energy absorption remained almost constant throughout the entire temperature range.