Abstract
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.
Highlights
In order to make wood suitable for the purposes of mechanical and, in particular, for automotive engineering, it is important to understand how the material reacts under dynamic load or impact
There is only limited data available with respect to impact loading. This is because loads in civil engineering applications are commonly considered to be quasi-static even if they are cyclic, e.g., for earthquakes, or dynamic, e.g., on bridge piers
Zhao et al [40] has studied the flexural behavior of birch wood at varying temperature and moisture conditions under quasi-static loading
Summary
In order to make wood suitable for the purposes of mechanical and, in particular, for automotive engineering, it is important to understand how the material reacts under dynamic load or impact (see Müller [1] and Müller et al [2]). There is only limited data available with respect to impact loading. This is because loads in civil engineering applications are commonly considered to be quasi-static even if they are cyclic, e.g., for earthquakes, or dynamic, e.g., on bridge piers. 1991-2–2012-03 [4], and the ÖNORM EN 1991-3–2013-12 [5], which are regulating impact and cyclic load cases, refer to equivalent quasi-static loads.
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