Coefficient of wood bendability as a function of selected factors

- The coefficient of bendability was calculated according to the different equations.
- Wood species and degree of densification have significant effect on the coefficient of bendability.
- Material thickness and number of stressing cycles did not show significant effects on the coefficient of bendability.
- The coefficients of bendability based on the basic bending equation are substantially higher than those based on the geometric approach.

Shaping materials by bending is a frequently used technology. The measure of a material bendability can be taken as the smallest achievable curve radius for the bent material. As bendability depends also on material thickness, this property is most frequently expressed as the ratio of the material thickness and the smallest curve radius achieved. Bending is also an important part of many wood processing technologies. The theoretical expression of wood bendability is, however, rather inadequately studied. The present work focuses on various definitions of the wood bendability coefficient as well as the influence of various factors on its value. In the experimental part of the work, coefficients of wood bendability were defined for beech (Fagus silvatica L.) and aspen (Populus tremula L.) We took the following factors into consideration: wood species (WS) (Fagus silvatica L. and Populus tremula L.), material thickness (MT) (4, 6, 10, and 18 mm), degree of densification (DOD) (10% and 20% of the original thickness), and the number of stressing cycles (NC) (0 versus 10,000). The study brings a new quantitative expression of a bendability coefficient.