Wood is commonly employed as an engineering material in the construction and furniture industry. With its broad range of physical and mechanical properties, wood from different species of trees can be chosen to suit specific application requirements. The strength of wood is influenced by factors, such as the types of loading, direction and duration of loading, moisture content and temperature. Standards, such as ASTM D143, cover testing methods to determine the mechanical properties including flexure strength, tensile strength and shear strength of wood. This allows engineers to compare the properties of various species before choosing one which best fits the engineering requirements.
The different standards may have slightly different requirements and this can make complying to multiple standards a challenge to achieve. For example, ASTM D143, states that the lower support anvils of the three-point static bend fixture should be provided with bearing plates and the load should be applied to the centre of the specimen by a rigid upper block. However, ISO 3133 states that the support and load applying anvils should be rollers of a specified diameter.
To ensure that primary failure of the specimen arises from either tensile or compressive stress, and not shear stress, many wood bend testing standards require a set up with a minimum span-to-depth ratio of 14. A typical test set up would be to use either our 3300 or 5500 series electromechanical testing machine configured with the 2820 series base beam and three-point anvil set for this test. In addition, a yoke deflectometer is available for measuring bending deflections with respect to the neutral axi, as specified by ASTM D143.
The 2820 Series of wood bend fixtures are designed in accordance with common International Standards for performing flexure tests on a range of wood products. The modular design of this series of fixtures provides maximum flexibility by offering a range of optional anvils and four-point conversion kits, each complying with different standards. This allows the fixtures to be configured to meet a wide range of standards while sharing as many common parts as possible.
Our Bluehill® Flexure Software Module provides test control and result calculations required by most flexure tests. This module allows for measurements of six different types of modulus, outer fiber stress and strain, four types of yield, break, pre-set point detection, peak values, and creep/relaxation (total and delta). In addition, it supports both three and four-point flexure tests.