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ISO 3133 ASTM D143 ISO 3349 EN 310 wood flex

ISO 3133, ISO 3349, and ASTM D143 are all testing standards that determine the flexural material properties of wood beams. A flex test subjects wood to compressive, tensile and shear loading, which replicates the most realistic end uses of the material. ISO 3133, ISO 3349 and EN 310 are specific to static bending, but ASTM D143 includes various other wood test types such as compression, impact, tension, hardness, nail removal testing, and others. The above listed standards are the most commonly used wood flex tests, but many other wood testing standards exist in various organizational bodies including ASTM, ISO, EN, BS, JAS, and JIS.

Wood is widely used as an engineering material in the construction and furniture industries. Before using a wooden beam as a building material, contractors and manufacturers need to know that the beam will hold up appropriately when subjected to the forces and environmental conditions of its end use. Bend testing is an accepted way to compare different types of wood, which is often required when choosing the appropriate material.

Materials Testing System

A typical test set up uses either Instron's 3400 or 6800 series electromechanical dual column universal testing machine configured with a 2820 series base beam and three-point anvil set. The 2820 series wood flex fixture is available in 10 kN and 50 kN capacities. In addition, a yoke deflectometer and clip-on extensometer are available for measuring bending deflections, as specified by ASTM D143.




ISO 3133 / ASTM D143 Test Setup
1) 3360 Universal Testing System
2) Load Cell
3) 2820 Series Bend Fixtures

 

ISO 3133 wood flex test
Tips and Tricks
  • The different standards may have slightly different requirements, which can make complying with 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 center 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. The modular design of the 2820 series of fixtures provides maximum flexibility by offering a range of optional anvils and four-point conversion kits, each complying with different standards.
  • Recording the required amount of data points to accurately detect drops in load due to crack formation and propagation within the material. Bluehill Universal software allows the user to adjust the data sampling rate of the software up to 5 kHz in order to capture a sufficient number of data points.