5.02.01 - Non-destructive evaluation of wood and wood-based materials
Nondestructive evaluation (NDE) is the science of identifying the physical and mechanical properties of a material without altering its end-use capabilities and then using this information to make decisions regarding appropriate applications. Such evaluations rely upon nondestructive testing technologies to provide accurate information pertaining to the properties, performance, or condition of the material in question.
The Working Party concerns with all aspects of NDE of wood and wood-based materials and various wood products. It also concerns the research needs and development in the field of structural condition assessment of wood buildings and historic structures. The working scope is intended to cover the techniques that are non-intrusive and/or do not impair the processing or functionality of the object studied. As such, NDE includes both nondestructive and quasi-destructive techniques, and often is done in conjunction with destructive tests for data verification. The typical NDE technologies that are being used or developed for wood applications include the following:
The Unit sponsors and supports regional and international events such as technical meetings, trainings, workshops, and symposia. Our goal is to promote effective communication and information dissemination on most resent research advancements and refinements in NDE field and bridge the gap between research and industrial applications.
State of Knowledge
NDT - An Original Challenge to Wood Technology
Excerpts from the keynote address given by Dr. Helmuth Resch at the 14th International Symposium on Nondestructive Testing of Wood
Needs and Opportunities
NDT is needed as an integral part of manufacturing for the optimization of volume and quality of output from each tree. Modern scanning technology is essential to measure sawn, peeled, sliced, or chipped products and optimize sorting and further conversion. The technology must be able to direct each log and subsequently each semi-product to the most appropriate use by scanning with dimensional accuracy for the true log shape and growth characteristics.
Original scanning technology had only been used in sawmills and veneer plants to maximize volumetric yield, to detect the usable area, and eliminate wane in edging of boards. Advanced scanning of growth characteristics is, however, required, if at a reasonable cost, to gain knowledge of the internal quality of logs before conversion in terms of the extent of knots, grain direction, growth rate, and density. Such information aids the direction already of logs towards conversion for the most suitable market. Scanning technology becomes even more important as the industry strives to utilize timber to sell into the highest value markets maintaining a high product quality output throughout. For this, simple defect recognition on sawn boards may not be sufficient. More refined assessments are required including the measurement strength- and appearance-reducing defects which can be minimized by re-engineering for a higher structural grade or removed to facilitate a high value re-engineered product.
Moisture content recognition as part of quality control is vital in all branches of the forest products industry. In general, but especially in construction, the moisture content of timber supplied is often too high leading to a variety of problems. The need to establish precise moisture content limits for specific products is recognized, but specifications are often compromises between producer and customer groups. Improved, more rapid methods for determining moisture contents are desired for a number of production stages, but especially in conjunction with stress rating and rating of lumber and veneer.
Despite significant investment by the sawmill industry to improve grading for strength and appearance of surface defects, as well as kiln drying technologies and scanning equipment, there are still opportunities for enhancements to improve the competitiveness of timber products with other materials and for timber products to maintain or increase its market share.