Engineered Properties and Structures
FS-FPL-4714

Problem 2:
Properties of structural composite products

The goal of this Problem is to extend the nation's forest resources by developing analytical models and gathering data for predicting the end-use performance of composite structural products.

I. Background

Composite products provide unique opportunities for utilizing the changing forest resource.�However, to effectively use composites for structural products within existing building code systems, we need to understand performance characteristics of these composites.�Of particular interest is the increasing use of hardwood species for the production of structural composites. Relative to what is known about the mechanical properties of softwood species, little is known about the properties of hardwood species. Controversy surrounds the existence and effect of juvenile wood in hardwoods and its effect on mechanical properties.�Even less is known about the effects of genetic selection or management practices on the quality of most hardwoods currently used in structural composites.�Our knowledge of the effect of moisture content and temperature on hardwood properties is at the developmental stage.

II. Body

A. Improve Efficiency

Competition for wood fiber, and the concomitant introduction of small-diameter or underutilized species, offers great opportunities for effective utilization of structural composite materials. Unlike current technology, tomorrow's composites will likely be produced by species not currently used commercially. Likewise, a composite product of the future will likely incorporate a variety of species, unlike the single-species composites produced commercially today.� To effectively use tomorrow's composites it will be necessary to develop analytical/statistical models to predict physical and mechanical properties.�Without such models, we will be lost in a maze of experimental complexity.

B. New Research

This is a new focus area for the RWU.�Past research in the RWU has primarily focused on comparing the performance of existing composite structural products to those of solid sawn lumber. Some past RWU research has evaluate the effect of juvenile wood on mechanical properties for a few selected hardwood species, or evaluated the effect of juvenile wood on the properties of laminated veneer lumber produced from softwood species.�Some research on composites will continue in Problems 1, 3, and 4.�However, a more focused effort is needed, especially to develop analytical models of performance. Currently, no staff are available to focus their research exclusively on the properties and modeling of structural composite products.�However, it is anticipated that a scientist will be added to the RWU within the next 5 years to conduct this research. At that time a Problem Analysis will be the first order of business.

III. Conclusion

1. Develop data and procedures for characterizing the properties of hardwood and softwood species required as input to modeling composite performance.
2. Develop analytical models and data for predicting the end-use performance of composite structural products.