Abstract: Disclosed are testing apparatus and methods for estimating mechanical properties of nonhomogeneous materials, such as lumber and other wood materials and composite materials, particularly elongated slender members. The testing is appropriate for estimation of tensile and bending strength, tensile and bending moduli of elasticity and possibly other mechanical properties. The testing apparatus include a test specimen support which holds the specimen during testing in a manner which minimizes attenuation of the stress wave which is intentionally generated in the specimen to help predict the mechanical properties. The specimen supports also preferably include means for weighing the specimen which is combined with size information gathered through an optical scanning system thereby allowing the density to be obtained automatically.

Abstract: Methods and apparatuses for non-destructively testing and evaluating mechanical properties of composite materials such as particleboard, plywood, graphic fiber-epoxy composites and other bonded composite materials. The composite material structural elements are subjected to an impact, force or other stress wave producing stimulus. The resulting stress wave is sensed at two different points in time. The speed and attenuaton rate of the stress wave are determined. Measurements of the composite material density are combined with the stress wave speed and attenuation rate into an equation also defined by predetermined experimentally derived parameters. The experimentally derived parameters are specific to the test system, materials, and structural elements being tested. Apparatuses disclosed have sensors which are positioned to determine the stress wave intensity at spaced positions from the stress wave inducing device. The sensors can be retractably mounted and arranged in concentric circles.

Abstract: Disclosed is a testing machine for testing specimens such as lumber which may have varying overall lengths. The testing machine includes the frame having an elongated longitudinal member which can be pivotally mounted with respect to stands. Two sets of transverse arms are connected to the longitudinal member at appropriate points. One set of transverse arms is pivotable. The transverse arms extend outwardly from the longitudinal member and have an extendible and contractible force member for increasing and decreasing the distance between the arms along one side of the frame. Jaw sets are pivotally mounted to the transverse arms opposite from the force member for engaging a specimen being tested. The jaw sets are preferably hydraulically closed, using the same hydraulic supply as used to extend the force member, thus automatically proportioning the gripping force of the jaws with relationship to the applied load to the specimen.