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Publication Number: FHWAHRT04096
Date: August 2005 
Evaluation of LSDYNA Wood Material Model 143PDF Version (8.16 MB)
PDF files can be viewed with the Acrobat® Reader® 3  Timber Compression Test CorrelationsFPL performed fullscale tests on dry southern yellow pine timbers in compression parallel to the grain.^{(6)} A schematic of the test setup is reproduced in figure 4. The timber cross section is 15.24 centimeters (cm) by 15.24 cm, and the timber length is 304.8 cm. Loaddeflection histories were measured for select structural and grade 2 timbers. Moisture content, failure location, and defectinitiated failures were documented. The average moisture content is 12 percent, although measurements as low as 7 percent and as high as 18 percent were recorded. The average strength measurements are:
The default strength of clear wood at 12percent moisture content is 52.7 MPa. 1 inch = 25.4 millimeters (mm), 1 pound force (lbf) = 0.004448 kilonewton (kN) Figure 4. Schematic of FPL timber compression test setup. The developer performed multielement simulations of these tests to:
Comparisons of the simulations with the test data are shown in figure 5 as a function of grade. The black lines are the simulations. The red and colored lines are the test data. The colored lines highlight specific data curves whose strength is approximately average. Loaddeflection curves from two calculations are shown in each plot. One curve is a clear wood simulation that models a higher yield strength than measured. The second curve applies a strengthreduction quality factor (Q_{C}) to the compressive strength to correlate the calculated yield strength with the measured yield strength. A good correlation of the select structural simulation is obtained with a factor of Q_{C} = 0.49 applied to the compressive strength. This factor is the ratio of the average select structural timber compression strength (25.7 MPa) divided by the average clear wood compression strength (52.7 MPa) at 12percent moisture content. A good correlation of the grade 2 simulation is obtained with a factor of Q_{C} = 0.43 applied to the compressive strength. This factor is the ratio of the average grade 2 timber compression strength (22.7 MPa) divided by the average clear wood compression strength (52.7 MPa) at 12percent moisture content. No quality factors are applied to the stiffness, although a factor of 0.8 is probably reasonable for grade 2. These comparisons were made with different hardening parameter values for each grade. Good correlations could not be achieved using the same hardening parameter values for each grade. Therefore, the default material property methodology was set up to specify hardening parameters as a function of grade. This is more thoroughly discussed in the wood model user’s manual.^{(2)} 
Topics: research, safety, infrastructure, materials, construction safety Keywords: research, safety, infrastructure, materials, wood, southern yellow pine, Douglas fir, LS DYNA, modeling and simulation, damage, rate effects, plasticity TRT Terms: RoadsGuard fencesMathematical modelsEvaluation, Wooden fencesMathematical modelsEvaluation, Wood structures, Posts, Dynamic models, Finite element method, Simulation Updated: 04/12/2012
