5 research outputs found
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Fluorescence Spectrometry to Quantify Percent Wood Failure in Adhesive Bonds
Structural engineered wood manufacturers need a quantitative measurement technique to determine the ratio of wood to adhesive failure in their shear specimens. Visual estimation of percent wood failure has long stood as an extremely subjective quality control approach according to ASTM D5266 – Standard Practice for Estimating the Percentage of Wood Failure in Adhesive Bonded Joints. The inherent variability between readers often leads to completely different estimates for the same specimen. A UV-VIS spectrometer, coupled with a consistent light source and probe, offers an economic mode of chemometrics for automating the current standard and minimizing said subjectivity. Robust, repeatable, and open-source predictive models will provide a technician with a timely and accurate percent wood failure value after simply placing a lap or block shear specimen under the light probe. This approach is expected to maintain accuracy within five percent wood failure (ASTM D5266) and be as fast or faster than a trained technician.
Three sets of phenol-formaldehyde bonded lap-shear specimens were provided with original ASTM visual percent wood failure estimates by trained technicians from outside organizations. High resolution images of each shear surface were then taken, and these images were evaluated with a grid overlay for an additional, more precise set of percent wood failure estimates. Thereafter, each shear surface was scanned with a probe connected to two separate light sources and data was acquired by a spectrometer. The data, having wavelengths (nm) as explanatory variables and intensity (counts) as dependent variables, was then modelled via RStudio with Partial Least Squares Regression and Simple Linear Regression using the two different wood failure estimates for each population as predictor variables. The results suggest that the grid estimates form better predictive models, and that spectrometry overall is a viable method for quantifying percent wood failure values in shear specimens – with some explained contingencies.Keywords: wood bonding, shear testing, UV-VIS fluorescence spectrometry, Multivariate Data Analysis, Engineered Wood Products, adhesive penetration, surface chemistry, automation, wood failure, machine learning, spectr
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Supporting Grid Image Analyses
Included are three PDF files containing enhanced percent wood failure estimates via Grid overlay for each of the three specimen populations
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Supporting Statistical Models for Fluorescence Spectrometry to Quantify Percent Wood Failure in Adhesive Bonds
Includes Partial Least Squares Regression and Univariate Linear model RStudio code and results in PDF form for each of the three specimen populations scanned by two different light sources. Also included is a generalized PDF document and RMarkdown document for predicting percent wood failure