Understanding the effects of lamination thickness variations on bond integrity in cross laminated timber
Graduate Student Name
Samson Micheal Idoghor
Email Address
Faculty mentor/Supervisor
Prof. Lech Muszynski
Email Address (Faculty mentor/Supervisor)
Department Affiliation
Wood Science & Engineering
Job Location
Richardson Hall, Emmerson Laboratory, Oregon State University
Description of project or research opportunity
The application of any kind of layered adhesive-bonded wood-based composite for structural use like glulam, cross-laminated timber (CLT), plywood, e.t.c. the bond integrity of such a composite is of importance. The bond integrity can be affected by several factors, such as species of wood, adhesive types and systems, moisture content, glue spread rate, and clamping pressure e.t.c. However, in CLT, clamping pressure may depend on the thickness variation in all layers that even moderate variation in the thickness between the same layer results in a variation of pressure on cross-intersections of the various layers of the lamination. The PRG320 standard requires a 0.20mm threshold for thickness tolerance but did not provide much empirical evidence to support it or how they came about it. Maintaining tight thickness tolerances comes with cost implications in an industrial setting and is particularly difficult to replicate in laboratory settings or pilot-scale production. CLT prototype development in the laboratory or pilot line often faces a higher rate of delamination, and this failure is often blamed on the adhesive and species compatibility, yet thickness variation might be the reason for such failure.
GOALS
The goal of this research project is to determine the contribution of thickness variation in cross-laminated timber (CLT) laminations to the bond formation process, the resulting bond integrity, and the failure patterns in CLT panels.
The specific objectives of this research project are
1. Determine the effect of thickness difference in adjacent laminations on pressure transfer and adhesive bond formation between layers.
2. Measure bond integrity distribution in CLT specimens with known thickness tolerance.
3. Analyze failure mechanisms in laboratory-manufactured CLT specimens with known thickness tolerance.
4. Deploy computer modelling to investigate the effect of thickness variations on load transfer through layers during pressing, and use damage mechanics modelling to predict
METHODS
The method employ the use of empirical tests and coupled with numerical modelling and
1. Determination of the effect of thickness tolerance in adjacent laminations on inter-laminar pressure transfer using digital image correlation (DIC)
2. Determination of pressure transfer in small dry CLT layups
3. Measurement of adhesive strength distribution in 10' x 8' laboratory manufacture CLT panels with known thickness variation. This involve fabrication of CLT panel, dissecting the entire panel and perform delamination and block shear test
4. Analysis of failure mechanisms in the laboratory manufactured CLT panels with known thickness variation. This involve testing the manufacture CLT panel to failure and record the failure modes, and generation of failure map distribution of the panels.
GOALS
The goal of this research project is to determine the contribution of thickness variation in cross-laminated timber (CLT) laminations to the bond formation process, the resulting bond integrity, and the failure patterns in CLT panels.
The specific objectives of this research project are
1. Determine the effect of thickness difference in adjacent laminations on pressure transfer and adhesive bond formation between layers.
2. Measure bond integrity distribution in CLT specimens with known thickness tolerance.
3. Analyze failure mechanisms in laboratory-manufactured CLT specimens with known thickness tolerance.
4. Deploy computer modelling to investigate the effect of thickness variations on load transfer through layers during pressing, and use damage mechanics modelling to predict
METHODS
The method employ the use of empirical tests and coupled with numerical modelling and
1. Determination of the effect of thickness tolerance in adjacent laminations on inter-laminar pressure transfer using digital image correlation (DIC)
2. Determination of pressure transfer in small dry CLT layups
3. Measurement of adhesive strength distribution in 10' x 8' laboratory manufacture CLT panels with known thickness variation. This involve fabrication of CLT panel, dissecting the entire panel and perform delamination and block shear test
4. Analysis of failure mechanisms in the laboratory manufactured CLT panels with known thickness variation. This involve testing the manufacture CLT panel to failure and record the failure modes, and generation of failure map distribution of the panels.
Tasks student will perform
1. Preparation of wood specimens (cutting, measuring lamella thickness)
2. Labeling of specimen and measurements
3. Support pressing operations and sample conditioning
4. Assist in the conduct of delamination, block shear, and mechanical tests
5. Assist with recording and organizing experimental data in Excel
6. Maintain a clean and safe laboratory environment
2. Labeling of specimen and measurements
3. Support pressing operations and sample conditioning
4. Assist in the conduct of delamination, block shear, and mechanical tests
5. Assist with recording and organizing experimental data in Excel
6. Maintain a clean and safe laboratory environment
Special skills required
Strong attention to detail, the ability to follow experimental protocols, basic knowledge of Wood Science or Materials Science, familiarity with workshop tools, hands-on lab skills, accurate data recording, awareness of lab safety procedures, and a willingness to learn and perform repetitive tasks.
Proposed dates of employment
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