The ultimate properties of a fibrous composite system depend highly on the transverse mechanical properties of the fibers. Here, we report the size dependency of transverse elastic modulus in cellulose nanocrystals (CNCs). In addition, the mechanical properties of CNCs prepared from wood and cotton resources were investigated. Nanoindentation in an...
Summarizes information on wood as an engineering material.
Presents properties of wood and wood-based products
of particular concern to the architect and engineer. Includes
discussion of designing with wood and wood-based products
along with some pertinent uses.
This work is a compilation of problems that deal with multiscale analysis of transport phenomena in environmental systems. A common feature among the problems studied here is the presence of non-negligible microscale structure in various forms. Each problem is approached from the perspective that a macroscopic observable encodes aspects of...
With recent advancements in material science, industrial operations are being conducted at higher and higher temperatures. This is apparent in the nuclear industry where a division of the field is working to develop the High Temperature Gas Reactor and the Very High Temperature Gas Reactor concurrently. Both of these facilities...
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Brian G. Woods
With recent advancements in materialscience, industrial operations are being
This work focuses on solute mass transport in a highly heterogeneous two-region porous medium consisting of spherical low-hydraulic conductivity inclusions, embedded in a high-hydraulic conductivity matrix. The transport processes occuring in the system are described by three distinct time scales. The first time scale reflects the characteristic time for convective...
Heterogeneous porous material represents a persistent challenge in the field of engineering. Microscale properties such as the porosity and microchannel torturosity significantly control the macroscale transport characteristics of homogeneous porous medium. Additional complexity is introduced when these small-scale features vary in space. Examples of heterogeneous porous systems include artificial body...
Improving existing and developing completely new products is an important part of maintaining a healthy business. This document outlines key principles of new product development, illustrated through the activities of a small sawmilling company.
The fall cone device may be preferable to the Casagrande cup for the determination of liquid limits because it is based on a firm theoretical background and maintains a high degree of operator independence. This makes the fall cone device a superior tool for measuring consistency limits for research and...
The goal was to determine local mechanical properties inside of oriented strand board (OSB) based on a realistic morphology-based finite element (FE) model and data acquired from a physical test performed on the same material. The spatial information and local grayscale intensity from CT-scans obtained from small OSB sample was...
Wood remains the most popular material for deck construction. For centuries, consumers have chosen wood because of its desirable qualities and aesthetics. In recent years, wood plastic composites (WPC's) have seen rising demand as alternatives to wood decks, despite a large price premium. In addition, the removal of CCA treated...
Uranium adsorption to Hanford sediment was studied for various pH, total inorganic carbon concentrations, and total U(VI) concentrations. Both batch and transport studies were done in an attempt to understand the adsorptive trend of U(VI) on Hanford sediment, and the changes in adsorption as both pH and total inorganic carbon...
The U.S, Forest Service regularly removes tons of dead biomass from federal forestlands to control and prevent devastating wildfires. Every year thinning young trees and brush, as well as removing dead biomass from the forest floor generates large quantities of low-grade woody material for which there is little use. Currently...
The advent of synthetic adhesives has transformed the structural applications of wood. However, a persistent issue in adhesively-bonded wood products has been moisture durability. When designing wood based composites, moisture durability will depend on both the wood phase and the adhesive phase. A key question, therefore, is how does one...
Dimensional stability of wood-based composites with changing moisture content remains an important challenge in the industry for many applications. Wood modification technologies have shown significant improvement in dimensional stability by altering the chemistry of the wood substrate, or by filling the available space in the wood microstructure that otherwise would...
The ability of white and brown rot fungi to colonize wood-plastic composites was investigated by measuring weight loss and anatomical changes. Three composite materials were evaluated. The material containing a 70/30 wood-high density polyethylene (HDPE) mixture was most susceptible to fungal attack, while two different 50/50 wood-HDPE composites experienced little...
The strength-normalized fatigue endurance strength of the bulk metallic glass (BMG) Zr₅₂.₅Cu₁₇.₉Ni₁₄.₆Al₁₀Ti₅ (Vitreloy 105) has been reported to be the highest for any BMG; however, to date, there has been no explanation of why this material is so much better than other Zr-based compositions. In this study, the fatigue-crack growth...
Uses for materials with a large surface area and high porosity have grown sig-nificantly in recent years. Porous materials have found usage in applications such as separation, gas storage, sensing, purification and more, prompting researchers to find and discover numerous new porous materials to suit a specific purpose. Hundreds of...
Menstrual health and hygiene insecurity is a global health issue people across the world face, particularly in developing countries. According to the World Bank, an estimated 500 million lack access to adequate menstrual products, and “to effectively manage their menstruation, women and girls require access to water, sanitation, and hygiene...
Engineering capstone projects are intended as a bridge from school to professional practice in which students work in teams to use learned knowledge and skills to complete real-world engineering projects. However, while the majority of time in many undergraduate programs is devoted to development of technical knowledge and skills, there...
Limbless organisms like snakes can navigate nearly all terrain. In particular, desert-dwelling sidewinder rattlesnakes (C. cerastes) operate effectively on inclined granular media (like sand dunes) that induce failure in field-tested limbless robots through slipping and pitching. Our laboratory experiments reveal that as granular incline angle increases, sidewinder rattlesnakes increase the...
The United States Department of Energy has identified the pebble-bed reactor as a high priority for US research with the end goal of licensing a pebble-bed reactor (PBR) for operation in the United States. Before this can be accomplished significant research must be done regarding the safety of the pebble-bed...
Assessing the impact of fungal decay in wood structures poses a major challenge for building inspectors. Although models have been developed to predict degradation rate of building components in varying climatic conditions, most are hampered by the lack of fundamental data on effects of fungal attack on engineering properties. Developing...
This dissertation explores the physiology and gene expression of the ammonia-oxidizing bacterium Nitrosomonas europaea in surface-associated bacterial communities, or biofilms. Biofilms of N. europaea were cultivated in drip flow reactors for several weeks and gene expression microarrays were used to detect 240 genes differentially expressed between the mature biofilms and...
New species introductions have been associated with the movement of
people for thousands of years. For instance, horses were introduced into North
America by Spanish explorers, while pigs were introduced by the Polynesians
into many Pacific islands long before the establishment of permanent
European settlements. Both of these species introductions...
This work describes the fabrication of a high uranium density fuel for the
Reduced Enrichment of Research and Test Reactors Program. In an effort to decrease
the use of high enriched uranium in research and test reactors around the world, new
fuels with high uranium densities must be developed such...
Port Orford cedar (Chamaecyparis lawsoniana) has a reputation for being resistant to fungal attack, but much of the work to support this premise used older growth material (80-100 yr old). Given the tendency for the heartwood from the second growth of some species to be less durable, we evaluated the...
The effects of incorporation of selected biocides on physical and mechanical properties of aspen strandboard were assessed using five copper-based preservatives or zinc borate at three retention levels. Tebuconazole or 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (DCOI) were added as co-biocides to selective copper-based treatments. Mold box tests showed that only panels treated with DCOI...
The potential for preservative migration from treated wood exposed in or above aquatic environments has become a major concern in some parts of the United States. Best management practices (BMP) were designed to decrease the potential environmental footprint of treated wood, but there are few studies assessing the efficacy of...
Wood I-joists are often left uncovered and exposed to the weather during construction, allowing the oriented strandboard and laminated veneer lumber in these systems to be adversely affected by water absorption. Manufacturers typically specify that these materials be protected from wetting, but this can be difficult in wetter climates. There...
A new laboratory technique to simulate the initiation of wood decay and to assess the effects of incipient decay on material properties is described. Douglas-fir heartwood specimens were exposed to brown-rot (Postia placenta and Gloeophyllum trabeum) fungi for various periods. Bendlng properties were determined by nondestructive and destructive tests, and...
ASTM standard sizes for bending tests (either 50 × 50 mm or 25 × 25 mm in cross-section) are not always suitable for research purposes that characterize smaller sections of wood. Moreover, the ASTM standards specify loading the sample on the longitudinal-tangential surface. If specimens are small enough, then the...
In a Modular High Temperature Gas Reactor (MHGTR), the Pressurized Conduction Cooldown (PCC) event is an accident scenario in which there is a loss of forced convection of the coolant through the system but the pressure boundary remains intact. When the PCC event occurs, natural circulation onsets which results in...
Five U.S. high performance research reactors (HPRRs) are currently part of an international nonproliferation program with the objective of ultimately converting their highly enriched uranium (HEU) fuel to a new high density, low enriched uranium (LEU) fuel while still maintaining their reactor kinetic and thermal hydraulic performance. A uranium-molybdenum (U-Mo)...
In a Modular High Temperature Gas Reactor (MHTGR), the Depressurized Conduction Cooldown (DCC) event can be separated into three distinct stages: 1) depressurization, 2) air ingress and, 3) natural circulation. During normal operations, the HTGR utilizes forced convection to move the helium coolant through the reactor core. Thus, during normal...
This report describes the relationship of incising-induced strength loss in bending as a function of preservative treatment and incising pattern, density, and depth of penetration for various machine stress-rated (MSR) grades of full-size 2 by 4 Douglas-fir, Hem-Fir, and Spruce-Pine-Fir (South) dimension lumber. This study may represent a worst-case "incising...
The United States (US) Department of Energy (DOE) has identified the pebble-bed reactor as a high priority for US research with the end goal of licensing a pebble-bed reactor (PBR) for operation in the United States. Before this can be accomplished significant research must be done regarding the safety of...
Sodium cooled nuclear reactors are being considered for the next generation of nuclear power plants to provide clean electricity to the world. To prove the safety of these reactors, the fuel must be shown to safely handle large neutron fluxes that cause a spike in the thermal output of the...
The High Temperature Test Facility (HTTF) is an electrically heated, scaled model of a Modular High Temperature Gas Reactor (MHTGR). Five experiments were conducted to study Depressurized Conduction Cool-Down phenomena stemming from a Double-Ended Guillotine Break (DEGB). After a DEGB, the reactor pressure vessel would depressurize until the pressures are...
The development of cross-laminated timber (CLT) panel technology has opened up new opportunities for wood in tall buildings. Several characteristics including seismic performance and speed of construction have raised interest among designers. As CLT gains acceptance in the industry, alternative structural solutions need to be investigated to improve performance of...
The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes...