This report is one of a series issued in cooperation with the Army-Navy-Civil Committee on aircraft design criteria under the supervision of the aeronautical board. Information reviewed and reaffirmed 1962. Original material published 1944.
This thesis investigates a simple dynamic model of the hind leg
of a beetle during initiation of a step. The primary assumption was
that the full load of the body was carried on the hind leg during
this time. That is, the only forces on the body were that of...
This report is one of a series issued in cooperation with the Army-Navy-Civil Committee on aircraft design criteria under the supervision of the aeronautical board. Information reviewed and reaffirmed 1962.
Ti-6Al-2Sn-4Zr-2Mo-0.1Si specimens were shaped by repeated cycles of heating
(to 954 °C) and hammer or press forging followed by a solution anneal that varied from
968 to 998 °C. The coupons were originally extracted from billets forged below the beta
trans us ( 1009 °C) and slow cooled to ambient...
The rheological, color, micro-structural, and electrical properties of surimi seafood gels were investigated. Various starches and protein additives at different ratios were evaluated with Alaska pollock surimi under ohmic heating at different heating rates to determine their functional properties and further to compare these properties with those of conventionally cooked...
This report is one of a series issued in cooperation with the ANC-17 Panel on Plastics for Aircraft of the Departments of the Air Force, Navy, and Commerce. Information reviewed and reaffirmed 1960. Original report issued November 1955.
Identifying material characteristics of composites is important in designing any
structural system. The aerospace industry relies on these material properties not only to
design a functional aircraft, but also a safe and reliable one. Since carbon fiber
composites are relatively new materials, little is known about its characteristics under
certain...
Identifying material parameters in composite plates is a necessary first step in a variety of structural applications. For example, understanding the material parameters of carbon fiber composite is important in investigating sensor and actuator placement on micro-air-vehicle wings for control and wing morphing purposes. Knowing the material parameters can also...
Polymeric composites reinforced with bio-materials have advantages over composites with synthetic reinforcements. Bio-based composites use low-cost and renewable reinforcements, have nonabrasive properties for machining, have improved damping characteristics, and have potential for energy recycling. However, the limited use of bio-based composites is because their mechanical properties are typically much lower...
The overall goal of this project was to design a wood frame shear wall that could withstand greater displacement before damage occurred to the Gypsum Wall Board (GWB). More specifically, the objectives of the study were: (1) to evaluate damage to the GWB in alternative shear wall designs at 1%,...
The tendency of wood to shrink and swell with changing moisture content remains as one of the most significant challenges to using wood in its many applications. Viscoelastic Thermal Compression (VTC) has been shown to significantly increase the density, strength and stiffness of wood. However, dimensional stability is still a...
Total US lumber production in 2011 was 77.9 million cubic meters. Its primary use was for housing and construction. There is a growing concern that the structural properties for wood are being reduced as trees are harvested at much younger ages as the wood supply shifts from older to younger...
The development and some applications of holographic optical tweezers (HOT) are presented. Our HOT system uses a spatial light modulator (SLM) to control the location and properties of the optical trap. We have developed a method for optimizing the diffraction efficiency of a SLM that can be applied in situ...
Wheat (Triticum aestivum) is a globally traded staple food crop. The diverse and pleasing nature of wheat-derived products is a result of the complex interactions of the polymeric components from the wheat endosperm. Changes in the functionality of these polymeric components, as a result of changes in growing conditions or...
Understanding the effect on the materials mechanical properties from the perspective of interfacial interaction between the filler and the polymer matrix has become an important criterion in polymer nanocomposites field. Cellulose nanocrystals (CNCs) are renewable materials that can be extracted from natural sources, such as wood, cotton, and tunicates. In...
Anterior cruciate ligament injuries are common in a wide variety of sports and most frequently occur during activities requiring rapid deceleration such as landing and cutting. Deceleration of the body's center of mass during movement results primarily from eccentric muscle contraction. This type of contraction serves to absorb energy from...
The breaking radii of variously discolored veneers of six different hardwood species were small enough, for most of the discolorations, to indicate that such veneers can be used successfully on members having curved surfaces. When expressed in terms of the minimum radius of curvature attained without fracturing, the breaking radius...
The collapse of the I-35W Bridge in Minneapolis, MN in 2007 prompted an investigation into the design and inspection of the steel truss bridges. Further investigation into the collapse revealed that a gusset plate experienced sway buckling, causing the bridge failure. This bridge failure motivated research into the analysis and...
Most specifications for ready-mix concrete (RMC) limit mixing time to 90 minutes and/or truck drum revolution counts (DRC) to 300 before discharge. These specifications have been in place for many years with the objective of ensuring the quality and performance of the finished concrete product. However, limited research has been...
The structural and stress changes in molybdenum/amorphous silicon (Mo/a-Si)
EUV reflecting multilayers during annealing at 316°C were studied. The amorphous
interlayers, with an Mo:Si stoichiometry of 1:2, grew during annealing. The residual
stresses in each component of the multilayer also changed significantly. Through high
resolution electron microscopy, selected area electron...
A lightweight carbon fiber reinforced polymer (CFRP) c-channel beam was previously designed using analytical theory and finite element analysis and subsequently manufactured through a pultrusion process. Physical testing revealed the prototype did not meet the bending and torsional stiffness of the beam model. An investigation revealed that the manufactured prototype...
Angular correlations of gamma rays from excited states of ¹⁶⁶Er have been
measured following the β decays of ¹⁶⁶ Ho (Jπ =7-, t 1/2 =1200y, Q= 1854 ke V) and ¹⁶⁶Tm (Jπ = 2+, t 1/2, = 7.7h, Q=3040 keV).
Data was collected using the 8π
spectrometer, an array of...
Local material damage that occurs within cellular solids, such as polymer foams and trabecular bone, and precedes local fractures of the cell struts or walls is called micro-damage. The accumulation of micro-damage within cellular solids is often undesirable, although it is thought to be vital to the development and health...
Effects of moisture content, pH, and salt concentration on dynamic rheological properties and gel fracture quality of Pacific whiting surimi were investigated. Torsion tests showed that shear stress decreased rapidly and strain values decreased gradually as moisture concentration increased. As pH increased, fracture shear stress and strain values increased, whereas...
Moisture intrusion in residential structures can lead to substantial fungal decay and this damage costs billions in repair/replacement costs. The extent of damage and the rate at which it occurs are primarily dependent on the wood moisture content and temperature in the structure. Determining the risk of decay for various...
Large numbers of reinforced concrete deck girder bridges that were constructed during the
interstate system expansion of the 1950s have developed diagonal cracking in the stems.
Compared to the present AASHTO-LRFD standards, the provisions of the 1950s allowed
for higher shear stress in the concrete, thus reducing the amount of...
Ever since composite laminate technology was introduced into the aerospace and automotive industry, there has been a need to fully understand the damage progression experienced by composite laminated plates in the presence of a notch. While numerous research studies have been conducted on this matter when subjected to in-plane loads,...
Wood stiffness is one of the most important properties of lumber and veneer. We studied wood stiffness (modulus of elasticity, MOE), wood density, microfibril angle, and knots in a 25 year-old wind pollinated progeny test (50 families, ~ 373 trees) of coastal Douglas-fir to understand the potential for genetically improving...
For resin based dental restorative composites, one of the major challenges is to optimize the balance between mechanical and optical properties. Although fracture is the second leading cause of dental restorative failures, very limited mechanistic understanding exists on a microscopic level. In the present study, the fracture properties and mechanisms...
Steady flow fields and flow-induced wall stresses have been evaluated by experimental measurements and computational fluid dynamics (CFD) analysis in a series of patient-specific abdominal aortic aneurysm (AAA) models, over a range of Reynolds numbers (Re) from 125 to 3000 (500 to 3000 for CFD). Experimental methods used particle image...
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...
Forest products companies in the U.S. face vigorous competition from other wood
producers around the world and other industries (steel, aluminum, plastics,
composites). To be competitive, forest companies need to control costs, sort and
allocate logs to the most appropriate markets, and recover more value at time of
harvest. Interest...
To remain competitive, the forest products industry needs to look for new and innovative processes and technologies to not only reduce costs but also to recover more value through the entire seedling-to-customer forest products supply chain. It is well recognized that measuring wood properties of logs in real time during...
This report is one of a series issued in cooperation with the ANC-23 Panel on Sandwich Construction for Aircraft of the departments of the Air Force, Navy, and Commerce. Information reviewed and reaffirmed 1965. Original report issued March 1957.
This report is one of a series issued in cooperation with the ANC-23 Panel on Composite Construction for Flight Vehicles of the Departments of the Air Force, Navy, and Commerce. Information reviewed and reaffirmed 1962. Original report issued January 1956.
This report is one of a series issued in cooperation with the ANC-23 Panel on Sandwich Construction of the Departments of the Air Force, Navy, and Commerce. Information reviewed and reaffirmed 1960. Original report dated August 1955.
This report is one of a series issued in cooperation with the ANC-23 Panel on Sandwich Construction of the Departments of the Air Force, Navy, and Commerce. Information reviewed and reaffirmed 1962. Original report issued September 1955.