The construction industry has relied heavily on wood and wood-based composites, such as oriented strand board (OSB) and plywood for timber frame construction. Therefore, it is highly imperative to categorize the response of wood-based composites when exposed to elevated temperatures for a sustained period of time. The essence of fire-resistant...
A material point method simulation of orthogonal cutting that can simulate cutting into steady-state chip curling is described. The modeling used ductile fracture mechanics using cohesive zone in the cutting path. Robust simulations required a new mechanism to damp kinetic energy artifacts associated with dynamic crack propagation. The simulations displayed...
To better understand the suitability of balsa wood as a core material for sandwich
composites, this paper presents a detailed study of the fracture properties of balsa. The
experiments looked at mode I, mode II, and mixed-mode fracture with crack growth both parallel
and perpendicular to the wood grain direction....
Wood and wood-based composites are being used extensively in single-family residential dwellings. Therefore, it is important to categorize their response when exposed to elevated temperatures for a sustained period of time. In fire-resistant design for wood structures, the main goal is to ensure that enough structural integrity is maintained, during...
We have developed a new approach to the theory of linear dichroism in partially ordered systems. The description of the partially ordered ensemble uses a density of states function, D(θ, ϕ, Δ), which gives the probability that the direction of polarization for incident polarized light has spherical angles θ and...
We have developed a method for the determination of the orientational distribution function of partially ordered systems from the EPR line shape that is an alternative to the usual one of expansion in the elements of the Wigner rotation matrices. The method can be applied to distribution functions whose expansion...
We have developed a method for determining the response of a static, partially ordered ensemble of molecules to various types of electromagnetic probes. In our formalism a physical model is constructued for the orientational distribution function, which is represented as a volume integral over a set of weighting functions. Procedures...
We have expanded on the results of an earlier paper [J. Chem. Phys. 72, 221 (1980)] which deals with a method for determining the response of a static, partially ordered ensemble of molecules to various types of electromagnetic probes. In this paper we consider types of spectroscopy whose response depends...
A single‐photon timing system is described which is capable of extracting fluorescence lifetimes as short as 25 ps. The system is an improved version of an earlier apparatus. The new system uses a synchronously pumped, mode‐locked dye laser with 10‐ps pulses operating at 82‐MHz repetition rate. A fast photodetector and...
We perform two-dimensional linear elastic finite element analysis to investigate the mechanical stability of ultrathin Ge/Si film grown on or bonded to SiO₂, using imperfect interface elements between Si and SiO₂ to model Si/SiO₂ interfacial slippage. We demonstrate that the overall composite film is stable when only the tangential slippage...
Finite element analysis was used to study the effective transverse modulus of solid wood for all possible end-grain patterns. The calculations accounted for cylindrical anisotropy of wood within rectangular specimens and explicitly modeled wood as a composite of earlywood and latewood. The effective modulus was significantly reduced by growth ring...
Fracture toughness of wood and wood composites has traditionally been characterized by a stress intensity factor, an initiation strain energy release rate (G[subscript init]) or a total energy to fracture (G[subscript f]). These parameters provide incomplete fracture characterization for these materials because the toughness changes as the crack propagates. Thus...
A new approach was developed for the evaluation of energy release rate by the virtual crack closure technique in quadratic and linear elements. The generalized method allows arbitrary placement of the side nodes for quadratic elements and thus includes both standard elements, with mid-side nodes, and singularity elements, with quarter-point...