This project aims to chronicle the process of building from the architects point of view. Not mindless, mechanical tasks aimed at some economic goal; but tangible, thoughtful work towards an educational and philosophical desire. The desire to be a Master-Builder has fueled architects for centuries. It is a role that the common definition of Architect has all but forgotten. While in practice very few of us will continue this tradition, it is important that we not lose this fundamental aspect of building. To begin to fulfill oneself with this title, the path is very simple: build a building. That is what follows in this book. It is a chronological outline of the design and build of the New River Valley Train Observation Tower. An additional layer to this project is the inclusion of a variety of innovative building materials/techniques, particularity the use of hardwood cross-laminated timber (CLT). This building will serve as an ongoing research opportunity to evaluate the conditions of building with this material in an extreme condition, complete exposure to weather. No work of architecture is a solo endeavor, yet my heavy involvement in the design, documentation, and building of the tower has culminated in a body of work that is distinctly my own. My role was that of a project manager, and I reported to faculty Kay Edge, Edward Becker, and Robert Riggs. This structure allowed me to have a great deal of independence, while vetting my drawings and ideas with experienced professionals. A small group of students joined me in the larger aspects of the build, which provided another opportunity to discover an aspect so critical to building: collaboration. This build taught so much about project management, design, and realization that could only be understood through such a physical experience. / Master of Architecture / This project aims to chronicle the process of building from the architects point of view. Not mindless, mechanical tasks aimed at some economic goal; but tangible, thoughtful work towards an educational and philosophical desire. The desire to be a Master-Builder has fueled architects for centuries. It is a role that the common definition of Architect has all but forgotten. While in practice very few of us will continue this tradition, it is important that we not lose this fundamental aspect of building. To begin to fulfill oneself with this title, the path is very simple: build a building. That is what follows in this book. It is a chronological outline of the design and build of the New River Valley Train Observation Tower. An additional layer to this project is the inclusion of a variety of innovative building materials/techniques, particularity the use of hardwood cross-laminated timber (CLT). This building will serve as an ongoing research opportunity to evaluate the conditions of building with this material in an extreme condition, complete exposure to weather. No work of architecture is a solo endeavor, yet my heavy involvement in the design, documentation, and building of the tower has culminated in a body of work that is distinctly my own. My role was that of a project manager, and I reported to faculty Kay Edge, Edward Becker, and Robert Riggs. This structure allowed me to have a great deal of independence, while vetting my drawings and ideas with experienced professionals. A small group of students joined me in the larger aspects of the build, which provided another opportunity to discover an aspect so critical to building: collaboration. This build taught so much about project management, design, and realization that could only be understood through such a physical experience.

Metal plates are being replaced by lighter but equally strong laminated composite plates in order to improve efficiency and increase performance of aerospace vehicles. But because of the complex construction of laminated plates they are very difficult to analyze. Conventional thin plate theories prove to be inadequate in predicting laminated composite plate behavior. Therefore, a finite element model which incorporates a first- order shear-deformation theory and nonlinear von Karman strains is described. The model is shown to accurately predict deflections in laminated composite plates due to nonuniform transient heat fluxes and transverse mechanical loads. / Master of Science

The present work deals with modes and mechanisms of failure in compression of angleply laminates. Experimental results were obtained from 42 angle-ply IM7/8551-7a specimens with a lay-up of [ (±9) / (=F9)] 6s where 9, the off-axis angle, ranged from 0° to 90°. The results showed four failure modes, these modes being a function of off-axis angle. Failure modes include fiber compression, inplane transverse tension, inplane shear, and inplane transverse compression. Excessive interlaminar shear strain was also considered as an important mode of failure. At low off-axis angles, experimentally observed values were considerably lower than published strengths. It was determined that laminate imperfections in the form of layer waviness could be a major factor in reducing compression strength. Previously developed linear buckling and geometrically nonlinear theories were used, with modifications and enhancements, to examine the influence of layer waviness on compression response. The wavy layer is described by a wave amplitude and a wave length. Linear elastic stress-strain response is assumed. The geometrically nonlinear theory, in conjunction with the maximum stress failure criterion, was used to predict compression failure loads and failure modes for the angle-ply laminates. A range of wave lengths and amplitudes were used. It was found that for 0° S 9 S 15° failure was most likely due to fiber compression. For 15° < 9 oS 35° failure was most likely due to inplane transverse tension. For 35° < e ~ 70° failure was most likely due to inplane shear. For e > 70° failure was most likely due to inplane transverse compression. The fiber compression and transverse tension failure modes depended more heavily on wave length than on wave amplitude. Thus using a single parameter, such as a ratio of wave amplitude to wave length, to describe waviness in a laminate would be inaccurate. Throughout, results for AS4/3502, studied previously, are included for comparison. At low off-axis angles, the AS4/3502 material system was found to be less sensitive to layer waviness than IM7 /8551-7 a. Analytical predictions were also obtained for laminates with waviness in only some of the layers. For this type of waviness, laminate compressive strength could also be considered a function of which layers in the laminate were wavy, and where those wavy layers were. Overall, the geometrically nonlinear model correlates well with experimental results. / Master of Science

Interlaminar stresses are estimated from plate theories by equilibrium. The elasticity equations of equilibrium are integrated with respect to the thickness coordinate z using the linear distribution in z of the in-plane stresses. This procedure, for example, requires fourth order derivatives of the out-of-plane displacement w with respect to the in-plane coordinates x and y to compute the interlaminar normal stress. Since compatible elements for the plate bending problem at most require the displacement and its first derivatives to be continuous across element boundaries, low degree interpolation polynomials are used. Thus, fourth order derivatives of the finite element polynomials are either meaningless, or at least inaccurate. In order to compute high order derivatives, an approximate polynomial solution of high degree to the governing partial differential equation for w(x,y) is determined using the finite element solution as a first approximation. A rectangular subdomain that may consist of several elements is selected from the finite element model. The displacement w(,y) over the subdomain is expanded in a Chebyshev series. Then collocation is used to determine the unknown Chebyshev coefficients such that the Chebyshev series matches displacement w and its normal derivative from the finite element solution at discrete points on the boundary of the subdomain, and the partial differential equation is enforced at discrete points within the subdomain. Interlaminar shear and normal stresses are computed from the third and fourth derivatives, respectively, of the Chebyshev series at the collocation points. / Master of Science

An investigation was conducted to study the constraint effects on flaw growth in composite laminates. Results were presented for the case of a transverse flaw in an interior ply perpendicular to the loading axis. Two orientations of the flawed ply were examined (0 and 90 degrees), and two distinctly different constraint situations were studied (cross-ply constraint and biaxial constraint). Throughout the study, various nondestructive testing methods were employed to evaluate the material response and to determine the damage and damage growth in the specimens. These techniques include replication, ultrasonic c-scan, ultrasonic attenuation, acoustic emission, x-radiography, thermography and stiffness measurement. The effects of constraint on the response of composite materials can be classified in two categories: (a) in-plane effects and (b) through-the-thickness effects. In-plane constraint is the principal contributor to notched strength and changes in notched strength under quasi-static loading. Through-the-thickness constraint controls the pattern and spacing of transverse cracks in the off-axis plies to form a characteristic damage state in the laminates. Out-of-plane stresses produced by constraints are influential on the growth of damage along ply interfaces, especially during cyclic loading. The mode of damage and the extent of damage in constrained notched plies are governed by the stress state in those plies, as determined by the constraining plies, and the relationship of the stress state to the strength state. Maximum constraint on the flawed ply does not produce minimum damage in the laminate; and the lesser degree of damage (in terms of axial splitting and delamination) does not necessarily result in a higher laminate strength or long fatigue lives. In the design of composite structures, a compromise has to be reached with regard to optimizing material parameters such as strength, stiffness, fatigue life, and residual strength. In maximizing one parameter, one might have to sacrifice other requirements on the other material properties in the design. / Ph. D.

A quasi-three dimensional, nonlinear elastic finite element stress analysis of finite width composite laminates including curing stresses is presented. Cross-ply, angle-ply, and some quasi-isotropic graphite/epoxy, laminates are studied. Curing stresses are calculated using temperature dependent elastic properties that are input as percent retention curves, and stresses due to mechanical loading in the form of an axial strain are calculated using tangent modulus, obtained by Ramberg Osgood parameters. It is shown that curing stresses are significant only as edge effects in angle-ply laminates, and severe throughout the laminate in cross-ply laminates. The tensor polynomial failure, criterion is used to predict the initiation of failure, and the failure mode is predicted by examining individual contributions of the stresses to the polynomial. / Master of Science

Torsion of cylindrical shafts has long been a basic subject in the classical theory of elasticity. In 1998 Swanson proposed a theoretical solution for the torsion problem of laminated composites. He adopted the traditional formulation of the torsion problem based on Saint Venant's torsion theory. The eigenfunction expansion method was employed to solve the formulated problem. The analytical method is proposed in this study enabling one to solve the torsion problem of laminated composite beams. Instead of following the classical Saint Venant theory formulation, the notion of effective elastic constant is utilized. This approach uses the concept of elastic constants, and in this context the three-dimensional non-homogeneous orthotropic laminate is replaced by an equivalent homogeneous orthotropic material. By adopting the assumptions of constant stress and constant strain, the effective shear moduli of the composite laminates are then derived. Upon obtaining the shear moduli of the equivalent homogeneous material, the effective torsional rigidity of the laminated composite rods can be determined by employing the theory developed by Lekhnitskii in 1963. Finally, the predicted results based on the present analytical approach are compared with those by the finite element, the finite difference method and Swanson's results. / Master of Science

Changes in the stiffness and strength of notched quasi-isotropic graphite-epoxy laminates were recorded and related to the fatigue damage. Two different laminates [0,90,+45,-45]s (type A) and [ +45, 90, -45, 0] s (type B) were considered and the effects of stacking sequence were compared. Nondestructive testing techniques such as X-radiography, moire technique, acoustic emission, deply technique, and stiffness change were performed to observe damage development. Static properties and damage initiation were related to an approximate stress analysis. Results show that the mechanical response and the fatigue damage depend strongly on the stacking sequence of laminates. In general, residual strength increased remarkably for both laminates due to stress redistributions while the continuous stiffness change curve is typical for each laminate and reflects damage characteristics. Buckling effects as well as matrix cracking and delaminations contribute to stiffness changes. / M.S.

The effect of cooling rate and stacking sequence on fatigue behavior was analyzed for notched quasi-isotropic APC-2 laminates. The fatigue behavior of fast (475° F/min) and slow (1° F/min) cooled specimens of the following two layups was studied: Layup A of (-45/0/45/90), and Layup B of (45/90/-45/0),. All specimens were subjected to a load controlled, Tension - Tension fatigue loading with a stress ratio R = 0.1 at a frequency of 5 Hz. Parameters such as strain, temperature rise across the notch and number of cycles fatigued were continuously monitored during the fatigue tests. Damage was monitored by the reduction in modulus, penetrant enhanced X-ray radiography, and Scanning Acoustic Microscopy (SAM). Post failure analysis of the specimens was carried out by Scanning Electron Microscopy (SEM). A quasi-3D Finite Element Analysis was performed to compare the differences in the interlaminar stresses arising around the notch in the specimens of the two layups under study. The ultimate static strengths did not show any appreciable dependence on either cooling rate or stacking sequence. The maximum load in the fatigue cycle was selected as a fraction of the ultimate notched static tensile strength in each case. The fatigue lives showed appreciable difference between the two cooling rates in layup A when tested at the lower load levels. The fatigue behavior was vastly different between the two cooling rates for specimens of layup B. Also, specimens of layup B, both fast and slow cooled, had longer lives than their counterparts from layup A. A model, based on a constant strain-to-failure criterion, was developed for life prediction and the predicted lives are in good agreement with the experimental values. Fast cooled specimens of layup A showed a gradual degradation in the modulus till failure while slow cooled specimens of the same layup showed a more drastic reduction as they approached failure. No such distinguished behavior was observed in the specimens of layup B. Scanning Electron Micrographs of the fast cooled specimens indicate better fiber/matrix bonding conditions and more matrix plasticity as compared to the slow cooled specimens. A rotated stacking sequence technique was used for the calculation of the interlaminar stresses around the notch. No single stress seems to control failure but it is likely that failure occurs by the interaction of the different stresses since a three-dimensional stress state exists at the notch. Based on this reasoning, effective stresses were calculated at all those interfaces where one of the interlaminar (normal or shear) stresses has a maximum value. A comparison of the effective stresses calculated showed the layup A to be 1.7 times more prone to delamination than layup B. Damage analysis of the fatigued specimens by X-ray radiography and Scanning Acoustic Microscopy shows the specimens of layup A to be dominated by delaminations as compared to those of layup B. The interfaces predicted to be critical by FEA agreed well with the experimental observations, in general. / Master of Science

Based on the principle of virtual displacements, the incremental equations of motion of a continuous medium are formulated by using the total Lagrangian description. After linearization of the incremental equations of motion, the displacement finite element model is obtained, which is solved iteratively. From this displacement finite element model, four different elements, i.e. degenerated shell element, degenerated curved beam element, 3-D continuum element and solid-shell transition element, are developed for the geometric nonlinear analysis of general shell-type structures, anisotropic as well as isotropic. Compatibility and completeness requirements are stressed in modelling the general shell-type structures in order to assure the convergence of the finite-element analysis. For the transient analysis Newmark scheme is adopted for time discretization. An iterative solution procedure, either Newton-Raphson method or modified Riks/Wempner method, is employed to trace the nonlinear equilibrium path. The latter is also used to perform post-buckling analysis. A variety of numerical examples are presented to demonstrate the validity and efficiency of various elements separately and in combination. The effects of boundary conditions, lamination scheme, transverse shear deformations and geometric nonlinearity on static and transient responses are also investigated. Many of the numerical results of general shell-type structures presented here could serve as references for future investigations. / Ph. D.