Academic literature on the topic 'Beams with straight cable'

Abstract Little information on experimental investigations regarding the influence of the prestressing forces in the shear resistance of prestressed beams is found in the technical literature. Thus, it was experimentally evaluated the shear resistance of six post-tensioned prestressed concrete beams with cross section of (150 x 450) mm2, total length of 2400 mm and concrete's compressive resistance of 30 MPa, with the variables of this work being the layout of the prestressing cable, straight or parabolic, and the stirrups geometric rate. Verticals displacement, steel and concrete's strains and a comparison of the experimental loads with the estimates of ACI 318, EUROCODE 2 and NBR 6118: 2014 codes are presented and discussed. The results showed that the cable's parabolic layout increased the beams' shear resistance in up to 16% when compared to beams with straight cables.

Progressive collapse, the extensive or complete collapse of a structure resulting from the failure of one or a small number of structural components, has become a focus of research efforts and design considerations following events occurring at the Ronan Point apartment building in London, the Murrah Federal Building in Oklahoma City, and the World Trade Center in New York City. A principle research and design area for progressive collapse investigates the behavior of structural frames when column support is removed. The mechanism that results from loss of column support in structural frames characteristically involves beams that are unable to provide sufficient flexural resistance. Cable retrofit is one method to enhance existing frames and supplement or replace the post-mechanism beam load resistance with straight-legged catenary resistance after a column removal. The cables are located linearly along the beam geometry and are affixed at beam supports. This paper investigates both static and dynamic behavior of the catenary action of retrofit cables, which include both the linear and nonlinear material behavior of the cable material. Moreover, a simplified model serves as the basis for retrofit cable design is presented. Finite element modeling and experimentation in this paper verify and validate the applicability of the model. Finally, a framework for developing a procedure for retrofit cable design is presented.

Prestressed force loss always occurs in prestressed concrete (loss prestressed). The most common form used in pre-tensile beams is straight tendons and for post-tensile beams are curved tendons. In planning a prestressed concrete bridge structure, the loss of prestressed force must be considered, because the stress on the prestressed concrete tendon decreases continuously over time. The number of factors that are interrelated, for the effectiveness of the design, location of tendons along the spans need to be considered, so that the tensile strength that occurs in the extreme fiber beam is limited or none at all in the cross section. This final project will examine the shape of the PC beam I Girder with 4 tendon setting conditions namely straight tendon cable which is on the neutral axis so that the eccentricity = 0 (condition1), straight tendon cable which is at 1/6 h so that the eccentricity ≠ 0 (condition 2), tendon cable with draped / parabolic shape (condition 3), and tendon condition with harped shape (condition 4). The biggest prestressed loss results were PC I Girder (condition 2) = 395.81 MPa (26.07%), while the smallest prestressed loss is PC I Girder (condition3) = 367.44 MPa (24.2%). Condition 1 and 2 in girder is not suitable for use because it exceeds the value of the allowable stress at the limit of prestressed and deflection permits on girder are safe for each condition.

The profile layout rationality and internal stress structure of a large-section cable tunnel and a cable-laying scheme at splicing locations were studied through full-scale model test. The full scale shield tunnel which the diameter was 6m was built on the ground. The model tests test the displacement of cable bearers, the coupling area between horizontal beam and steel ring, the coupling area between horizontal beam and steel pillar, edge beam and center beam under design loads, and the safety and reliability of an arc steel framing system that supports the cable load inside the cable tunnel during the operation stage were demonstrated. The cable-laying schemes for the cross section and straight-through-type and T-type couplings of a large-section cable tunnel were optimized through experiment on actually laid-out cables. For the section layout of a large-section cable tunnel, it is believed that the double-deck scheme prevails over the single-deck scheme, and such a cable-splicing scheme can meet the cable-laying requirement.

The growth of fission yeast relies on the polymerization of actin filaments nucleated by formin For3p, which localizes at tip cortical sites. These actin filaments bundle to form actin cables that span the cell and guide the movement of vesicles toward the cell tips. A big challenge is to develop a quantitative understanding of these cellular actin structures. We used computer simulations to study the spatial and dynamical properties of actin cables. We simulated individual actin filaments as semiflexible polymers in three dimensions composed of beads connected with springs. Polymerization out of For3p cortical sites, bundling by cross-linkers, pulling by type V myosin, and severing by cofilin are simulated as growth, cross-linking, pulling, and turnover of the semiflexible polymers. With the foregoing mechanisms, the model generates actin cable structures and dynamics similar to those observed in live-cell experiments. Our simulations reproduce the particular actin cable structures in myoVΔ cells and predict the effect of increased myosin V pulling. Increasing cross-linking parameters generates thicker actin cables. It also leads to antiparallel and parallel phases with straight or curved cables, consistent with observations of cells overexpressing α-actinin. Finally, the model predicts that clustering of formins at cell tips promotes actin cable formation.

This paper explores polycrystalline 3C-silicon carbide (poly-SiC) deposited by LPCVD for fabricating flexible ribbon cable interconnects for micromachined neural probes. While doped silicon is used currently, we hypothesized that poly-SiC will provide enhanced mechanical robustness due to SiC’s superior mechanical properties. Paralleling prior work in silicon, forty-two different designs were fabricated from nitrogen-doped poly-SiC films deposited by LPCVD at 900°C using dichlorosilane and acetylene as precursors. The different designs were then tested in bending and twisting modes. Curved beams were found to bend nearly 250% more than straight beams before fracture. Longer beams withstood greater bending and twisting due to greater compliance. Longer and narrower beams generally outperformed shorter beams irrespective of design. Also, doped poly-SiC beams had, on average, breaking angles that were greater than those of identical doped silicon beams by ~50% in bending and ~20% in twisting modes. The paper details the designs studied, describes the fabrication process for the test structures and compares/contrasts the testing and simulation results related to the different designs to identify best design practices.

The theory of geometrical nonlinear analysis is introduced. The sag effect is considered by the multiple-straight truss elements. The unstress length which is modeled the tension force of cable is figured out. Three kind of positions where the new elements are activated on are offered: tangent to old elements, parallel to old elements and original model coordinate, the method of parallel to old elements is used in the construction stages analysis and the method of original model coordinate is used in the construction control analysis. The purpose of construction control analysis for pretensioned structure in this paper is that the architectural configuration should be satisfied after construction control analysis is finished. The procedure of construction control analysis for pretensioned structure is summarized. The computational accuracy and the effectiveness are proven by the example of the cantilever beam with cables.

Beam string structure (BSS), which is a new kind of semi-rigid hybrid system, composed of arch, strut and string, has been developed rapidly in long-span steel structures in recent years. Based on the principle of virtual work and Updated Lagrange, the formulas of geometric nonlinear F.E.M. for spatial beam element, cable element and truss element are derived respectively in this paper. Taking the one-way BSS model of the steel roof in Guangzhou International Convention and Exhibition Center as a computational example by using both linear and nonlinear analysis method, the analytical results show that it is appropriate when adopting the straight truss element with two joints and equivalent elastic modulus to simulate the cable element with small sag. Although the linear analysis can meet the requirement of practical engineering due to its weak nonlinearity of BSS, the nonlinear method is also important to improve the precision theoretically. The conclusions obtained may be helpful for the designers in similar projects.

This paper presents a thermoelastic solution technique for beams with arbitrary quasi-static temperature distributions that create large transverse normal and shear stresses. This technique calculates the stress resultants and centroid displacements along a beam. Then, the stress resultants and temperature distribution are used to calculate the stress distributions on a cross section of the beam. Simple examples demonstrate the numerical efficiency of the proposed technique and the inadequacy of the strength of materials theory to solve these types of problems.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This work presents the application of optimization techniques for the design of hollow core slabs and beams with precast and prestressed straight cable, considering the calculation of both the immediate losses as the time-dependent. For the slabs formulation allows the designer to obtain the optimal dimensions of the height of the panel, the diameters of the cables and the alveoli, and the number of cables. The beams are obtained beam height, diameter and the number of cables. Are still subject to the conditions of service for bending stresses, constructive limitations and failure conditions. Illustrative examples are presented using the Branch and Bound algorithm and Lingo (PLS), further comparison is made between the weight and the cost of the panel, and from the results of the algorithm and sizing Munte tables that follow Brazilian standards. We conclude that the optimal design has many advantages compared to conventional design, methods of discrete variation that best characterize the optimal variables of the problem, restrictions on the normal stresses ELS are crucial in obtaining the optimal dimensions of the structures and lower panels weight does not necessarily represent the lowest cost.
Este trabalho apresenta a aplicação de técnicas de otimização para o dimensionamento de lajes alveolares e vigas com cabo reto pré-moldadas e protendidas, considerando o cálculo tanto das perdas imediatas quanto das dependentes do tempo. Para as lajes, a formulação permite que o projetista obtenha as dimensões ótimas da altura do painel, dos diâmetros dos alvéolos e dos cabos, e do número de cabos. Nas vigas, são obtidas a altura da viga, o diâmetro e o número dos cabos. São, ainda, observadas as condições de serviço para esforços de flexão, limitações construtivas e condições de falha. Exemplos ilustrativos são apresentados usando o algoritmo de Branch and Bounde o Lingo(PLS). São feitos, ainda, comparativos entre o peso e o custo do painel e entre os resultados obtidos pelo algoritmo e tabelas de dimensionamento encontradas na literatura que seguem normas brasileiras. Conclui-se que o projeto ótimo apresenta inúmeras vantagens se comparado ao projeto convencional, que os métodos de variação discreta caracterizam melhor as variáveis ótimas do problema, que as restrições relativas às tensões normais do ELS são determinantes na obtenção das dimensões ótimas das estruturas e que painéis de menor peso não necessariamente representam o menor custo.

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
UNIVERSIDADE FEDERAL DE UBERLÂNDIA
A formulação de um modelo para a análise por elementos finitos, da torção de vigas retas com seção transversal I é apresentada. O modelo de viga isoparamétrico para seções retangulares que não se deformam em seu plano ou fora deste, é estendido para acomodar o empenamento das seções complexas submetidas a carregamentos de torção. Utiliza-se graus de liberdade generalizados na representação do campo de deformações da seção reta e modificações nas relações de compatibilidade geométricas são introduzidas no sentido de acomodar as deformações de cisalhamento devido a rotação da seção. As condições de compatibilidade no engastamento e entre elementos adjacentes devidas a flexão nos flanges são garantidas empregando-se uma técnica de penalidades entre os graus de liberdade de rotação longitudinal no ponto nodal. Implementa-se o modelo numérico demonstrando-se a sua aplicabilidade na representação de problemas de torção linear em vigas retas, com diversas seções, e.g, triangular equilátera, elíptica, retangular, I – simétrica e não simétrica e T.
The formulation of a finite element model for studying the torsion of estraight beams with I-cross section is presented. The isoparametric beam model with rectangular cross sections which do not have deformation in the section plane or out of it, is extended to accommodate the warping of complex cross sections submitted to torsion loadings. The deformation field of the cross section is represented by generalized degrees of freedom and modifications in the original beam geometric compatibility relations were performed to accommodate shear deformations due to section rotation. The compatibility conditions at fixed end and between two connected elements due to the flange bending are assured using a penalty technique to the longitudinal rotation degrees of freedom at the nodal point. The proposed numerical model is implemented and some sample analyses demonstrate its capabilities on the representation of the problem of linear torsion of straight beams with different cross section shapes; e.g, triangular equilateral, elliptic, rectangular, I – symmetric and non symmetric and T section.

Multilayered composites are widespread in load-bearing structures of the aeronautical and wind energy industries. Increasingly, advanced composites are spreading into the mass-market automotive sector, where the lightweight advantages of composites improve structural efficiencies and thereby enable a new generation of electric cars. Composite laminates are mostly employed in thin-walled semi-monocoque structures as the manufacturing processes, such as pre-preg curing and resin infusion, are amenable to this type of construction. However, their imminent diversification to new applications will benefit from extending the range of possible laminate configurations in terms of layer material properties, stacking sequences and laminate thicknesses, as well as the nature of service loading. Such a diversification can add significant complexity when, for example, the layer material properties differ by multiple orders of magnitude or when the composite comprises of relatively thick cross-sections. In case of the former, the structural response is non-intuitive and cannot be modelled adequately using classical lamination theory. The latter adds non-classical effects due to transverse shearing and transverse normal stresses, which are particularly pernicious due to the lack of reinforcing material in the stacking direction and can lead to the delamination of layers. Reliable design of these multilayered structures requires tools for accurate stress analysis that account for these non-classical higher-order effects. Despite offering high fidelity, three dimensional (3D) finite element models are prohibitive for iterative design studies due to their high computational expense. Consequently, a large number of approximate higher-order two dimensional (2D) theories have been formulated over the last decades, with the aim of predicting accurate 3D stress fields while maintaining superior computational efficiency. The majority of these formulations have focused on purely displacement-based approaches that typically require post-processing steps to recover accurate transverse stresses. The work presented here uses the Hellinger-Reissner mixed-variational principle to derive a higher-order 2D equivalent single-layer formulation that predicts variationally consistent 3D stress fields in laminated beams and plates with 3D heterogeneity, i.e. laminates comprised of layers with material properties that differ by multiple orders of magnitude and that also vary continuously in-plane. The formulation is shown to be accurate to within a few percent of 3D elasticity and 3D finite element solutions. A novelty of the present approach is that the computational expense is reduced by basing all stress fields on the same set of unknowns. Furthermore, by enforcing Cauchy's equilibrium equations in the variational statement via Lagrange multipliers, and then solving the ensuing governing equations in the strong form using spectral methods, boundary layers in the 3D stress fields are captured robustly. The present formulation is then used to ascertain the relative effects of transverse shear, transverse normal and zig-zag deformations. By studying non-traditional materials and stacking sequences with pronounced transverse anisotropy, the results presented herein provide physical insight into the governing factors that drive non-classical effects, with the aim of aiding the intuition of structural engineers in preliminary design stages. Finally, to showcase a possible application, the model is applied in an optimisation study that tailors the through-thickness stress fields in a beam in order to reduce the likelihood of delaminations. In the author's opinion, the general formulation presented herein is well-suited for accurate and computationally efficient stress analysis ill industrial applications.

Thesis (M.S.)--Missouri University of Science and Technology, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 31, 2008) Includes bibliographical references (p. 48-49).

Uncertainties in load and system properties play a significant role in reliability analysis of vibrating structural systems. The subject of random vibrations has evolved over the last few decades to deal with uncertainties in external loads. A well developed body of literature now exists which documents the status of this subject. Studies on the influ­ence of system property uncertainties on reliability of vibrating structures is, however, of more recent origin. Currently, the problem of dynamic response characterization of sys­tems with parameter uncertainties has emerged as a subject of intensive research. The motivation for this research activity arises from the need for a more accurate assess­ment of the safety of important and high cost structures like nuclear plant installations, satellites and long span bridges. The importance of the problem also lies in understand­ing phenomena like mode localization in nearly periodic structures and deviant system behaviour at high frequencies. It is now well established that these phenomena are strongly influenced by spatial imperfections in the vibrating systems. Design codes, as of now, are unable to systematically address the influence of scatter and uncertainties. Therefore, there is a need to develop robust design algorithms based on the probabilistic description of the uncertainties, leading to safer, better and less over-killed designs. Analysis of structures with parameter uncertainties is wrought with diffi­culties, which primarily arise because the response variables are nonlinearly related to the stochastic system parameters; this being true even when structures are idealized to display linear material and deformation characteristics. The problem is further com­pounded when nonlinear structural behaviour is included in the analysis. The analysis of systems with parameter uncertainties involves modeling of random fields for the system parameters, discretization of these random fields, solutions of stochastic differential and algebraic eigenvalue problems, inversion of random matrices and differential operators, and the characterization of random matrix products. It should be noted that the mathematical nature of many of these problems is substantially different from those which are encountered in the traditional random vibration analysis. The basic problem lies in obtaining the solution of partial differential equations with random coefficients which fluctuate in space. This has necessitated the development of methods and tools to deal with these newer class of problems. An example of this development is the generalization of the finite element methods of structural analysis to encompass problems of stochastic material and geometric characteristics. The present thesis contributes to the development of methods and tools to deal with structural uncertainties in the analysis of vibrating structures. This study is a part of an ongoing research program in the Department, which is aimed at gaining insights into the behaviour of randomly parametered dynamical systems and to evolve computational methods to assess the reliability of large scale engineering structures. Recent studies conducted in the department in this direction, have resulted in the for­mulation of the stochastic dynamic stiffness matrix for straight Euler-Bernoulli beam elements and these results have been used to investigate the transient and the harmonic steady state response of simple built-up structures. In the present study, these earlier formulations are extended to derive the stochastic dynamic stiffness matrix for a more general beam element, namely, the curved Timoshenko beam element. Furthermore, the method has also been extended to study the mean and variance of the stationary response of built-up structures when excited by stationary stochastic forces. This thesis is organized into five chapters and four appendices. The first chapter mainly contains a review of the developments in stochas­tic finite element method (SFEM). Also presented is a brief overview of the dynamics of curved beams and the essence of the dynamic stiffness matrix method. This discussion also covers issues pertaining to modeling rotary inertia and shear deformations in the study of curved beam dynamics. In the context of SFEM, suitability of different methods for modeling system uncertainties, depending on the type of problem, is discussed. The relative merits of several schemes of discretizing random fields, namely, local averaging, series expansions using orthogonal functions, weighted integral approach and the use of system Green functions, are highlighted. Many of the discretization schemes reported in the literature have been developed in the context of static problems. The advantages of using the dynamic stiffness matrix approach in conjunction with discretization schemes based on frequency dependent shape functions, are discussed. The review identifies the dynamic analysis of structures built-up of randomly parametered curved beams, using dynamic stiffness matrix method, as a problem requiring further research. The review also highlights the need for studies on the treatment of non-Gaussian nature of system parameters within the framework of stochastic finite element analysis and simulation methods. The problem of deterministic analysis of curved beam elements is consid­ered first. Chapter 2 reports on the development of the dynamic stiffness matrix for a curved Timoshenko beam element. It is shown that when the beam is uniformly param-etered, the governing field equations can be solved in a closed form. These closed form solutions serve as the basis for the formulation of damping and frequency dependent shape functions which are subsequently employed in the thesis to develop the dynamic stiffness matrix of stochastically inhomogeneous, curved beams. On the other hand, when the beam properties vary spatially, the governing equations have spatially varying coefficients which discount the possibility of closed form solutions. A numerical scheme to deal with this problem is proposed. This consists of converting the governing set of boundary value problems into a larger class of equivalent initial value problems. This set of Initial value problems can be solved using numerical schemes to arrive at the element dynamic stiffness matrix. This algorithm forms the basis for Monte Carlo simulation studies on stochastic beams reported later in this thesis. Numerical results illustrating the formulations developed in this chapter are also presented. A satisfactory agreement of these results has been demonstrated with the corresponding results obtained from independent finite element code using normal mode expansions. The formulation of the dynamic stiffness matrix for a curved, randomly in-homogeneous, Timoshenko beam element is considered in Chapter 3. The displacement fields are discretized using the frequency dependent shape functions derived in the pre­vious chapter. These shape functions are defined with respect to a damped, uniformly parametered beam element and hence are deterministic in nature. Lagrange's equations are used to derive the 6x6 stochastic dynamic stiffness matrix of the beam element. In this formulation, the system property random fields are implicitly discretized as a set of damping and frequency dependent Weighted integrals. The results for a straight Timo- shenko beam are obtained as a special case. Numerical examples on structures made up of single curved/straight beam elements are presented. These examples also illustrate the characterization of the steady state response when excitations are modeled as stationary random processes. Issues related to ton-Gaussian features of the system in-homogeneities are also discussed. The analytical results are shown to agree satisfactorily with corresponding results from Monte Carlo simulations using 500 samples. The dynamics of structures built-up of straight and curved random Tim-oshenko beams is studied in Chapter 4. First, the global stochastic dynamic stiffness matrix is assembled. Subsequently, it is inverted for calculating the mean and variance, of the steady state stochastic response of the structure when subjected to stationary random excitations. Neumann's expansion method is adopted for the inversion of the stochastic dynamic stiffness matrix. Questions on the treatment of the beam characteris­tics as non-Gaussian random fields, are addressed. It is shown that the implementation of Neumann's expansion method and Monte-Carlo simulation method place distinc­tive demands on strategy of modeling system parameters. The Neumann's expansion method, on one hand, requires the knowledge of higher order spectra of beam properties so that the non-Gaussian features of beam parameters are reflected in the analysis. On the other hand, simulation based methods require the knowledge of the range of the stochastic variations and details of the probability density functions. The expediency of implementing Gaussian closure approximation in evaluating contributions from higher order terms in the Neumann expansion is discussed. Illustrative numerical examples comparing analytical and Monte-Carlo simulations are presented and the analytical so­lutions are found to agree favourably with the simulation results. This agreement lends credence to the various approximations involved in discretizing the random fields and inverting the global dynamic stiffness matrix. A few pointers as to how the methods developed in the thesis can be used in assessing the reliability of these structures are also given. A brief summary of contributions made in the thesis together with a few suggestions for further research are presented in Chapter 5. Appendix A describes the models of non-Gaussian random fields employed in the numerical examples considered in this thesis. Detailed expressions for the elements of the covariance matrix of the weighted integrals for the numerical example considered in Chapter 5, are presented in Appendix B; A copy of the paper, which has been ac­cepted for publication in the proceedings of IUTAM symposium on 'Nonlinearity and Stochasticity in Structural Mechanics' has been included as Appendix C.

AbstractLinear accelerators (linacs) use alternating radiofrequency (RF) electromagnetic fields to accelerate charged particles in a straight line. Linacs were invented about 95 years ago and have seen many significant technical innovations since. A wide range of particle beams have been accelerated with linacs including beams of electrons, positrons, protons, antiprotons, and heavy ions. Linac parameter possibilities include pulsed versus continuous wave, low and high beam powers, low and high repetition rates, low transverse emittance beams, short bunches with small energy spreads, and accelerated multiple bunches in a single pulse. The number of linacs around the world has grown tremendously with thousands of linacs in present use, many for medical therapy, in industry, and for research and development in a broad spectrum of scientific fields. Researchers have developed accelerators for scientific tools in their own right, being awarded several Nobel prizes. Moreover, linacs and particle accelerators in general have enabled many discovery level science experiments in related fields, resulting in many Nobel prizes as well.

Loop formation may occur in cables, ropes, and also risers — flexible pipes or umbilical cables — used for offshore exploitation. The phenomenon occurs when there is enough torsion moment in the line and also a low tension condition or, even in the cases of cable slack (almost zero tension) with some torsion moment. Many references discuss about the loop formation prediction in different conditions, but mostly for the cases of an initial straight cable (rope or riser) which is usually represented by a beam. The problem of the loop formation in a catenary riser including the nonlinear contact with the seabed is very important, once during the riser installation in some conditions a low tension combined with torsion moment can lead to the loop formation, which is undesirable. There is a necessity of a better understanding of this theme. The present work explores the loop formation in catenary risers comparing the results of the static and the dynamic predictions, showing an asymptotic tendency from the dynamics to the statics. For that study, geometrically-exact nonlinear beam models were employed in the statics and in dynamics, leading to very realistic loop formation predictions.

<p>This paper presents design and launching of the railways crossing in Bari. The bridge is made up of ten straight spans, 50 + 50 + 50 + 50 + 45 + 112.5 + 112.5 + 66 + 38.8 + 51.2 m, for a total length of 626 m. The longest spans are a cable-stayed bridge with a 70 m high steel pylon, Y shaped, 60° rotated in respect to the deck axis. The deck, supported by 30 stays about every 15 m, has a cross section 25.5m wide, sub-divided in two carriageways of 8.5 m each, separated by a central median of 2.5 m in width. The height of the beam is equal to 2.5 m and the slab has a thickness of 30 cm. Design, construction and launching choices will be described below.</p>

This paper introduces a parametric beam model for describing the kinematics and elastic properties of ortho-planar compliant beams subject to specific buckling loads. This model uses an approach similar to the Pseudo-Rigid-Body Model but differs that in a key parameter, the characteristic radius factor, is not a constant, but a rational function of the moment. The rational function coefficients are determined by least squares, along with the statistical significance of the coefficients. Results are calculated for straight beams for two cases: a vertical displacement and a horizontal displacement.

Cable sag can have significant effects on the cable length computation in a cable-suspended robot and this is more pronounced in large-scale outdoor systems. This requires modeling the cable as a catenary instead of an approximated straight-line model. Furthermore, when there is actuation redundancy involved, the modeling and simulation of the system becomes much more complex, requiring optimizing routines to solve the problem. A cable-sag-compensated (catenary) model was implemented in simulation for an example large outdoor cable-suspended robot system to solve the coupled kinematics and statics problems. This involved optimization of cable tensions and finding the errors involved in the cable length. A comparative analysis between the straight-line and cable sag model is presented, the main contribution of this paper. Based on the qualitative and quantitative results obtained, recommendations were made on the choice of model and solution methodologies.

The purpose of this study is to investigate the nonlinear effect of gravity on the free vibration of a cable against a straight obstacle. The cable model is expressed in terms of nonlinearly coupled transverse and axial displacements. The penalty method is used to simulate the obstacle, which is equivalent to inserting a stiff elastic foundation. The first symmetric frequencies are obtained when the depth of the obstacle is 1/2 and 1/3 of the initial transverse displacement. The effects of varying amplitude and equilibrium curvature are investigated.

Although there have been significant efforts in harvesting environmental energy, our environment is still full of wasted and unused energy. As clean, ubiquitous and sustainable energy source, acoustic energy is one of the wasted energies and is abundant in our life. Therefore, it is of great interest to investigate acoustic energy harvesting mechanism as an alternative to existing energy harvesters. In this study, in order to harvest acoustic energy, piezoelectric cantilever beams are placed inside a quarter-wavelength straight-tube resonator. When the straight-tube resonator is excited by an incident wave at its acoustic eigenfrequency, an amplified acoustic resonant wave is developed inside the tube and drives the vibration motion of the piezoelectric beams. The piezoelectric beams have been designed to have the same structural eigenfrequency as the acoustic eigenfrequency of the tube resonators to maximize the amount of the harvested energy. With a single beam placed inside the tube resonators, the harvested voltage and power become the maximum near the tube open inlet where the acoustic pressure gradient is at the maximum. As the beam is moved to the tube closed end, the voltage and power gradually decrease due to the decreased acoustic pressure gradient. Multiple piezoelectric beams have been placed along the centerline of the tube resonators in order to increase the amount of harvested energy. Due to the interruption of acoustic air particle motion caused by the beams, it is found that placing piezoelectric beams near the closed tube end is not beneficial. The output voltage of the piezoelectric beams increases linearly as the incident sound pressure increases.