Search

The thermal response in paper has been studied by thermography. It was observed that an inhomogeneous deformation pattern arose in the paper samples during tensile testing. In the plastic regime a pattern of warmer streaks could be observed in the samples. On the same samples digital image correlation (DIC) was used to study local strain fields. It was concluded that the heat patterns observed by thermography coincided with the deformation patterns observed by DIC. Because of its fibrous network structure, paper has an inhomogeneous micro-structure, which is called formation. It could be shown that the formation was the cause of the inhomogeneous deformations in paper. Finite element simulations was used to show how papers with different degrees of heterogeneity would deform. Creped papers, where the strain at break has been increased, were analysed. For these paper it was seen that an overlaid compaction of the paper was created during the creping process. During tensile testing this was recovered as the paper network structure was strained. [ABSTRACT FROM AUTHOR]

The article analyses the effects of paper moisture content on energy absorbed during its tensile testing in the range of moisture equilibrium obtained during paper air conditioning at a temperature of 23 °C. To predict changes in breaking energy caused by changes in moisture content, two calculation methods were proposed. The methods were verified on the basis of laboratory tests and calculation results, and their practical usefulness was confirmed. [ABSTRACT FROM AUTHOR]

This article describes a new method for evaluation of radial crush strength of paper cores. Based on the theory of multilayered composites, a mathematical model has been developed to calculate the value of destructive force during radial crushing of spirally shaped paper cores whose layers are made of different materials. To start calculations, it is necessary to have geometry parameters of the cores, Young's modulus and SCT of an individual component layers. [ABSTRACT FROM AUTHOR]

In this paper, an efficient computational framework for the full-wave design by optimization of complex microwave passive devices, such as antennas, filters, and multiplexers, is described. The framework consists of a computational engine, a 3D object modeler, and a graphical user interface. The computational engine, which is based on a finite element method with curvilinear higher-order tetrahedral elements, is coupled with built-in or external gradient-based optimization procedures. For speed, a model order reduction technique is used and the gradient computation is achieved by perturbation with geometry deformation, processed on the level of the individual mesh nodes. To maximize performance, the framework is targeted to multicore CPU architectures and its extended version can also use multiple GPUs. To illustrate the accuracy and high efficiency of the framework, we provide examples of simulations of a dielectric resonator antenna and full-wave design by optimization of two diplexers involving tens of unknowns, and show that the design can be completed within the duration of a few simulations using industry-standard FEM solvers. The accuracy of the design is confirmed by measurements. [ABSTRACT FROM AUTHOR]

The mechanical response of three different structural core sandwich panels in out-of-plane compression and shear has been analyzed. Specific core shapes examined are arc-tangent, wavy trapezoidal and hemispherical. Unit cells consisting of representative elements of the core attached to face sheets were selected for analysis. Both face sheets and core were assumed made from paper. Finite element analysis employing large deformation and rotations and orthotropic elastic–plastic behavior was used. The results show that the arc-tangent and trapezoidal cores are prone to collapse by extensive bending and buckling, whereas the hemispherical core behaved more stably in compression and shear. Core sheets with a hemispherical shape were prepared from copy paper sheets in a specially designed forming machine. Sandwich test specimens were prepared from this core and tested in out-of-plane compression, and the load-displacement response was compared to predictions from finite element simulations. The experimental and finite element results were consistent. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive analysis of collision and impact problems' numerical solutions, focusing on geometric, contact, and material nonlinearities, all essential in solving large deformation problems during a collision. The initial discussion revolves around the stress and strain of large deformation during a collision, followed by explanations of the fundamental finite element solution method for addressing such issues. The hourglass mode's control methods, such as single-point reduced integration and contact-collision algorithms are detailed and implemented within the finite element framework. The paper further investigates the dynamic response and failure modes of Reinforced Concrete (RC) members under asymmetrical impact using a 3D discrete model in ABAQUS that treats steel bars and concrete connections as bond slips. The model's validity was confirmed through comparisons with the node-sharing algorithm and system energy relations. Experimental parameters were varied, including the rigid hammer's mass and initial velocity, concrete strength, and longitudinal and stirrup reinforcement ratios. Findings indicated that increased hammer mass and velocity escalated RC member damage, while increased reinforcement ratios improved impact resistance. Contrarily, increased concrete strength did not significantly reduce lateral displacement when considering strain rate effects. The study also explores material nonlinearity, examining different materials' responses to collision-induced forces and stresses, demonstrated through an elastic rod impact case study. The paper proposes a damage criterion based on the residual axial load-bearing capacity for assessing damage under the asymmetrical impact, showing a correlation between damage degree hammer mass and initial velocity. The results, validated through comparison with theoretical and analytical solutions, verify the ABAQUS program's accuracy and reliability in analyzing impact problems, offering valuable insights into collision and impact problems' nonlinearities and practical strategies for enhancing RC structures' resilience under dynamic stress. [ABSTRACT FROM AUTHOR]

The propulsion system for an aircraft is one of its most crucial systems; therefore, its reliable work must be ensured during all operational conditions and regimes. Modern materials, techniques and methods are used to ensure this goal; however, there is still room for improvement of this complex system. The proposed manuscript describes a progressive approach for the mechanical properties prediction of the turbine section during jet engine operation using an artificial neural network, and it illustrates its application on a small experimental jet engine. The mechanical properties are predicted based on the measured temperature, pressure and rpm during the jet engine operation, and targets for the artificial neural network are finite element analyses results. The artificial neural network (ANN) is trained using training data from the experimental measurements (temperatures, pressure and rpm) and the results from finite element analyses of the small experimental engine turbine section proposed in the paper. The predicted mechanical stress by ANN achieved high accuracy in comparison to the finite element analyses results, with an error of 1.38% for predicted mechanical stress and correlation coefficients higher than 0.99. Mechanical stress and deformation prediction of the turbine section is a time-consuming process when the finite element method is employed; however, the method with artificial neural network application presented in this paper decreased the solving time significantly. Mechanical structural analyses performed in ANSYS software using finite element modeling take around 30–40 min for one load step. In contrast, the artificial neural network presented in this paper predicts the stress and deformation for one load step in less than 0.00000044 s. [ABSTRACT FROM AUTHOR]

The pipe curtain structure method (PSM) is a novel construction method to control ground deformation strictly. Compared with the traditional pipe-roofing and pipe jacking method, the connection between pipes in large spacings using PSM is widely acknowledged as a unique construction procedure. Further study on this connection procedure is needed to resolve similar cases in that the pipes are inevitably constructed on both sides of existing piles. Cutting the steel plate during the connection procedure is the first step, which is crucial to control the safety and stability of the surrounding environment and existing structures. The deformation mechanism and limit support pressure of the cutting steel plate during the connection between pipes in large spacings are studied in this paper, relying on the undercrossing Yifeng gate tower project of Jianning West Road River Crossing Channel in Nanjing, China. A modified 3D wedge-prism failure model is proposed using the 3D discrete element method. Combined with Terzaghi loose earth pressure theory and the limit equilibrium theory, the analytical solutions for the limit support pressure of the excavation face of the cutting steel plate are derived. The modified 3D wedge-prism failure model and corresponding analytical solutions are categorised into two cases: (a) unilateral cutting scheme, and (b) bilateral cutting scheme. The analytical solutions for the two cases are verified from the numerical simulation and in-situ data and compared with the previous solutions. The comparative analysis between the unilateral and bilateral cutting schemes indicates that the bilateral cutting scheme can be adopted as a priority. The bilateral cutting scheme saves more time and induces less ground deformation than the unilateral one due to the resistance generated from the superimposed wedge. In addition, the parametric sensitivity analysis is carried out using an orthogonal experimental design. The main influencing factors arranged from high to low are the pipe spacing, the cutting size, and the pipe burial depth. The ground deformation increases with the increased cutting size and pipe spacing. The pipe burial depth slightly affects the ground deformation if the other two factors are minor. Cutting steel plates in small sizes, excavating soil under low disturbance, and supporting pipes for high frequency can effectively reduce the ground surface subsidence. [ABSTRACT FROM AUTHOR]

A steel brace is effective to retrofit old reinforcement concrete (RC) buildings by increasing the horizontal load capacity of structures. However, concrete cracks that easily occur in the surrounding RC members under tension initiate early strength degradation, so this research aimed to develop a new self-centering brace (SCB) with the compression-only capacity such that no tension force is developed in the brace or to the adjoining RC members. Original SCBs have been developed to reduce the residual deformation of structures with a symmetrically flag-shaped hysteretic response. By altering the force transfer mechanism in the original SCB, a compression-only self-centering brace (C-SCB) can be developed under a symmetrically reversed cyclic loading, providing an alternative for the RC building retrofit. This paper first introduces the mechanics and deformation mechanism of the proposed C-SCB. A test program is then conducted on the cyclic tests of a buckling-restrained energy dissipating bar (EDB) to evaluate the energy dissipation. A 3,695-mm-long C-SCB is composed of posttensioning high-strength steel tendons, steel compression members, and buckling-restrained EDBs for the energy dissipation. The C-SCB in tests showed a good compression-only self-centering capability up to an axial displacement of 31 mm, with a maximum axial force of 1,530 kN. No damage of the steel tendons, compression members, or EDBs was found after three phase tests. Finite element analysis further validated the compression-only hysteretic response and mechanics of the C-SCB in a symmetrically reversed cyclic loading. [ABSTRACT FROM AUTHOR]

Inclusions are important phases affecting material properties in complicated ways. In this paper, a quantitative study of the addition of HfO2 inclusions to DZ125 nickel-based superalloys was performed. Experimental results showed that the introduction of HfO2 inclusions caused a loss of strength and ductility. The carbide morphology also changed significantly from skeletal-shaped to block-shaped, resulting in a remarkable discrepancy in the fracture behavior under quasi-in-situ tensile testing. The SEM dynamic observations showed that cracks were initiated from the skeletal carbides and almost failed to propagate into the matrix. In contrast, the damage behavior of block-shaped carbides also involved internal cracking but with a tendency to form interconnected microcracks during propagation. A crystal plasticity finite element model (CPFEM) method was further developed to study the stress/strain behavior during the deformation process, considering the crystal orientations and microstructure morphologies from the EBSD data. Those elastoplastic parameters were determined through nanoindentation experiments. Simulation results verified that blocky carbides produced a pronounced strain concentration at the interface of the carbides and matrix, thereby increasing the tendency of crack formation. This paper provides a fundamental understanding of the role of inclusions in material recycling applications. [ABSTRACT FROM AUTHOR]

Engineers pay more and more attention to the economic benefits of foundation pit engineering. At present, the optimal design of the foundation pit supporting structure mainly focuses on strength and functional design, and there is no mature theoretical design method for deformation control. In this paper, a method for calculating the overall deformation of a foundation pit supporting structure based on the principle of minimum potential energy is proposed. Based on this method, the optimal design of the foundation pit of Guangzhou Baiyun District Comprehensive Transportation Hub Metro Station is realized. The deformation calculation results and optimization design scheme are validated by finite element numerical simulation and field monitoring data. The results show that the proposed theoretical algorithm predicts the pile deformation curves better than the finite element method, suggesting the proposed theoretical method is reasonable and the optimization scheme of the retaining pile is feasible. In the optimized design, the deformation of the foundation pit retaining pile is controlled by its push-back effect. The proposed deformation calculation method can realize the overall deformation calculation of the foundation pit supporting structure. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to enhance the energy absorption (EA) of honeycombs in the out-of-plane direction. Inspired by the Koch fractal, a fractal hexagonal honeycomb (FHH) is presented in this paper. In our study, we use Abaqus/Explicit to build a finite element model of the honeycomb, through which we conduct a series of studies on the performance of this honeycomb. Initially, we compare the mechanical properties and deformation modes of the FHH with those of a conventional hexagonal honeycomb. The results demonstrate notable improvements in crashworthiness metrics for the FHH, including a 52% increase in specific EA, a 45% enhancement in crushing load efficiency (CLE), and an 8% reduction in peak crushing force (PCF) compared to the conventional counterpart. Subsequently, this paper investigates the fractal arc honeycomb and evaluates the effect of the center angle on mechanical properties by varying its value. Furthermore, the mechanical properties of layered honeycomb and fractal honeycomb structures with different wall thicknesses are systematically examined. In the last section, we explore the theoretical analysis of the fractal-hexagonal honeycomb and find that the results of the theoretical analysis are in good agreement with those of the simulation, indicating that the experimental simulation results are reliable. Overall, the findings of this study offer valuable insights for the innovative design of hexagonal honeycomb structures, providing a reference for future advancements in this field. [ABSTRACT FROM AUTHOR]

It is difficult for the existing Burgers model to accurately depict the off-axis cyclic drawing process of woven coatings. In this paper, the mechanical deformation of woven PVC (polyvinyl chloride)-coated film at different temperatures is investigated. One-dimensional (1D) and two-dimensional (2D) constitutive models were established to characterize cyclic deformation processes. The 1D model is an improved Burgers model. The effects of the time dependence of the viscosity coefficient and the ratio of elastic to viscous deformation are considered simultaneously. The accuracy of the 1D model for predicting the cyclic nonlinear deformation at different temperatures and loading rates is improved. The 2D model is a nonlinear orthotropic model using polynomials. On the basis of the single-objective genetic algorithm, the inverse algorithm is used to obtain the shear polynomial coefficients in the tension phase and the shear modulus in the unloading phase, which circumvents performing the difficult shear test. UMAT subroutines of off-axis stretching and off-axis cyclic stretching are written separately. The intelligent inverse algorithm program consists of a single-objective genetic algorithm program, a finite element parametric modelling program, and a UMAT subroutine. The simulation results are compared with the off-axis cyclic tensile test data to validate the effectiveness and accuracy of the proposed 2D model for the analysis of the woven PVC-coated films in the tension–shear coupling state. [ABSTRACT FROM AUTHOR]

This paper focuses on the composite design with fibres loaded in the longitudinal direction as well as orientated at some certain angles. The study uses Bombyx Mori Moth Silk (BMM Silk) as fibres and vinyl ester as matrix material. The two sorts of composites having cross ply and angle ply laminate were considered for deformation study using the finite element analysis. According to the ASTM D 3039 testing standard, the tensile test was carried out to design and composite study of their occurred deformation. The rule of mixture was employed in order to evaluate the elastic constants of the prepared orthotropic composite laminate along the fibre direction and the evaluation of orthogonal stresses in transverse direction was carried out using the finite element procedure. The maximum orthogonal stress value of cross ply and angle ply was found to be 44.902 and 47.779 MPa, respectively. Also, the deformation occurred for both laminates was found to be of 0.083603 and 0.076428. This concludes that the deformation occurrence is more in case of angle ply and is less in cross ply laminates. [ABSTRACT FROM AUTHOR]

Summary: The material point method is a versatile technique which can be used to solve various types of solid mechanics problems, especially those involving large deformations. However, the capability of the material point method to track a load‐displacement response can deteriorate once a limit point, such as snap‐through or snap‐back, in the response is encountered. One way of overcoming this is to use path following techniques, such as an arc‐length method. This technique is well established in finite element analysis but not within any material point method formulation. This paper provides for the first time an arc‐length controlled implicit, quasi‐static material point method. The modifications to the standard arc‐length scheme to allow for the stable execution of an arc‐length solver within the material point method are detailed. The capability of the material point‐based arc‐length method is demonstrated through a number of problems, which include linear elastic, non‐linear elastic, linear elastic‐perfectly plastic and linear elastic‐plastic softening material behaviour under large deformations. The techniques presented in this paper are essential for arc‐length techniques to be applied effectively to the material point method and the combination of these techniques makes the method suitable for new problems that cannot be solved with existing implicit material point approaches. [ABSTRACT FROM AUTHOR]

This paper presents the analysis by the finite element method of the tensions and deformations produced in the mechanized support beams. The finite element method allows the analysis of physical phenomena that can be described with the help of mathematical models made up of systems of differential equations with initial and boundary conditions. From the results obtained in this paper, it was observed that the asymmetries with the greatest influence are those with respect to the vertical-longitudinal plane of the mechanized support [ABSTRACT FROM AUTHOR]

With the popularized application of underground cable tunnels in China, various structural defects such as cracking, deforming and material deteriorating also emerge. In cable tunnels that have been poorly maintained for a long time, there is always a coexistence of several kinds of defects, and with the current methods of monitoring, it is difficult to identify the major defect affecting the load-carrying capacity and resolve it. However, the finite element method (FEM) can better solve this problem by analyzing the effect of a single defect parameter separately. In this paper, four different types of cable tunnels, namely the circular, rectangular, arched and trenched sectional tunnels, are modelled and analyzed with FEM. Defect parameters, including crack dimensions and concrete deterioration, are considered as variables, which are controlled and studied respectively. The results of the simulation indicate that the impact of crack propagation on the residual-bearing capacity of cable tunnels is much larger than that of concrete deterioration, especially the deepening of cracks. Works in this paper have the potential to be further referenced for cable-tunnel structure estimation and defect prevention. [ABSTRACT FROM AUTHOR]

This paper presents the results of modelling research concerned with the technological process of the cold bending of a pipe. Stress and plastic strain studies are carried out using the finite element method (FEM) on a thick-walled pipe and various shapes of bending form. The results of the research are benchmarked in terms of the correctness of the implementation of the bending process, including the change in the pipe outside diameter and wall thickness. The level of ovalisation of the cross-section in the bending pipe is used as the primary criterion for assessing the correctness of the bending process. The results show that the most favourable properties in terms of minimising the ovalisation of the pipe cross-section are provided by the use of a bending form with a trapezoidal shape. [ABSTRACT FROM AUTHOR]

Structures composed of aviation aluminium alloys, characterized by their limited rigidity and thin-walled configurations, frequently exhibit deformation after processing. This paper presents an investigation into T-shaped components fabricated from pre-stretched 7075-T7451 aviation aluminium alloy sheets, examining the effects of residual stress and the geometrical parameters of T-shaped components on their deformational behavior. A semi-analytical model, developed to elucidate the bending deformation of T-shaped components subjected to residual stress, was validated through finite element analysis and empirical cutting experiments. The experimental results revealed that the bending deformation deflection of the T-shaped specimen was 0.920 mm, deviating by a mere 0.011 mm from the prediction provided by the semi-analytical model, resulting in an inconsequential error margin of 1.2%. This concordance underscores the precision and accuracy of the semi-analytical model specifically designed for T-shaped components. Moreover, the model's simplicity and ease of application make it an effective tool for predicting the bending deformation of thin-walled T-shaped components under a range of residual stresses and dimensional variations, thereby demonstrating its significant utility in engineering applications. [ABSTRACT FROM AUTHOR]

Integrated heating and mechanical rolling forming (IHMRF) has recently been introduced for manufacturing complex curvature hull plates. It fabricates the target curved plate by sequential loading along the multipath. Accurate and efficient prediction of the deformation of the plate is the basis for developing the process planning and ensuring the quality of the forming. The inherent-strain method is ideal for this purpose, but its prediction accuracy needs to be improved. This paper proposes a multipath process-based inherent-strain method (MPISM), which considers the effect of the sequential loading process of the multipath on plate deformation. First, the effect of loading paths near the plate edge was investigated, which in turn clarified the rationale for obtaining the inherent strain only in the plate center. Secondly, a strain correction strategy was established by analyzing the variation pattern of the inherent strain caused by the crossing or proximity of the previous path and the subsequent path. This allowed the effects of the loading process to be taken into account in the elastic analysis. Based on the plate-and-shell theory, the idea of an equivalent inherent strain distribution is also presented. This makes the loading of inherent strains more accurate in the elastic finite-element model. MPISM predictions and experimental results show good agreement. Compared with the thermo-elastic–plastic finite element method, the MPISM substantially improves efficiency while maintaining accuracy. Compared with the original inherent-strain method, the MPISM is more accurate in terms of deformation magnitude prediction. [ABSTRACT FROM AUTHOR]

In micro-LED chip repair, a nanopositioner is commonly used to adjust the positioning of the LED chip. However, during the bonding process, the heat generated can cause the positioning system to deform, leading to inaccurate alignment and poor-quality chip repair. To solve this issue, a novel flexible connection structure has been proposed that can eliminate thermal deformation. The principle of this novel flexible connection structure is that the thermal distortion self-elimination performance is achieved via three flexible connection modules (FCM) so that the thermal stress is automatically eliminated. First, the paper introduces the principle of thermal deformation elimination, and then the design and modeling process of the proposed structure are described. A heat transfer model is then developed to determine how temperature is distributed within the structure. A thermal deformation model is established, and the size of the FCM is optimized using a genetic algorithm (GA) to minimize the thermal deformation. Finite element analysis (FEA) is used to simulate and evaluate the thermal distortion self-elimination performance of the optimized mechanism. Finally, experiments are conducted to verify the reliability and accuracy of the simulation results. The simulations and experiments show that the proposed structure can eliminate more than 38 % of the thermal deformation, indicating an excellent thermal deformation self-eliminating capability. [ABSTRACT FROM AUTHOR]

Cutting toolholders, with designed in-built compliant mechanisms, are frequently used for machining microfeatures. In this paper, compliant structures are designed using trusses as they exhibit a superior strength-to-weight ratio. Systematically stacked two-stage truss structures along with flexure hinges are designed to yield the desired precise cutting motion. The materially reduced efficient design amplifies the output force and greatly assists in overcoming cutting resistance during machining. The characteristics of the designed compliant tool holder are analysed by considering the output force and displacement for a given input. Both mathematical modelling to determine the force and finite element analysis to identify the critical stress regions when subjected to a prescribed input displacement are presented. As part of dynamic analysis, modal analysis and harmonic response studies were performed to determine how the trussed compliant structure deforms when subjected to dynamic loadings. The designed tool holder was additively manufactured using functionally rigid polyamide-12-glass-bead (PA12-GB) material. The performance of the developed cutting tool holder is then verified by machining radially graded surfaces following which, the machining results are presented in this paper. [ABSTRACT FROM AUTHOR]

In order to reduce the machining deformation of thin-walled parts during milling, a non-uniform allowance planning method for thin-walled parts based on the workpiece deformation constraint with the idea of adding materials in reverse material removal sequence is proposed in this paper. This method does not require accurate deformation prediction and extensive experiments compared to traditional error compensation methods. It strives to maximize the allowance to enhance the stiffness of the in-process workpiece. First, a cutting force threshold calculation method is proposed according to the finite element method. The cutting force threshold at different positions is calculated by obtaining the local stiffness characteristics at the cutter-contact point under the constraint of allowable deformation. And then, the maximum machining allowance at the cutter-contact point is calculated depending on the cutting force model. Considering that the stiffness of the workpiece is position-dependent and affected by material removal, the stiffness of the workpiece is updated by adding elements in the reverse cutting direction, and the finishing stock is obtained by surface fitting. Experimental results show that compared with the traditional uniform allowance method, the error of the proposed method is reduced by about 83%, which can effectively reduce the deformation and improve the machining accuracy. [ABSTRACT FROM AUTHOR]

In the present work, a displacement-based high-order shear deformation theory is introduced for the static response of functionally graded plates. The present theory is variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. By dividing the transverse displacement into the bending and shear parts and making further assumptions, the number of unknowns and equations of motion of the present theory is reduced a and hence makes them simple to use. The material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of material constituents. The equilibrium equations of a functionally graded plate are given based on the higher order shear deformation theory. The numerical results presented in the paper are demonstrated by comparing the results with solutions derived from other higher-order models found in the literature and the present numerical results of Finite Element Analysis (FEA). In the numerical results, the effects of the grading materials, lay-up scheme and aspect ratio on the normal stress, shear stress and static deflections of the functionally graded sandwich plates are presented and discussed. It can be concluded that the proposed theory is accurate, elegant and simple in solving the problem of the bending behavior of functionally graded plates. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model for arterial dissection based on a novel hypothesis proposed by a surgeon, Axel Haverich, see Haverich (Circulation 135(3):205–207, 2017. https://doi.org/10.1161/circulationaha.116.025407). In an attempt and based on clinical observations, he explained how three different arterial diseases, namely atherosclerosis, aneurysm and dissection have the same root in malfunctioning Vasa Vasorums (VVs) which are micro capillaries responsible for artery wall nourishment. The authors already proposed a mathematical framework for the modeling of atherosclerosis which is the thickening of the artery walls due to an inflammatory response to VVs dysfunction. A multiphysics model based on a phase-field approach coupled with mechanical deformation was proposed for this purpose. The kinematics of mechanical deformation was described using finite strain theory. The entire model is three-dimensional and fully based on a macroscopic continuum description. The objective here is to extend that model by incorporating a damage mechanism in order to capture the tearing (rupture) in the artery wall as a result of micro-injuries in VV. Unlike the existing damage-based model of the dissection in the literature, here the damage is driven by the internal bleeding (hematoma) rather than purely mechanical external loading. The numerical implementation is carried out using finite element method (FEM). [ABSTRACT FROM AUTHOR]

Heat input is a crucial parameter in the process of welding thin plates. It has a direct impact on the quality of the weld and the degree of deformation caused during welding. This study investigates the impact of heat input on the deformation of a thin bending plate and its weld zone using the thermoelastic–plastic finite element method. The accuracy of the model is ascertained using the non-contact inspection method utilizing digital image correlation technology. The welding deformation patterns of thin bending plates with a radius of 500 mm were analyzed at various welding heat inputs ranging from 173 J/mm to 435 J/mm. The results indicate that the finite element prediction model proposed in this paper is highly accurate. It has been observed that, under this range of thermal input, the thin bent plates undergo saddle deformation. By examining the correlation between heat input and the maximum deformation outside of the plane, it has been determined that a heat input of at least 50 J/mm is required for the thin bending plate to experience out-of-plane deformation. Additionally, as the level of heat input increases, so too does the out-of-plane deformation of the thin bending plate. After the completion of the welding cooling process, the transverse shrinkage at the weld seam of the thin bend plate is twice that of the longitudinal shrinkage. However, the transverse deformation of the bend plate is not significantly different from the longitudinal deformation. [ABSTRACT FROM AUTHOR]

Summary: Due to creep and shrinkage of concrete, the long‐term structural deformation is one of the hottest topics in the study of super high‐rise structures. For the frame–eccentrical core tube structure, its long‐term deformation includes both vertical deformation and obvious horizontal deformation, which will have an inevitable influence on the structural verticality. The horizontal deformation and its formation mechanism in frame–eccentrical core tube structure are studied in this paper. Based on the finite element software ETABS, a refined finite element model combining with the time‐dependent material model of concrete is established base on a subsistent structure. According to the actual construction conditions, construction analysis is conducted, and the construction deformation and the long‐term deformation after completion are subsequently studied. Based on the results of construction analysis, the effects of elastic modulus, creep, and shrinkage on structural horizontal deformation are analyzed; furthermore, the horizontal deformation characteristics of different structural members in different periods are compared. The results show that the horizontal deformation is related to the vertical deformation of the component, and creep and shrinkage exert opposite effects on the structural horizontal deformation. Besides, the creep and shrinkage are the dominant factors of the horizontal deformation in the later stage. These results are supported by real deformation data obtained from real‐time deformation monitoring during construction, which proves the effectiveness of the method adopted in this paper. [ABSTRACT FROM AUTHOR]

For testing a conductive pipeline, remote field eddy current testing (RFECT) is used, which is composed of solenoidal exciter coil and receiving sensor coils. In RFECT, there is remote field zone where the eddy current distributions are concentrated on the external surface of the pipe wall. Therefore, it is possible to detect a defect that occurs on the external surface of the pipe wall even if the receiving coils are located inside the pipe. From the measured coil signals, it is necessary to decompose background offset and predict the pattern of defect signal in order to estimate the defect size for the maintenance of underground pipelines eventually. In the process, the amplitude variations of the induced magnetic field at sensor coils are closely related to defect depth. Therefore, it is important to analyze and eliminate distortions of measured RFECT signals. This paper analyzes the effects of the induced magnetic field on the sensing signals with respect to different depth sizes in the RFECT system. The amplitude and the distribution pattern of defect signals are computed by a 3-D finite-element method and the method to eliminate the signal distortions caused by induced magnetic fields are presented. Simulated results in this paper agreed well with measuring ones. [ABSTRACT FROM AUTHOR]

The expansion process of the base pipe of the expanded screen pipe includes large displacement elastic-plastic deformation problems such as geometric nonlinearity, material nonlinearity and contact nonlinearity. In this paper, based on the elastic-plastic deformation mechanism of the base pipe of expanded screen pipe, finite element equations are established and numerical simulation is used to construct a finite element simulation model to study the mechanical behavior and deformation law of F203.2 mm base pipe of the expanded screen pipe expansion process. The results show that the expansion rate has no effect on the increase of wall thickness, and the decrease is proportional to the expansion rate. The greater the expansion rate, the greater the residual stress at both ends of the slot. [ABSTRACT FROM AUTHOR]

In this paper, a novel method for the preparation of ultra-fine-grained bulk materials called asymmetric gradient extrusion (AGE) is proposed. In AGE, the cross-section of the extrusion channel is a rectangle, and two inclined planes are staggered along the extrusion direction. To realize repetitive extrusion, the thickness of the workpiece is limited to be equal to the width of the channel outlet. In order to study the mechanism of ultra-fine grain formation in AGE, the deformation characteristics of AGE were investigated. First, the slip line field method was used to theoretically analyze the deformation characteristics and grain splitting in AGE. Then, the plastic deformation behavior of bulk samples in AGE and traditional extrusion was investigated and compared with the finite element method. In addition, the deformation characteristic and microstructure variation of pure copper bulk samples in AGE were experimentally investigated. The results showed that the deformation characteristics of workpieces were highly related to the two inclined planes within the die channel. Two independent deformation zones can be formed with increasing distance between the two inclined planes. The shear effects in each deformation zone lead to grain splitting during extrusion. Compared with traditional extrusion, the advantage of AGE is its amazing ability to form high and uniform strain during extrusion, which leads to the formation of small and uniform grains in the workpiece. After six passes of AGE, an average grain size of 0.6 μm can be achieved. The enhancement and accumulation of dislocations within grains was the dominating mechanism of grain fragmentation. AGE shows impressive potential in the preparation of ultra-fine-grained bulk materials. [ABSTRACT FROM AUTHOR]

The analysis of the influence of hull deformation on shaft alignment is predominately conducted using the finite element method (FEM), which is time-consuming, labor-intensive, and challenging to use for iterative hull design optimization. In this paper, hull deformation is separated into two parts—global deformation and local deformation, simplified to a single-span beam model and a grillage beam model, respectively—then solved using the matrix displacement method (MDM). Compared to FEM, the proposed method has a small calculation error, proving its correctness, while the calculation time is greatly reduced. The proposed method has been used to calculate the hull deformation of a ship under various conditions and evaluate its influence on shaft alignment. The results indicate that under certain conditions, the bearing reaction forces are constant, whereas the bearing pressure changes as a consequence of the change in shaft-to-bearing angle. The comparison between local rotation and shaft-to-bearing angle reveals that bearings in various positions follow distinct laws. We suggest that the shaft-to-bearing angle be used as an additional parameter in the evaluation of shaft alignment calculations. Moreover, when optimizing bearing pressure, bearings in different positions are affected differently by global and local deformation, and their optimization priorities are distinct. [ABSTRACT FROM AUTHOR]

New energy is the focus of attention all over the world, and research into new energy can inject new vitality into the industrial system. Hydrogen fuel cells are not only environmentally friendly, but also rich in reserves that can be used as a strategic resource for the entire country. The difficulty lies in the safe design of application equipment and the batch generation and storage of hydrogen. In addition, fuel cells have the disadvantage of a slow start-up. Based on the above problems, this paper proposes a hybrid-element method to solve the thermal-mechanical coupling model of fuel cell plate, which can effectively solve the thermal stress change, temperature field distribution and displacement change of the battery plate when working. Firstly, the hybrid-element algorithm is given for 2D plate deformation. Then, the deformation application of a 3D fuel cell plate is given. The 2D numerical results show that the hybrid finite element method (FEM) is more flexible for realizing the flexible combination of sub-mesh and finite element basis functions, and has a better mesh quality compared to the traditional constant strain triangular element (CST) adaptive FEM and quadrilateral isoparametric element (Q4) adaptive FEM. This method achieves a balance between numerical accuracy and solving efficiency for the multi-porous elastic plate. In addition, a deformation control formula is given which can display the displacement deformation and stress merge to same graph, since it is convenient to quickly compare the regions where the displacement and stress extremum appear. In short, the hybrid finite element method proposed in this paper has good mesh evaluation results, and when the number of discrete elements is equivalent, the hybrid element converges faster and the solution efficiency is higher. This paper also provides a good numerical theory and simulation reference for industrial mechanics and new energy applications. [ABSTRACT FROM AUTHOR]

CNC Gantry Type Machine Tools with great distance between slides (gantry milling machines, plasma and laser gantry cutting machines, vertical lathe machines, etc) are used extensively in the manufacturing of large and long components. Because this type of Machine Tool it is used to machine large parts at high speeds, significant heat will be produce at the cutting tool level and transmitted thru the tool holder to the ram or spindled and then to the ream case guideways. Heat it's also generated when using a ball screw actuation for the main axis because of the friction forces at the ball screw level. Due to material expansion, the heat generated during the machining process can influence the precision of the Machine Tool. In this paper, finite element analysis (FEA) was used to analyze the influence of the temperature on the rigidity of the Machine Tool guideways. The results of the studies performed will provide the machine tool builder with important information regarding the points that need to be address in order to help in improving thermal compensation. [ABSTRACT FROM AUTHOR]

Aiming at the problems of a large amount of material cutting waste or large forming load when large gear profile forming adopts overall cutting or precision forging process, this paper proposed a three-roller bending process (TRBP) for large gear teeth profile, and analyzed the deformation mechanism of the rack bending, meanwhile the gear chain for roll forming was designed. Finite element analysis (FEA) was carried out to numerically simulate the load effects of both the precision forging process and the TRBP for the large gear teeth profile in 17CrNiMo6. The effects of deformation force and strain of TRBP for large gear teeth profile were analyzed. The results showed that as the deformation temperature and speed increase, the deformation force and strain required by the gear profile gradually change. And the reasonable parameter of TRBP is around 750 ∘ C of deformation temperature and 0.5 mm · s - 1 of speed. Compared with the precision forging process under the same boundary conditions, the deformation force of the gear profile TRBP has decreased by about 99 % which could significantly reduce the tonnage requirement of deforming equipment. [ABSTRACT FROM AUTHOR]

Purpose The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper aims to analyze the influence mechanism of flexible parts deformation on the geometric precision, and then to ensure the reliability and stability of the mechanical system.Design/methodology/approach Firstly, this paper adopts the N-GPS to analyze the influence mechanism of flexible parts deformation on the geometric precision and constructs a coupling 3D tolerance mathematical model of the geometric tolerance and the load deformation deviation based on the SDT theory, homogeneous coordinate transformation theory and surface authentication idea. Secondly, the least square method is used to fit the deformation surface of the mating surface under load so as to complete the conversion from the non-ideal element to the ideal element.Findings This paper takes the horizontal machining center as a case to obtain the deformation information of the mating surface under the self-weight load. The results show that the deformation deviation of the parts has the trend of transmission and accumulation under the load. The terminal deformation cumulative amount of the system is up to –0.0249 mm, which indicated that the influence of parts deformation on the mechanical system precision cannot be ignored.Originality/value This paper establishes a comprehensive 3D tolerance mathematical model, which comprehensively considers the effect of the dimensional tolerance, geometric tolerance and load deformation deviation. By this way, the assembly precision of mechanical system can be accurately predicted. [ABSTRACT FROM AUTHOR]

In order not to get bridges collapsed instantaneously, this paper introduces the degradation laws of mechanical performance of corroded steel by making use of different electrochemical detections (by electrochemical detection, the features of corroded steel could be obtained quickly) and finite element analysis. Then according to the laws, this paper sets up “time-varying model” for the situation that carrying capacity changes because part of the bridge suffers corrosion. By the “time-varying model”, a scientific deduction on the remained service life can be made. In this way, a relatively accurate forecast on the durability of bridges being used can be achieved. First, by a orthogonal test where the simulated corrosion is sped up, a relationship between electrochemical signal and corrosion ratio was established; second, by finite element analysis, a relation model between the steel corrosion and steel deformation obtained by electrochemical detection. By linking “potential signals -corrosion degree - deformation degree” and detecting the crystal microstructure of corrosion section, macroscopic deformation and microstructure of the materials were correlated. Then, under a complicated stress, this paper introduces the emergency response system and evolution mechanism of the corroded steel. By setting up a time-varying model involving “electrochemical signals - corrosion degree- deformation degree”, a fast diagnosis system based on electrochemical signal is formed. Depending on such a diagnosis system, a forecast system to predict the durability of the bridges being used can be made, which is similar to the medical judgment that someone's lifetime or age can be predicted by the bone age. Then pursuant to the forecast, we can prevent crises before they emerge. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the unique low rigidity of thin-walled parts, significant machining deformation may occur in the milling process. A deformation prediction model is presented in this paper while considering the effect of the removed material on the global stiffness matrix. Aiming at reducing the scale of the global stiffness matrix, the super-element method is firstly used and the scale of the stiffness matrix is significantly reduced about 30%. And then, the stiffness matrix of the in-process workpiece (IPW) is directly obtained by eliminating the contribution of the removed nodes in the global stiffness matrix. This method can avoid re-building the geometric model or re-meshing the finite element (FE) model in the machining process. To improve the inverse calculation efficiency of the stiffness matrix, a novel nodes re-sorting method is proposed based on the calculation order of the matrix blocks in LU decomposition and inverse calculation. Furthermore, the optimal stiffness direction is discussed and applying the cutting force in this direction can minimize the machining deformation. The simulation results verified the existence of the optimal stiffness direction. Finally, the simulation and experiment are carried out to validate the accuracy of the proposed model. [ABSTRACT FROM AUTHOR]

Due to the fast growth of urban areas worldwide, the demand for tunnels in developed areas is increasing. The design and construction of those tunnels are complex because of their shallow depths and their interaction with existing aboveground and buried structures, which results in rather limited allowable ground deformations induced by the tunnel excavation and support. In tropical regions, residual porous soils near the surface are common. Those soils are highly deformable; thus, tunneling may induce large ground deformations that may damage nearby structures. The new Austrian tunneling method (NATM) and the sprayed concrete lining (SCL) technique are being widely employed in several big cities in tropical regions, but little research has been conducted to assess the induced ground deformations in residual soils, common in tropical areas. This paper provides insight into this issue. A well-documented metro tunnel in São Paulo, Brazil, in a residual red porous clay, was analyzed using 3D finite element method (FEM). The behavior of the residual red porous clay was approximated by an advanced constitutive soil model calibrated with triaxial tests on intact samples extracted at the site. Predictions of the tunnel deformations during construction matched the field data. The calibrated model was then used to explore the tunnel performance under different construction strategies. The influence of partial face excavation, unsupported span length, support stiffness and pipe roof umbrella were assessed. The numerical results showed that partial face excavation was effective to reduce ground deformations ahead of the face of the tunnel and to improve face stability; however, the settlements behind the face increased because of the delay in closing the primary lining. The installation of a stiffer liner closer to the face reduced the ground deformations significantly. The pipe roof umbrella was the most effective technique to reduce the ground deformations around the tunnel; however, the numerical results did not consider deformations that could be induced by the drilling and grouting operations. The results shown in this paper provide both qualitative and quantitative information about the ground deformations induced by NATM tunneling in residual porous soils, that could help designers and contractors choose the optimum support and construction methods to minimize ground deformations. [ABSTRACT FROM AUTHOR]

This paper describes an efficient method of manufacturing thin-walled metal tubes. The proposed method is an expansion drawing and it consists of two stages, flaring and drawing, during which high thickness reduction is achieved because the tube being processed is subjected to tensile stress in both the circumferential and axial directions. The optimal plug half-angle for various materials is investigated using a finite element analysis and experiments, revealing the plug shape with the highest expansion limit and the highest thickness reduction ratio. To investigate the deformation characteristics of different materials during the expansion drawing process, the strain in tubes formed using different materials was measured experimentally using a square grid on the outer surface of the tubes. In addition, a finite element analysis using hypothetical material properties revealed that the work-hardening exponent and friction coefficient affect tube deformation. The results of this work explain the influences of material properties on experimentally observed phenomena. Materials with a large work-hardening exponent are less prone to thinning during forming and have a greater forming limit. On the other hand, the larger the friction coefficient between the plug and the mother tube, the larger the deformation in the axial direction was, and then the thickness reduction increased due to biaxial tension. [ABSTRACT FROM AUTHOR]

Mechanical metamaterials are valued for their diverse properties and potential applications. Due to the instability and large deformability of soft mechanical metamaterials (SMMs), geometric reorganization will occur and lead to some unusual properties. It is possible to change the properties of materials by varying the parameters. Conventional SMMs contain a periodic distribution of holes with the same size and shape, which can be changed to a lesser extent. Periodic dispersion of regular through-hole patterns of various sizes or shapes into elastomers, resulting in metamaterials with more mechanical functionality and deformation scenarios. In this paper, we investigated the influence of parameters on the buckling mechanical behavior of SMMs and the buckling mechanical behavior of structures with multiple sizes and geometric shapes. The parameters studied include geometric parameters (pore shape, porosity and area ratio) and physical parameters (Poisson's ratio and compression mode). Simulation of the buckling behavior of SMMs uses the finite element method. The finite element software ABAQUS is used, taking into account the almost incompressible characteristics of materials, the triangular quadratic plane strain hybrid element is selected (CPE6H). Numerical calculation gives the following results: Area ratio, pore shape and compression mode have obvious effects on buckling behavior, but Poisson's ratio has little effect; the influence of parameters on the buckling critical strains varied for SMMs with various pore shapes; very different buckling behaviors will result from swapping out the pattern of holes with the same size or shape for holes with two different sizes or shapes; the expression of buckling behavior is also varied when the mix of hole shapes is modified. These findings demonstrate that the design parameters may be used to achieve the desired buckling behaviors. This is a new method that can be used to control the deformation of structures; modify the properties of the SMMs without changing stiffness; simplify the structures without significantly changing the material properties. The design path of mechanical metamaterials is increased. [ABSTRACT FROM AUTHOR]

Triply periodic minimal surfaces (TPMS) and honeycomb structures are typical representatives of porous structures. In this paper, multi‐layer structures based on the combination of P‐surfaces and honeycomb structures are fabricated and the compression deformation characteristics are investigated based on quasi‐static compression tests and finite element simulation. The results show that the established finite element model can better simulate the deformation and damage modes of the multi‐layer structure, and the multi‐layer structure exhibits layer‐by‐layer deformation and sequential compression collapse in the deformation process. The tensile stress is crucial in the deformation and damage process of the P‐structure layer. The honeycomb structure layers show two different deformation modes: the inverted bell‐shaped "upward extrusion" and the bell‐shaped "downward extrusion." [ABSTRACT FROM AUTHOR]

This paper addresses the problems of easy deformation, difficult dimensional control and difficult accuracy assurance during the production of thin-walled gears for helicopter spoke cutting. It uses finite element simulation technology, metal cutting principles, process optimization and other design and manufacturing technologies to reveal the causes of cutting deformation, effectively predict the deformation of parts during cutting, and develop reasonable deformation control strategies. This study explores the effects of cutting force, residual stress and clamping method on gear machining deformation. The deformation of the spoke plate is analysed by finite element simulation. Abaqus software is adopted to establish a finite element model for 2D turning simulation to predict the machining residual stresses and cutting forces during gear turning machining with different cutting parameters. The simulated cutting forces are compared with the residual stresses and experimentally measured values to verify the accuracy of the finite element model and provide a theoretical basis for model construction in the next simulation study. With Abaqus software, the effect of different cutting forces on the deformation of the spoke plate is simulated, and the effect of the superposition of cutting and clamping forces on the deformation of the spoke plate is simulated using life and death cell technology to simulate the machining of the workpiece. Then, a corresponding fixture is designed to realise the corresponding clamping position for machining experiments, and the deformation of the spoke plate is measured by CMM (coordinate measuring machine) to verify the realism of the simulation. This research provides scientific theoretical guidance and process support for aerospace thin-walled gear spoke plate turning. [ABSTRACT FROM AUTHOR]

The existing inherent strain method is improved in this paper to address the shortcomings of the existing inherent strain method in the process of loading inherent strain. Unlike the traditional inherent strain method, which uses one-step loading inherent strain for each weld seam for one-time elastic calculation, the improved inherent strain method uses step-by-step loading inherent strain for each weld seam for multiple elastic calculations to predict welding deformation. The step-by-step loading inherent strain method (SBS-ISM) is more in line with the actual welding deformation generation process. Firstly, the local finite element model of the T-joint was used to analyze the welding deformation and extract the inherent strain by using the thermal elastic–plastic finite element method (TEP-FEM). Subsequently, the one-step loading inherent strain method (OS-ISM) and the step-by-step loading inherent strain method (SBS-ISM) were used to predict the welding deformation for the same local finite element model, respectively. The comparative results showed that the trend and magnitude of welding deformation calculated using SBS-ISM was much closer to those calculated using TEP-FEM. The OS-ISM and SBS-ISM were used to predict the welding deformation of the backward centrifugal fan impeller under different welding sequences, respectively. By comparing the welding deformation results calculated using the two inherent strain methods with the experimental results, it was demonstrated that the step-by-step loading inherent strain method (SBS-ISM) provides more accurate and reliable predictions of welding deformation for large and complex thin-walled T-shaped structural components compared to the one-step loading inherent strain method (OS-ISM). [ABSTRACT FROM AUTHOR]

In this paper, we aim to explore the mechanical potentialities of a material made of an orthogonal net of fibers arranged in logarithmic spirals. Therefore, an annular plate described with a second-gradient model is envisaged to evaluate the behavior of such material in a nonlinear elastic regime when large displacements and deformations occur. Several mechanical tests are performed numerically under the finite element method approximation obtained directly with a weak formulation based on the elastic energy that it is assumed to be predictive for this kind of network system of fibers. Plots reporting the mechanical characteristics in all the considered tests are provided to illustrate the overall mechanical behavior of the evaluated system. [ABSTRACT FROM AUTHOR]

The bridge's span structure comprises a connected beam designed to support a concrete slab poured over parallel steel supports. Simultaneously, segmental construction, shrinkage, and the flow of concrete play a significant role in stress redistribution over time. The span construction is statically indeterminate due to its connections with the abutments, and temporal deformations occur under additional complex conditions. In this analysis, we employed a calculation model based on the layered finite elements method developed by the authors. This model can be utilized to analyse both statically indeterminate supports and the predicted phased construction method. It accounts for changes in the static system and loading, as well as variations in the layers within the coupled section and the viscous properties of the concrete over time. The calculation analysis results reveal that viscous concrete deformations, combined with different moments of activation of individual segments, have a significant impact on stress redistribution over time. Such intricate analyses are indispensable for ensuring the required safety and cost-effectiveness of the bridge span construction. [ABSTRACT FROM AUTHOR]

At high speeds and under large axial forces, the disc–drum combined structure exhibits inconsistent deformation between parts. The difference in the structural characteristics of different parts, the speed, the preload, and its distribution mode, along with other factors, make the deformation of parts more complex, resulting in the deformation of parts during work; this deformation inconsistency has a direct impact on the engine performance. This paper presents a systemic investigation of the uncoordinated bolt deformation of an aeroengine. The finite element model of the disc–drum combined structure is established using Ansys workbench, where the deformation is uncoordinated. On this basis, the influence of different preload forces and various rotation speeds on the deformation discordance of the combined structure are discussed. Then, the relationship between the bolt deformation and component deformation incompatibility is obtained through a comprehensive analysis of the bolt deformation. A set of detailed analyses was carried out to investigate the uncoordinated deformation caused by the uneven distribution of the preload force. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing availability of affordable finite elementmodeling software and computational fluid dynamics codes have given today's sailing yacht designers tools that, in the past, were only available to designers of yachts competing in the most high-profile events. This paper provides a case study on the structural design of the International America's Cup Class Yacht Stars & Stripes USA-34, which won the U.S. defender series, the Citizen Cup, leading up to the 29th America's Cup competition in 1995. The authors have recently been able to publicly share this information, and feel that the problem-solving approach is of direct use to many of today's designers. The design approach is twofold, the first being the use of Finite Element Analysis to minimize draginducing local deformations. Over 80 finite element models were analyzed with varying configurations, starting with an initial baseline structure based on the previous boat, USA-11. These structural improvements reduced local hull deflection from5 to 6 mmper meter on the previous design to less than 1 mm per meter on the USA-34 design. The second part of the design approach isolates the hydrodynamic effects of global bending under rig tension. Illustrative tank tests are provided to demonstrate how the global sagging of the hull, caused by rig tension, can often increase the resistance of a yacht (especially one built for racing). As part of a series of steps taken to mitigate the effect of rig tension, a novel design was developed, with soft patches and flexible structure to permit low-costmodification of the hull in the boatyard, giving approximately a 225mmincrease in waterline length and 75 mm reduction in beam if needed--a modification that was made to USA-34 prior to winning the finals of the Citizen Cup, and at a cost of under $500. The reduction of drag-inducing local hull form deformations, and the development of the cost-saving hull modification concept, demonstrate how a creative designer can take advantage of the finite elementmodeling tools that are now widely available. [ABSTRACT FROM AUTHOR]