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The curing distortion is a critical determinant of the quality of integrally manufactured composite structures, playing a pivotal role in the design and fabrication of composite. This paper presents two simplified methods in predicting the curing distortion for large-scale composite aircraft structures manufactured through the autoclave process. Firstly, the refined finite element models of the two simplified methods were developed. Then, it was utilized to predict the curing distortion of Ω-shaped composite laminates. The comparative study between the experimental data and numerical results shows that the proposed second simplified method balanced the prediction accuracy and efficiency, which is urgently needed in practice. Finally, using the second simplified method, predictions were conducted for the curing distortion of practical large-scale composite skin structures. The results were in good agreement with the corresponding experiments. This study provides a new solution for the rapid iterative design of large-scale composite structures, as well as the efficient design of frame molds for their manufacturing. [ABSTRACT FROM AUTHOR]

Conventional beam elements ignoring distortion may overestimate the lateral resistance of frames and curved beams made of monosymmetric I-sections. This paper introduces two new distortional modes represented by mechanical couples relative to twisting and shearing of the two flanges that are opposite in directions but unequal in magnitudes. A straight beam element with nine degrees of freedom (DOFs) per node, including the conventional three translations, three rotations, warping and the new two distortions, is newly derived. This allows all the DOFs of the connected elements at a common joint to be easily transformed to the global coordinates for stiffness assembly. As a result, the warping–distortion compatibility problem that occurs in frames and curved beams is resolved. In the numerical examples, the results produced by the present beam element is demonstrated to agree excellently with the shell-element solutions for the lateral-distortional deformation of the angled frame and curved beam. It is observed that the cross-sectional distortion effect becomes extremely significant for angled frames of short unbraced length and for curved beams of high curvature. [ABSTRACT FROM AUTHOR]

In this paper, the accurate free vibration characteristics of thin-walled box beam are discussed and the kinematic model is established by using fine shear deformation theory. The model adopts the in-plane and out-of-plane displacement fields including extension, torsion, warping and distortion, as well as the transverse shear due to bending and warping due to torsion. One-dimensional high-order beam theory is applied to the dynamic solution of thin-walled box beam, and the analytical solution of high free vibration modes of multi-deformation coupled modes under different boundary conditions is derived. The results show that warping, distortion and shear deformation play an important role in the free vibration characteristics of thin-walled box beam, and the validity of the model is verified. In addition, finite element software (ANSYS) is used for finite element simulation. The application of vibration mode in the structure design of thin-walled box beam is summarized, especially in the case of higher natural frequency. The calculation method is in good agreement with the finite element results. [ABSTRACT FROM AUTHOR]

This study presents a warping included mixed finite element formulation for the static and stress analyses of functionally graded (FG) exact curved beams. Another distinctive feature of this study is to present the range of geometric and material parameters where the first-order shear deformation theory lacks necessary precision. The constitutive equations are derived from the 3D elasticity theory of an elastic continuum. The couple effects are considered in addition to the variations of FG material constituents through the transverse/axial directions. The mixed finite element formulation is enhanced by the cross-sectional warping deformations over a displacement-type finite element formulation. The two-noded curved mixed finite elements with 12 degrees of freedom at per node are derived over exact curvature and length. Satisfactory results are obtained for the static responses and stresses of axially FG-sandwich and transversely FG exact curved beams with power-law dependence compared to the 3D behavior of brick finite elements. Finally, the influences of ellipticity, width to thickness ratio, FG material constituents, and material gradient index on the static response of FG exact curved beams are investigated. [ABSTRACT FROM AUTHOR]

This study is based on a theory for analyzing non-uniform torsion in thin-walled beams made of homogeneous elastic material with arbitrary cross-sections by incorporating the effect of the shear deformation of a cross-section. Utilizing the Finite Element Method (FEM), the proposed numerical approach addresses non-uniform torsion by breaking down a 3D analysis into 2D cross-sectional and 1D modeling components. Initially, the geometric constants of the cross-section were computed using a 9-node isoparametric element in 2D FEM. Subsequently, a 1D FEM employing a linear isoparametric element calculated the twist angle, torsion warping parameters, and stress results. The stress field was determined through a local analysis of the 2D cross-section. Notably, the 2D FEM component aligns with contemporary trends in commercial software, thereby bolstering the potential and practical applicability of the proposed numerical approach. Its verification and validation through numerical analyses using MATLAB underscore the efficacy and reliability of the method in analyzing non-uniform torsion behavior in structural design, particularly under diverse boundary conditions. [ABSTRACT FROM AUTHOR]

Together with axial and flexural actions, modern-designed reinforced-concrete walls can also be subjected to torsion during rare loading events, such as large-magnitude earthquakes or strong winds. For certain widely used nonplanar open cross-section geometries, this torque is resisted primarily through warping. In some cases, the longitudinal stresses caused by torsional warping can be of the same order of magnitude as those caused by flexure, which postulates a reduction of the in-plane bending moment capacity of the section. This study explores the reduction of bending moment capacity of open reinforced-concrete U-shaped core walls due to the simultaneous application of flexural, axial, and torsional loading. Initial investigations focused on strain gradients through the wall segments of reinforced-concrete U-shaped walls. Using a refined data set from a recent experimental campaign, the commonly assumed linear strain gradient used in the design of reinforced-concrete walls is challenged. Numerical methods that intrinsically rely on the observed strain gradients are then employed to compute, for a range of torque-to-bending-moment ratios, the ultimate bending moment and torque capacities from combined loading scenarios. The numerical results corroborate existing experimental results, indicating a significant reduction (almost half) in ultimate bending moment capacity when a torque equal to approximately 20% of imposed bending is applied. Interaction diagrams between the ultimate torque and bending moment show that it is possible to derive a simple relationship between the two for the purposes of structural design. These results can help formulate guidelines for future international building codes, which in their current form cannot account for the design of open sections governed by warping torsion. [ABSTRACT FROM AUTHOR]

AbstractThe current research presents a dynamically coupled mathematical model considering the energy method and employing the classical Ritz-approximation method for a thin-walled anisotropic tapered rotating box beam. The novelty of this work lies in presenting the effect of circumferentially uniform stiffness (CUS) ply layup to investigate the reverberations of not considering bending-shear couplings toward vibration behavior. The current model is formulated by considering transverse shear and cross-sectional warping of order primary and secondary. The repercussions of not including non-classical effects like Coriolis-force, centrifugal-acceleration and warping, inertial-warping is explored. Mode switching arising for change in geometry and centrifugal stiffening is presented for various ply angles and rotational speeds. [ABSTRACT FROM AUTHOR]

A variationally consistent analytical beam model that describes the theory in a Timoshenko-Vlasov level is developed based on Reissner's mixed variational theorem. Starting from a shell theory, all the field-governing equations (equilibrium and continuity) and the boundary conditions of the shell wall are derived in closed form, and the mixed method enables finding the explicit forms of the reactive stresses and sectional warpings which are evaluated progressively depending on the level of beam model to be analyzed. The stress recovery part is incorporated in the post-stage of the analysis to compute the layer-wise distribution of stresses over the beam cross-section. The present analysis is validated against numerous benchmark examples available in the literature, including beams with multi-layered strip section, thin-walled anisotropic box sections with elastic couplings, and two-cell airfoil section. The comparison study demonstrates excellent correlations with the results from detailed three-dimensional finite element analysis and other up-to-date beam approaches. Also presented are symbolically expressed stiffness coefficients and the sectional warping modes of coupled composite beams to demonstrate the strength of the proposed beam model. [ABSTRACT FROM AUTHOR]

The clonal materials of Tectona grandis L. f. in fast-growing plantations exhibit faster growth than the seminal materials. Therefore, it is necessary to investigate the differences in wood drying to ensure the quality and yield of the final product. This study evaluated the outdoor drying behavior of three genotypes of teak lumber. Two clonal genotypes (G1 and G2) and one of seminal origin (G3) were assessed. Boards measuring 30 × 150 × 1000 mm (thickness × width × length) were produced from the basal logs. The average moisture content (79.3, 64.9, and 60,1%), final moisture content (10.8, 9.8, and 11.6%), and mean drying rate (1.2, 0.97, and 0.85%.day-1) were observed in the wood from genotypes G1, G2 and G3, respectively. The clonal material crooked and bowed below 5 mm.m-1, which is considered the tolerance limit for both warpings. The seminal material had a greater incidence of splitting. The clonal genotypes G1 and G2 had similar qualities and presented higher drying rates, final moisture contents below 11% and a lower incidence of defects, especially splitting, compared to the naturally seeded material. [ABSTRACT FROM AUTHOR]

A problem of restrained torsion of thin-walled beams under the action of an end torque is considered. The asymptotic splitting method is applied to obtain a system of resolving equations that describes combined torsion, tension-compression, and bending of the beam. The example of typical cross sections is used to compare the resulting model with a stress-strain state in the beam, determined in the calculation using the developed model and three-dimensional numerical calculation by the finite element method. The resulting mathematical model is analyzed and its advantages are revealed and compared to the widely used Vlasov theory. It is shown that the developed model does not contain the restrictions imposed by the Vlasov theory hypotheses, such as the nondeformability of the cross-sectional contour and the absence of shear strains on the middle surface. The resulting model makes it possible in many cases to more accurately determine the emerging stress-strain state. In particular, it is shown that the developed model accounts for the presence of a boundary layer near the clamped end, which arises during torsion of angle sections and makes a significant contribution to longitudinal stresses, while the Vlasov theory does not allow for the recovery of the arising longitudinal stresses. [ABSTRACT FROM AUTHOR]

Fused filament fabrication, also known as material extrusion, is an additive manufacturing process used in many industries. Despite its widespread application, common issues like an unwanted deformation of the part to be printed during the process are rarely investigated. These failures, called warping, can be avoided by a sufficient adhesion between build surface and part. Although printing processes can last up to several days, the time dependencies and the mechanism causing adhesion are poorly understood. For this reason, the time dependence of adhesion between polylactic acid and polyamide as printing materials and different building surfaces will be investigated. The adhesion forces can change up to 60% within 20 minutes dependent on the build surface temperature. Higher build surface temperatures lead to a stronger change. These results indicate that besides mechanical adhesion other mechanisms could be involved. Adhesion measurements before and after sandblasting the build surfaces support this. For brass and borosilicate glass as build surface materials, a complete loss of adhesion was observed, whereas it did not change for Pertinax. These overall results lead to the assumption that adhesion occurs because of ionic bond onto brass surfaces and because of hydrogen bond onto borosilicate glass and Pertinax. [ABSTRACT FROM AUTHOR]

The displacement field and governing equation completely depend on the cross-section shape in the torsion of nano-bars. Due to the torsion of structure and warping of its cross-section, axial strain is created. A review of the literature demonstrates that the effect of the normal strain in the torsional analysis of nanostructures with non-circular cross-sections is ignored for the sake of simplicity and causes a computational error. While in the torsion of short nano-bars due to the great warping of the cross-section the normal strain appears and it shouldn't be ignored. Therefore, for the first time, the effect of normal strain based on the torsion of Timoshenko-Gere theory is considered in this research. In this theory, the twist rate of non-circular sections in the axial direction is not considered constant, unlike studies in the literature. The governing equation of torsional vibration is extracted using the Hamilton principle, and the nonlocal strain gradient theory is used to show the size-dependent effects. The fundamental frequency is calculated for the arbitrary cross-section shape by using Galerkin's method. The effect of parameters such as size effects, the thickness of nano-bar, mode number, and dimensions changes of cross-section versus natural frequency of nano-bar for both the Timoshenko-Gere and typical theories are investigated. Results indicate that neglecting normal strain due to warping the cross-section causes a significant error in the short nano-bars, especially at higher mode numbers. Also, a comparison is made between the obtained natural frequencies and those of the results reported in the literature. [ABSTRACT FROM AUTHOR]

When designing steel members with nonsymmetric cross sections, it is essential to consider twisting effects when performing stability checks via second-order analysis according to the ANSI/AISC 360-22. Existing line-element formulations for nonsymmetric sections are mostly derived based on thin-walled assumptions, leading to an overestimation of member strength due to the inaccurate prediction of member behavior, especially when the cross sections have moderate wall thickness. This paper proposes an efficient line-element method for second-order analysis of steel members with nonsymmetric thick-walled sections considering the warping degree of freedom (DOF) and the twisting effects along with the transverse shear deformations. Additionally, a two-dimensional (2D) finite-element cross section analysis method employing the constant strain triangle (CST) element is developed to calculate the section properties for arbitrary cross sections, including the Wagner and the shear coefficients. The proposed method is implemented in the educational structural analysis software MASTAN2 and verified through two sets of examples. [ABSTRACT FROM AUTHOR]

To be able to produce ceramic bodies with complex shapes without interlayer delamination and warping through vat photopolymerization‐based 3D printing techniques, photosensitive ceramic slurries should be studied to prepare 3D printed green and sintered bodies. In this study, we developed dual curable acrylate–epoxide ceramic slurries for digital light processing (DLP) 3D ceramic printing. The dual curing process of the slurries is a combination of photo‐radical polymerization of acrylate and thermal cationic polymerization of cyclo‐aliphatic epoxide. The green bodies prepared by dual curing of the slurries showed higher fracture strength and better adhesion between layers and between starting particles and binder polymer in comparison to acrylate‐based green body. These advantages were due to higher crosslinking density of the binder matrix and hydrogen bonding by hydroxyl groups from epoxide ring opening. The green and sintered bodies printed with improved slurry and DLP 3D printer had flat shape without warping unlike those from acrylate‐based bodies. Moreover, the distribution of inter‐particle necking in the sintered body was uniform and the interface boundary between layers was not observed. This is because of excellent uniformity of the dual cured acrylate–epoxide polymer matrix (uniform crosslinking density in layers) in the green body and hydroxyl groups generated by epoxy ring opening. [ABSTRACT FROM AUTHOR]

The warping may become an important factor for the precise transverse vibrations of curved beams. Thus, the first aim of this study is to specify the structural design parameters where the influence of cross-sectional warping becomes great and the first-order shear deformation theory lacks the precision necessary. The out-of-plane vibrations of the first-order shear deformation theory are compared with the warping-included vibrations as the curvature and/or thickness increase for symmetric and asymmetric transversely-functionally graded (TFG) curved beams. The second aim is to determine the influence of design parameters on the vibrations. The circular/exact elliptical beams are formed via curved mixed finite elements (MFEs) based on the exact curvature and length. The stress-free conditions are satisfied on three-dimensional (3D) constitutive equations. The variation of functionally graded (FG) material constituents is considered based on the power-law dependence. The cross-sectional warping deformations are defined over a displacement-type FE formulation. The warping-included MFEs (W-MFEs) provide satisfactory 3D structural characteristics with smaller degrees of freedom (DOFs) compared with the brick FEs. The Newmark method is used for the forced vibrations. [ABSTRACT FROM AUTHOR]

In this paper, we show that any displacement of a plate is the sum of a Kirchhoff–Love displacement and two terms, one for shear and one for warping. The plate is then loaded so that bending and shear contribute the same order of magnitude to fiber rotation. [ABSTRACT FROM AUTHOR]

The present work focused on the effect of deposition path on the transient temperature distribution, heat transfer, residual deformation and residual stress of a rectangular solid deposited by electron beam freeform fabrication technology. To achieve this aim, three representative deposition paths were involved to produce rectangular solid by electron beam freeform fabrication technology. Thermal‐mechanical decoupling simulations were carried out with respect to three different deposition paths. Both of the experimental and simulation results showed that a shorter deposition track can remarkably reduce the residual stress and warping. After separating the deposition area into small segments, remarkable local bulges were formed near the conjunction lines, and overheating was prone to occur at the turning points of the conjunction lines. The present work is helpful to the selection of deposition path for additive manufacturing process. [ABSTRACT FROM AUTHOR]

We provide statistical analysis methods for samples of curves in two or more dimensions, where the image, but not the parameterization of the curves, is of interest and suitable alignment/registration is thus necessary. Examples are handwritten letters, movement paths, or object outlines. We focus in particular on the computation of (smooth) means and distances, allowing, for example, classification or clustering. Existing parameterization invariant analysis methods based on the elastic distance of the curves modulo parameterization, using the square‐root‐velocity framework, have limitations in common realistic settings where curves are irregularly and potentially sparsely observed. We propose using spline curves to model smooth or polygonal (Fréchet) means of open or closed curves with respect to the elastic distance and show identifiability of the spline model modulo parameterization. We further provide methods and algorithms to approximate the elastic distance for irregularly or sparsely observed curves, via interpreting them as polygons. We illustrate the usefulness of our methods on two datasets. The first application classifies irregularly sampled spirals drawn by Parkinson's patients and healthy controls, based on the elastic distance to a mean spiral curve computed using our approach. The second application clusters sparsely sampled GPS tracks based on the elastic distance and computes smooth cluster means to find new paths on the Tempelhof field in Berlin. All methods are implemented in the R‐package "elasdics" and evaluated in simulations. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) includes a few printing techniques widely used, in recent years, concerning the additive manufacturing of Ti6Al4V alloys. These produced parts, typically utilized in sectors such as aerospace and biomedical, are characterized by very high added value. It is therefore fundamental to identify the influence of process parameters typical of LPBF technology on the occurrence of warping leading to process failure. This study deals with the characterization of single-track and "micro-scale" level warping phenomena which may lead to protrusion of material over the powder bed and process failure before normal termination. This phenomenon was investigated as a function of process parameters, referring also to the strength and ductility characteristics of the manufactured samples. With this purpose, several samples were printed using variable process parameters both in terms of line energy density (LED) values and in terms of laser power and speed combinations such as to guarantee constant LED values. For the samples that did not show significant micro-warping phenomena, in addition to the transversal and longitudinal geometric characterization of the single track, tensile tests were performed to determine both the resistance of the material and the ductility characteristics. The single tracks, for given process parameters, were printed on a homogeneous material substrate. For every single track, a microstructural and morphological transverse and longitudinal characterization has been carried out and the measured geometrical features were correlated to the process parameters. The obtained results allowed the identification of a new threshold parameter, indicating the limit operating conditions beyond which significant warping phenomena and process failure occur. [ABSTRACT FROM AUTHOR]

Fused filament fabrication, also called material extrusion, is a widespread used 3D-printing process which allows to manufacture parts with a high freedom of design at low costs. A common issue is the deformation of parts during the printing process caused by thermal stress and an insufficient adhesion. Despite the widespread usage of material extrusion only few publications dealing with this topic and it is yet nearly unknown, which process parameters have an influence onto the part adhesion nor how they interact among each other. This publication investigates how the adhesion between part and build surface is affected by the most important process parameters. The influence of the first layer's height, printing speed, nozzle temperature, and build surface temperature was determined for three different build surface materials. Furthermore, the interactions of these parameters among each other were investigated. It was found that the first layer's height has a strong influence onto the adhesion, which can be increased up to 0.56 MPa. Also, a strong dependence of printing speed, build surface temperature and nozzle temperature among each other was found. [ABSTRACT FROM AUTHOR]

The warping effects may predominate in geometrically nonlinear analysis of open cross-section members. The formulation of conventional beam-column elements incorporating the warping effects is cumbersome due to the method considering the inconsistency between the shear center and centroid. To develop a concise warping element formulation, this paper presents a transformation matrix to integrate the inconsistent effects into the element stiffness matrix. The co-rotational (CR) method used to establish the element equilibrium conditions in the geometrically nonlinear analysis is adopted to simplify the element formulation and improve the efficiency of nonlinear analysis. A new beam-column element explicitly considering the warping deformation and the Wagner effects is derived based on the CR method and the Euler–Bernoulli beam theory. A detailed kinematic description is provided for considering large deflections and rigid body motions. Based on the mechanical characteristic, the coordinate and the rigid body motion transformation matrices are given. The secant relationship is developed to evaluate the element internal forces accurately and effectively in each iteration. Several verification examples are provided to validate the proposed method's reliability and robustness. The verifications demonstrate that the proposed element leads to considerable computational advantages. The results of this paper are useful for future upgrading of frame analysis software with warping degrees-of-freedom (DOFs). [ABSTRACT FROM AUTHOR]

In this paper, a new finite element for 2D non-prismatic (curved and tapered) elastic beams with narrow rectangular cross-section is proposed. The element is geometrically exact, hence capable of handling large displacements and finite rotations, and allows for cross-section arbitrary warping through the inclusion of additional degrees of freedom (DOFs). These additional DOFs make it possible to capture the non-standard shear stress distributions that are developed in tapered members. All expressions required to implement the proposed finite element are derived and written in a simple vector/matrix form. To assess the accuracy and demonstrate the capabilities of the proposed element, several numerical examples are presented. For comparison purposes, results obtained with refined meshes of standard 2D finite elements are also shown. It is concluded that the proposed element leads to very accurate results with a small computational cost. [ABSTRACT FROM AUTHOR]

We present neural network-based constitutive models for hyperelastic geometrically exact beams. The proposed models are physics-augmented, i.e., formulated to fulfill important mechanical conditions by construction, which improves accuracy and generalization. Strains and curvatures of the beam are used as input for feed-forward neural networks that represent the effective hyperelastic beam potential. Forces and moments are received as the gradients of the beam potential, ensuring thermodynamic consistency. Normalization conditions are considered via additional projection terms. Symmetry conditions are implemented by an invariant-based approach for transverse isotropy and a more flexible point symmetry constraint, which is included in transverse isotropy but poses fewer restrictions on the constitutive response. Furthermore, a data augmentation approach is proposed to improve the scaling behavior of the models for varying cross-section radii. Additionally, we introduce a parameterization with a scalar parameter to represent ring-shaped cross-sections with different ratios between the inner and outer radii. Formulating the beam potential as a neural network provides a highly flexible model. This enables efficient constitutive surrogate modeling for geometrically exact beams with nonlinear material behavior and cross-sectional deformation, which otherwise would require computationally much more expensive methods. The models are calibrated and tested with data generated for beams with circular and ring-shaped hyperelastic deformable cross-sections at varying inner and outer radii, showing excellent accuracy and generalization. The applicability of the proposed point symmetric model is further demonstrated by applying it in beam simulations. In all studied cases, the proposed model shows excellent performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Steel thin-walled profiles are the backbone of modern lightweight construction, offering exceptional efficiency in terms of material use and assembly speed. However, their inherent susceptibility to buckling under complex loading conditions, especially bending torsion, has limited their broader application in advanced structural systems. This paper introduces a groundbreaking method for analyzing the bending-torsion behavior of steel thin-walled C-profile beams, specifically focusing on the critical but often overlooked factor of support warping stiffness. Unlike conventional studies that primarily examine local or global buckling resistance, this research pioneers a comprehensive approach that integrates the warping stiffness of supports into the structural analysis. Through the introduction of novel coefficients—warping (0.377–0.484) and bending (0.616–0.672)—this study established a new paradigm in the design and stability analysis of thin-walled beams. Our findings reveal that incorporating support warping stiffness can dramatically increase normal stresses by 2–4 times within the span, a revelation that significantly alters existing design assumptions. The study also demonstrated how sectorial stiffness, a key parameter, directly enhances the warping stiffness of the supports, while the bending stiffness of the beam has negligible impact on the compliance factor. This novel insight provided a substantial leap forward in accurately predicting the complex interaction between bending and torsion in lightweight steel structures. By addressing a critical gap in the literature, this research not only advances the theoretical understanding of thin-walled profiles but also offers practical implications for optimizing the structural design of modern construction systems, enhancing both performance and safety. • A method was developed for determining the bimoment in beams with support warping stiffness. • A method is proposed for determining the actual reference values of the bending moment and bimoment from numerically obtained values of the reference normal stresses. • Range of values of the coefficients are revealed, considering warping and bending finite stiffness of thin-walled profiles, for the case when stud profiles are supported inside track profiles of various thicknesses and high of 150 mm. • With an increase in the sectorial stiffness of the profile, the support warping stiffness increases, while with increase in bending stiffness of the beam, the compliance bending factor of the support changes insignificantly. • Considering the warping stiffness of the support connection leads to an increase in the obtained normal stresses in the span of a thin-walled profile by 2-4 times, depending on the sectorial stiffness of the profile. [ABSTRACT FROM AUTHOR]

• A finite deformation peridynamics (PD) beam theory is developed to capture warping. • A new bond breaking criterion is proposed for PD beam theory. • Numerical implementation strategy is presented for quasi-static and dynamic cases. • Simulations reveal that the lattice geometry and loading direction influence the warping amplitude. This paper presents a finite deformation beam model based on Simo-Reissner theory in peridynamics (PD) framework to deal with torsion induced warping deformation. Seven degrees of freedom, viz. three translational, three rotational, and one warping amplitude are considered at each material point. The governing equations of the beam are obtained by employing global balance of linear and angular momenta in conjunction with Simo's assumption on the deformation field. The relation between PD resultant force, moment, bi-moment, and bi-shear states with their classical counterparts is established using the constitutive correspondence method. Numerical implementation strategy is furnished for both quasi-static and dynamic cases. The solution for quasi-static load is obtained through the Newton-Raphson method. The proposed model is validated against finite element solutions considering cantilever beam and lattice structures. Quasi-static deformation responses of 3 × 3 × 3 octet and single unit compression-torsion lattice structures are presented further to demonstrate the effectiveness of proposed beam model. A new bond breaking criterion is proposed based on critical stretch, critical relative rotation, and critical relative warping amplitude and failure of the compression-torsion lattice structures under compressive load is simulated. The Newmark-beta method is utilized to solve the governing equations for dynamic loading. Numerical simulations include dynamic analysis of octet and compression-torsion lattice structures. [Display omitted] [ABSTRACT FROM AUTHOR]

Steel beams are susceptible to lateral-torsional buckling (LTB) failure when subjected to bending. Considering the effect of semi-rigid connections, the partial end restraints in torsion and warping can significantly influence the buckling behavior of members. However, these restraints are not properly simulated in the traditional line-finite-element method (LFEM), which may lead to an error in the estimation of member buckling capacity. To fill this gap, this research introduces an improved end-spring model into the formulation of an advanced co-rotational (CR)-LFEM, where the partial restraints in axial, bending, torsion, and warping degree of freedom (DOF) can be considered. A parametric study on the LTB behavior of steel beams is conducted using the modified CR-LFEM, where a series of elastic buckling analyses are conducted. The results show that the stiffness of partial torsion and warping restraints have a significant influence on the LTB capacity. The influence of various cross-section shapes and member slenderness ratios on the LTB behavior is also discussed. Finally, design recommendations are provided for classifying connection stiffness in torsion and warping DOF, offering guidelines for practitioners. In addition, the improved CR-LFEM with end-springs proposed in this study has been implemented into the educational software MSASect2. • Introduced an improved end-spring model into an advanced co-rotational line-finite-element method. • The partial restraints in axial, bending, torsion, and warping degrees of freedom can be directly considered. • Performed parametric studies for the lateral-torsional buckling (LTB) of steel members with partial restraints. • Investigated the influence of member geometry and connection stiffness on the LTB capacity of beams. • Proposed recommendations for classifying connection stiffness in torsion and warping. [ABSTRACT FROM AUTHOR]

This paper is concerned with the analysis of the pure torsion and distortion of straight box beams with trapezial cross-sections and hinged walls. A one-dimensional mechanical model for this kind of system subjected to anti-symmetric loads on the end cross-sections and no warping constraints is developed. The distortional stiffness of the system is provided by the torsional rigidity of the wall panels. The cross-sectional kinematic condition for which torsion and distortion are uncoupled has been determined. Novel explicit expressions of the internal and external distortional moments, the distortion constant, and the distortional warping pattern have been deduced; they can be directly translated to the classical distortion theory. Results of representative test cases with different section shapes and loads show excellent agreement with finite element models using shell elements. The model is a first step to analyse bridge decks with a distortionable central cell for wind engineering applications. Finally, an extension of the model, including the distortional stiffness provided by the frame bending stiffness of the cross-section walls, is presented. The extended model is applicable to assess the large-scale torsional–distortional effects in long beams with closed cross sections. [Display omitted] • 1D model for pure torsion and distortion of trapezial box beams with hinged walls. • The kinematic reference for uncoupling torsion and distortion has been determined. • Explicit formulas for distortional moment, distortion constant and warping pattern. [ABSTRACT FROM AUTHOR]

The structural response of soft-core sandwich beams of rectangular cross-section subjected to torsion is investigated. The paper uses the concepts of the extended high-order sandwich panel theory and generalizes the approach to account for the torsional response and its unique mechanisms. An analytical model that utilizes this generalized approach is formulated. The results of the model are presented and compared with the results of a reference model and a finite element analysis. Emphasis is placed on the torsional resistance mechanisms, their interaction, and the torsional-related localized effects. The results of the present model are in good agreement with the finite element analysis in terms of displacements and stresses, including the localized effects attributed to the soft-core. It is also shown that the present model can identify and quantify the localized effects while reference models available in the literature fail to do so. The results of the model contribute to the understanding of the torsional response of soft-core sandwich beams, including the transition between the warping and Saint-Venant torsional mechanisms and the localized effects associated with the soft-core and the application of boundary conditions to the different layers. [ABSTRACT FROM AUTHOR]

The out-of-plane buckling behavior of arches is closely related to the element torsional behavior. The traditional 12-degree-of-freedom second-order element stiffness matrix which uses a simplified element torsional stiffness GJ/ L (where G is the shear modulus, J the St. Venant torsion constant, L the element length) may significantly underestimate the out-of-plane buckling loads of funicular arches. This paper presents a simple and effective exact matrix stiffness method (MSM) for the out-of-plane buckling analysis of funicular arches. The developed MSM uses a 14-degree-of-freedom second-order element stiffness matrix of three-dimensional beam-columns considering both torsion and warping deformations. The out-of-plane buckling analysis of funicular arches is performed by using the global structural stability stiffness matrix, which combines the transformed second-order element stiffness matrices. The proposed MSM with the exact 14-degree-of-freedom second-order element stiffness matrix for the out-of-plane buckling analysis is verified by comparing with some classical solutions of funicular circular and parabolic arches with box sections and I-sections. Further discussions show that the 14-degree-of-freedom second-order element stiffness matrix may be reduced to a simplified 12-degree-of-freedom form only by deriving the exact element torsional stiffnesses, which could be significantly larger than GJ/ L for members with large cross-sectional torsional stiffness parameters (especially open cross-sections). [ABSTRACT FROM AUTHOR]

Based on an ethnographic study of non-conformist mosques, this article demonstrates how Muslims may adopt a Sunni or Shiʿa identity while navigating spaces that are institutionalised as such but give much less importance to this identity – if any – when occupying less structured spaces. It may, for example, have little influence on what religious literature they read, which preachers they follow on social media, and how they practise religion in everyday life. The article argues that research methodologies must be properly sensitised to this. Otherwise, they risk making the Sunni–Shiʿa identity hypervisible, thus producing the divide rather than investigating it. [ABSTRACT FROM AUTHOR]

The straight-beam approach is a simple and efficient means for analyzing the buckling of curved beams. Although previous researchers showed that the straight-beam approach is capable of simulating the lateral buckling of solid curved beams, the warping effect had been neglected and thus its practical application in engineering was limited. In this study, thin-walled curved I-beams will be dealt with by assuming the warping degrees of freedom (DOFs) to be identical at the common node for non-aligned connected elements. One feature of the present formulation is that the moments induced by initial nodal moments undergoing out-of-plane rotations are duly considered in the geometric stiffness matrix, while the compatibility and equilibrium are enforced for angled joints at the deformed position. With high computational efficiency, the present approach obtains buckling loads that agree well with the theoretical curved-beam solutions or the ones obtained by ABAQUS using shell elements. Compared with the modern curved-beam elements, the straight-beam element is locking free, invariant and simple in formulation, since the effect of curvature is not involved in global assembly. [ABSTRACT FROM AUTHOR]

In this paper, an accurate yet computationally efficient beam model based on hierarchical Legendre expansion functions is developed for the analysis of non-uniform or restrained torsion problems of Functionally Graded (FG) beams with solid or thin-walled section. The mechanical properties of the FG beams studied in this paper, such as Young's modulus and shear modulus, are assumed to continuously vary along either the length or thickness direction following a power-law distribution. The proposed beam model is based on the assumption that the beam's cross-section is infinitely rigid in its own plane. However, the longitudinal displacement field over the beam's cross-section is enriched in an element-wise manner by the unknown longitudinal displacement parameters multiplying with hierarchical Legendre expansion functions. The proposed modeling methodology has two novel aspects: First, it allows the torsional or twisting angle, which is a priori defined as an unknown kinematic variable, to be directly captured without a post-processing recovery step, even if there exists a strong flexual-torsional coupling within the beam; second, the longitudinal warping response of the beam, triggered by stretching, bending, twisting, or the coupling between them, can be captured without the pre-determination of warping modes and at a lower level of DOFs. The strong-form governing equations of non-uniform or restrained torsion problems of the FG beam are derived based on the principle of minimum potential energy and is directly solved by the high-quality general-purpose ordinary differential equation (ODE) solver, i.e. COLSYS ODE solver. Also, a more efficient Rayleigh-Ritz energy method is applied to provide the weak-form solutions. The resulting beam model is suitable to a more general cross-section, such as solid section, branched open section, or half open-half closed section. The accuracy and efficiency of the proposed beam model are validated extensively by comparing with the previously published results in literature. Effects of the power-law index, taper ratio, and section-type on the torsional response of FG beams with material gradation along length or thickness direction are studied with various numerical examples. [ABSTRACT FROM AUTHOR]

Straight elements are a simple tool for tackling the locking problem for curved beams. When a curved I-beam is approximated by chordwise straight elements, the conventional approach is to treat the rate of twisting as the warping degree of freedom (DOF) for the chordwise elements, which involves some confusion. In this article, a new straight element was derived by a mixed formulation by adopting the generalized warping deformation used in the energy composition as the associated nodal DOF based on the Bernoulli-Euler-Vlasov hypothesis. The convergence characteristics of both approaches were theoretically analyzed. The example demonstrated good convergence properties for both the conventional and mixed straight elements, aside from the fact that they are locking-free, unlike some curved elements. The mixed straight element showed a better performance because its treatment of warping deformation is more consistent in energy terms. [ABSTRACT FROM AUTHOR]

YAG wafers are the most host laser crystals used for high-power lasers, which are usually machined by grinding to meet the required accuracy for laser components. Warping deformation induced by the residual stress is one of the main damages for YAG wafers after the grinding process, which will seriously decrease the service accuracy and life of the lasers. Developing theoretical model of warping deformation is of great significance to achieving the ultra-precision machining of YAG wafers. The cutting depth of single abrasive and grinding force in self-rotating grinding were investigated by considering the kinematic trajectory of abrasives, brittle-to-ductile transition, elastic mechanics, elastic deformation of the grinding wheel and strain rate effect. A theoretical model of warping deformation in self-rotating grinding of YAG wafers was developed based on the cutting depth and grinding force. The influence of subsurface damage and residual stress on warping deformation was analyzed based on the theoretical model and finite element simulation. Self-rotating grinding tests of YAG wafers were performed, and the results showed that the warping deformation decreased as the wheel rotational speed increased, and increased as the abrasive size, workpiece rotational speed and feed speed increased. The experimental results agreed well with the simulated results of the theoretical model, indicating that the theoretical model can accurately predict the warping deformation induced by self-rotating grinding process. This work will not only enhance the understanding of the essence of the wafer warping induced by ultra-precision machining, but also provide a guide for optimizing the processing parameters in self-rotating grinding of YAG wafers. [ABSTRACT FROM AUTHOR]

This paper presents the use of a finite element method (FEM) to analyze the shear lag effect due to the flexure of beams with an arbitrary cross-section and homogeneous elastic material. Beams are constrained by the most common types of supports, such as fixed, pinned, and roller. The transverse, concentrated, or distributed loads act on the beams through the shear center of the cross-section. The presented FEM transforms the 3D analysis of the shear lag phenomenon into separated 2D cross-sectional and 1D beam modeling. The characteristics of the cross-section are firstly derived from 2D FEM, which uses a 9-node isoparametric element. Then, a 1D FEM, which uses a linear isoparametric element, is developed to compute the deflection, rotation angle, bending warping parameter, and stress resultants. Finally, the stress field is obtained from the local analysis on the 2D-cross section. A MATLAB program is executed to validate the numerical method. The validation examples have proven the efficiency and reliability of the numerical method for analyzing shear lag flexure, which is a common problem in structural design. [ABSTRACT FROM AUTHOR]

Specialty thermoplastic materials based on fluoropolymer polyvinylidene fluoride (PVDF) became commercially available to the 3D printing community only recently. Additive manufacturing of PVDF-based structural components suited for harsher operational conditions is important for more demanding industrial sectors such as biomedical/chemical, aerospace, or automotive. Such components must ensure adequate mechanical performance in diverse deformation cases. Hence, this paper reports on fused filament fabrication (FFF) and quasi-static tensile, flexural and compressive testing of PVDF homopolymer, biocompatible PVDF-co-hexafluoropropylene (PVDF-HFP) copolymer, and static-dissipative PVDF-HFP/graphene composite specimens, which were printed with triangular lattice infill of variable density for addressing the influence of lightweighting. Printability in an open-chamber-based FFF machine is discussed in terms of part warpage and adhesion issues, which aggravate FFF process because of the higher degree of crystallinity, larger coefficient of thermal expansion, and hydrophobicity of PVDF. It was found that these printing complications are alleviated by applying lower printing speed and temperature together with the use of wider brims and a specialized FFF-tailored adhesive. The measured stress–strain curves are examined to analyze changes in strengths and moduli of elasticity of the specimens as a function of infill density including comparisons in ductility, failure mode, and anisotropic mechanical behavior such as tension–compression asymmetry. The presented results serve as a guideline for additive manufacturing of functional PVDF-based load-bearing components that are intended for service in different loading regimes. [ABSTRACT FROM AUTHOR]

The beam–column element analysis method has been extensively adopted in practice, relying on the robustness of its element formulation. Steel members with open sections are commonly used; their cross-sectional shapes are usually nonsymmetric to improve material efficiency. Nevertheless, an offset exists between the shear center and the centroid of a nonsymmetric section. If the applied loads do not act at the shear center, torsion can be induced; this is sometimes unavoidable. When a member is subject to torsion, the inclined angle between the local axes of the cross section and the element is varied along the element length, complicating the summating of the cross section's stiffness to form an element stiffness matrix. This study developed a new beam–column element formulation based on the nonsymmetric section assumption and a Gaussian quadrature procedure to formulate the element stiffness matrix of being concise in expressing formulation. The updated Lagrangian method was modified to consider large deflections. This method permitted the use of fewer elements to simulate a member under torsion, leading to a significant improvement in numerical efficiency. Detailed derivations and verification examples are given in the paper. [ABSTRACT FROM AUTHOR]

In this paper, the static response and normal/shear stresses of axially functionally graded exact super-elliptical beams are presented via a warping-included mixed finite element method. Super-elliptical axis geometry is derived over the exact functions of planar curves. The constitutive equations are obtained from three-dimensional elasticity theory. The mixed finite element formulation is enhanced by including the warping deformations via displacement-type finite elements on the cross-section. The two-noded curved mixed finite element has twenty-four degrees of freedom in total. Satisfactory results are obtained for the warping-included normal/shear stresses, displacements and reactional forces of axially functionally graded exact super-elliptical beams even with lesser degrees of freedom compared to the three-dimensional behavior of brick finite elements. As benchmark examples, the influences of high axial curvature, cross-sectional geometry and material gradation on the static response and stresses of axially functionally graded exact super-elliptical beams are investigated. [ABSTRACT FROM AUTHOR]

This article presents a new higher-order beam model. The present beam model is governed by differential equations that are similar to those present in some existing higher-order beam models; however, the present beam model makes use of a novel method of calculating the transverse shear stiffness, which facilitates the calculation of a shear-warping stiffness without the need for an assumed warping displacement field, and without introducing any additional kinematic variables. The present beam model also facilitates the recovery of the distributions of longitudinal normal stresses and transverse shear stresses. The authors postulate that the bending and shear terms in first-order shear deformation theory represent the first two terms in an infinite series that would constitute an ideal one-dimensional beam model, and it is suggested that the present beam model constitutes the first four terms in this hypothetical infinite series. The present beam model is solved for several example beams, and the results are compared with those of existing classical and higher-order beam models, as well as computational results from finite element analyses. It is shown that the present beam model is able to accurately represent deformed shapes and stress distributions pertaining to beams that exhibit non-trivial shear compliance as well as non-trivial shear-warping stiffness. In the case of laminated composite beams comprising a large number of laminae, the present beam model offers a level of analytical fidelity that is comparable to that of existing zigzag beam models; however, unlike zigzag beam models, the present beam model is equally well suited for the analyses of beams comprising any number of laminae. [ABSTRACT FROM AUTHOR]

The microwire torsion experiment holds significant importance in assessing the size effect at the micron and submicron scales. This paper introduces a model that examines the torsion of a microwire within a higher-order phenomenological strain gradient plasticity framework. The energetic consequences of plastic strain gradient are captured through a multi-term Chaboche-type nonlinear higher-order energetic stress evolution. This higher-order stress is linked to the formation of geometrically necessary dislocations (GNDs) and reaches saturation as effective plastic strain increases during plastic flow. The thermodynamically consistent framework demonstrates additional dissipation in the dissipation inequality. To simulate microwires, a comprehensive three-dimensional mixed finite element with displacement and plastic strain as variables is proposed. Subsequently, an axisymmetric version of the general 3D theory is derived for circular cross-sections using the micro-force balance equation, which takes into account both energetic and dissipative higher-order stress. A procedure for identifying hardening parameters from experimental torque-twist data is suggested. Comparative analysis between numerical responses and experimental observations highlights the effectiveness of saturation term(s) in the higher-order energetic stress evolution equation, as well as the influence of radius-dependent hardening parameters. The torsional behavior of a non-circular section indicates that the warping of the non-circular section diminishes with an increased strain gradient effect. Surface passivation enhances the wire's strength by preventing GNDs from escaping the surface. However, non-uniform surface passivation disrupts the symmetry of the cross-section and leads to more warping. • Proposal to assess size-dependent 3D torsion using a novel kinematic hardening rule. • An semi-analytical formulation is proposed and compared with the 3D FEM solution. • Proposal for identifying multi-term kinematic hardening parameters from experiment. • Kinematic hardening with equal L/R ratio can better predict the experiment. • Assessing torsion of non-circular section with nonuniform surface passivation. [ABSTRACT FROM AUTHOR]

This study deals with the analysis of multilayer composite and functionally graded materials (FGM) structures. The material properties of the FGM beam are assumed to vary according to the power law distribution of its constituent's volume fraction over the cross section. The analytical analysis seems to be cumbersome. A finite element approach is investigated in this work for the static and free vibration behaviors of the 2D FGM beams with variable constituents over the cross section. The analyses are carried out in arbitrary axes and the axial, bending and shear couplings are considered. In this study, the classical beam theory, Timoshenko first-order and higher order shear models are described and implemented. The different models are compared to benchmark solutions found in the literature. Effects of boundary conditions, slenderness ratio, and the FGM power law parameter are investigated under static and free vibration analyses. FGM and multilayer sandwich beams are also analyzed. It is proven that the axial bending and shear coupling affect the behavior of the FGM beams in both statics and dynamics. In the presence of short beams, shear effect is important and leads to cross-section warping. The classical beam theory fails in this context. All models are close in the case of slender beams. [ABSTRACT FROM AUTHOR]

Viewing various stereo images under different viewing conditions has escalated the need for effective object-level remapping techniques. In this paper, we propose a new object spatial mapping scheme, which adjusts the depth and size of the selected object to match user preference and viewing conditions. Existing warping-based methods often distort the shape of important objects or cannot faithfully adjust the depth/size of the selected object due to improper warping such as local rotations. In this paper, by explicitly reducing the transformation freedom degree of warping, we propose an optimization model based on axis-aligned warping for object spatial remapping. The proposed axis-aligned warping based optimization model can simultaneously adjust the depths and sizes of selected objects to their target values without introducing severe shape distortions. Moreover, we propose object consistency constraints to ensure the size/shape of parts inside a selected object to be consistently adjusted. Such constraints improve the size/shape adjustment performance while remaining robust to some extent to incomplete object extraction. Experimental results demonstrate that the proposed method achieves high flexibility and effectiveness in adjusting the size and depth of objects compared with existing methods. [ABSTRACT FROM AUTHOR]

Fine particulate matter, PM 2.5 , has been documented to have adverse health effects, and wildland fires are a major contributor to PM 2.5 air pollution in the USA. Forecasters use numerical models to predict PM 2.5 concentrations to warn the public of impending health risk. Statistical methods are needed to calibrate the numerical model forecast using monitor data to reduce bias and quantify uncertainty. Typical model calibration techniques do not allow for errors due to misalignment of geographic locations. We propose a spatiotemporal downscaling methodology that uses image registration techniques to identify the spatial misalignment and accounts for and corrects the bias produced by such warping. Our model is fitted in a Bayesian framework to provide uncertainty quantification of the misalignment and other sources of error. We apply this method to different simulated data sets and show enhanced performance of the method in presence of spatial misalignment. Finally, we apply the method to a large fire in Washington state and show that the proposed method provides more realistic uncertainty quantification than standard methods. [ABSTRACT FROM AUTHOR]

Torsional vibrations in beams are damped by discrete, axial viscous dampers in configurations constituting bimoments. The bimoments act on warping displacements and partial restraining of warping suggests the inclusion of a flexibility parameter, calibrated from numerical results. Correcting for distortion is incorporated in a similar manner. The use of the governing differential equation with calibrated parameters as an alternative to a full complex analysis by a FE model is justified by an example. It is demonstrated that the differential equation determines the damped frequencies and damping ratios with great accuracy. Significant damping ratios of the lowest torsional mode are obtained. [ABSTRACT FROM AUTHOR]

The development of functional polymer parts with complex geometrical shape has been possible through additive manufacturing. In this research work, the issues such as warping, filament clogging, and layer delamination related to fused deposition modeling‐based 3D printing of nylon 6 are focused and its poor printability is improved. Nylon 6 is toughened by blending with an impact modifier, ethylene terpolymer. Complex viscosity, storage, and loss moduli of modified nylon increase significantly, which help to improve 3D printability of nylon 6. 3D printing of modified nylon is performed at optimized conditions, such as printing temperature, print speed, bed temperature, and cooling speed. Izod impact strength of 3D printed nylon 6‐based blend is observed ≈543 J m−1, which is significantly higher than the value (48 J m−1) available in literature for injection molded pristine nylon 6. Thermomechanical analysis of modified nylon shows higher coefficient of linear thermal expansion in normal direction as compared to that in flow direction, which is due to the orientation of polymer crystals during processing. The voids are observed on the cross‐sectional surface of impact fractured sample, which are responsible to produce light‐weight 3D printed specimens. [ABSTRACT FROM AUTHOR]

Many modern data sets require inference methods that can estimate the shared and individualspecic components of variability in collections of matrices that change over time. Promising methods have been developed to analyze these types of data in static cases, but only a few approaches are available for dynamic settings. To address this gap, we consider novel models and inference methods for pairs of matrices in which the columns correspond to multivariate observations at different time points. In order to characterize common and individual features, we propose a Bayesian dynamic factor modeling framework called Time Aligned Common and Individual Factor Analysis (TACIFA) that includes uncertainty in time alignment through an unknown warping function. We provide theoretical support for the proposed model, showing identiability and posterior concentration. The structure enables efficient computation through a Hamiltonian Monte Carlo (HMC) algorithm. We show excellent performance in simulations, and illustrate the method through application to a social mimicry experiment. [ABSTRACT FROM AUTHOR]

In injection molding processes for thermoplastic parts, the polymer solidification phase in the molding cavity has a strong influence on the quality of the shaped parts and also on the process cycle time. Reducing cycle time is one of the major concerns for plastic injection industries. As cooling phase presents the most critical phase to get quality and cycle time of the part, the application of additive manufacturing (AM) technologies has been overcoming the limitations of traditional cooling system design. AM enables the construction of conformal cooling channels for higher cooling uniformity due to its almost unlimited freedom of design that can fulfil the desired functions in injection molding process equipment. The analysis of the heat transfer during the phase of cooling allows the investigation of the optimal positioning of the cold sources and their intensities. In this paper, a systematic approach is used to replace conventional channels in an injection molding tool with conformal cooling channels. A simulation is used to develop a numerical model that describes the heat transfer and predicts the cycle time of both the optimal and conventional designs. Finally, a numerical comparison is made between traditional and conformal cooling to demonstrate the beneficial effect on reducing the manufacturing cycle and enhancing part quality. [ABSTRACT FROM AUTHOR]

The paper presents the development of a three-dimensional (3D) beam element for the analysis of steel structures in fire that properly accounts for the degradation of the torsional strength and stiffness owing to thermal exposure. The element is well-suited for the analysis of members that are subjected to significant torsional effects, as steel members with open cross-sections subjected to torsion, lateral-torsional buckling, and torsional buckling. The element is based on a corotational formulation and small strains assumption, while the local formulation was developed according to both the Timoshenko and Bernoulli beam theories. The stress-strain relationship and thermal expansion of steel were implemented according to Eurocode EN 1993-1-2 (CEN 2005). A comprehensive numerical analysis was performed and results for several case studies are presented in the paper to assess the performance of the 3D beam element. The outcomes indicated very good agreement when compared with shell-based models, highlighting promising capabilities of modeling steel structures in fire. Moreover, the proposed element showed more accurate results with respect to beam elements included into two commercial software, i.e., ABAQUS and SAFIR. [ABSTRACT FROM AUTHOR]

We investigate two crucial and closely-related aspects of CNNs for optical flow estimation: models and training. First, we design a compact but effective CNN model, called PWC-Net, according to simple and well-established principles: pyramidal processing, warping, and cost volume processing. PWC-Net is 17 times smaller in size, 2 times faster in inference, and 11 percent more accurate on Sintel final than the recent FlowNet2 model. It is the winning entry in the optical flow competition of the robust vision challenge. Next, we experimentally analyze the sources of our performance gains. In particular, we use the same training procedure for PWC-Net to retrain FlowNetC, a sub-network of FlowNet2. The retrained FlowNetC is 56 percent more accurate on Sintel final than the previously trained one and even 5 percent more accurate than the FlowNet2 model. We further improve the training procedure and increase the accuracy of PWC-Net on Sintel by 10 percent and on KITTI 2012 and 2015 by 20 percent. Our newly trained model parameters and training protocols are available on https://github.com/NVlabs/PWC-Net. [ABSTRACT FROM AUTHOR]

All glass structure for the tower closure of the Pützerturm at TU Darmstadt More than 75 years ago, the Pützerturm closure of the clock tower of the Technische Universität Darmstadt was destroyed in the night of the fire on September 11 1944. Since then, the former clock tower presents itself as a stump at the central location of the university. Following the architectural design by Walter & Sichau Architects, the tower now has a new closure in a modern design language. The structure, designed as a fall‐protecting all‐glass construction, takes up the adaptations to the structural changes of the post‐war period and thus blends into the building ensemble. The construction, reduced to only four large‐format glass elements, each weighing about 2 t, follows the trend towards larger and larger all‐glass applications. In the present article, the construction characteristics are shown and, using this example, the object‐specific deviations from the technical building regulations and the essentially associated necessary proofs are shown, which ultimately made a project‐related construction technique permit (vBG) possible. [ABSTRACT FROM AUTHOR]