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Corrugated panels possess excellent thermomechanical properties, but, with presently no hygrothermal applications for building envelopes, their full potential still needs to be explored. This study characterized the physical properties of three biobased corrugated compositions to identify potential building applications. Flat samples of the same compositions were analyzed for certain properties to aid in understanding. As this characterization is groundbreaking, the testing was based on or inspired by established standards. Results suggest that the panels with two wood veneer cores and two kraft paper surfaces coated with polymers are the most promising, as such structures are less sensitive to water and possess a good moisture buffer value that should be advantageous for building construction. Corrugated panels are particularly interesting because their inner materials have properties comparable to those of conventional wood-based panels such as plywood. However, the apparent properties of corrugated panels become one to ten times smaller or larger, which opens up new design possibilities for building envelope applications.

A wood-based sandwich panel with a corrugated core was developed as a building material. A matched-die mold manufactured from commercial plywood was used to fabricate the corrugated panels through a cold-forming process. A cold-setting resin was applied on southern yellow pine (Pinus spp.) veneers with an average thickness of 4 mm, and four plies of them were formed into a corrugated geometry using a wooden mold. When the resin was cured, the corrugated panel of veneers retained the corrugated shape after load removal. Facesheets of the sandwich structures were fabricated using three plies of the same veneers. To evaluate the effect of this corrugated geometry on the structural performance, the same veneers — regarding number, thickness, and orientation — used for the sandwich panel were adopted to fabricate laminated flat panels. Both sandwich and laminated flat panels were submitted to a four-point bending test. The results confirmed the sandwich effect, i.e. a 1741% increase in the bending stiffness of sandwich panels compared to that of laminated flat panels. Sandwich panels developed in this study were compared to Structural Insulated Panels (SIPs), wood-framed structures known as stud walls, and sandwich panels produced using a hot-pressing technique. The cold-formed sandwich panels had higher structural performance than commercial building materials.

A wooden matched-die mold was manufactured to develop wood-based corrugated panels. Wood veneers brushed with resin were cold pressed between the mold halves and formed into a corrugated geometry. The corrugated panels were used as a core and bonded to flat veneer-based facesheets to develop sandwich panels. The whole manufacturing process involved a cold-forming technique that allowed panels to be produced with no heat. Specimens cut from both corrugated and sandwich panels were submitted to a four-point bending test to evaluate their structural performance. Adopting the same number of layers used to make the sandwich panels, flat panels were fabricated and tested to find the effect of this corrugated geometry and cold-forming process on the load-carrying capacity of the sandwich structures. A comparison with flat panels made with the same stacking of veneers showed an increase of 272% of the bending stiffness of the sandwich panels, which is known as the sandwich effect. Comparison between the bending results of the panels developed in this study with those manufactured using thermoset resin and hot-pressing technique indicated that the cold-forming process using the wooden mold is an effective and inexpensive method to develop wood-based corrugated sandwich panels.

Corrugated panels possess excellent thermomechanical properties, but, with presently no hygrothermal applications for building envelopes, their full potential still needs to be explored. This study characterized the physical properties of three biobased corrugated compositions to identify potential building applications. Flat samples of the same compositions were analyzed for certain properties to aid in understanding. As this characterization is groundbreaking, the testing was based on or inspired by established standards. Results suggest that the panels with two wood veneer cores and two kraft paper surfaces coated with polymers are the most promising, as such structures are less sensitive to water and possess a good moisture buffer value that should be advantageous for building construction. Corrugated panels are particularly interesting because their inner materials have properties comparable to those of conventional wood-based panels such as plywood. However, the apparent properties of corrugated panels become one to ten times smaller or larger, which opens up new design possibilities for building envelope applications. [ABSTRACT FROM AUTHOR]

A wood-based sandwich panel with a corrugated core was developed as a building material. A matched-die mold manufactured from commercial plywood was used to fabricate the corrugated panels through a cold)forming process. A cold-setting resin was applied on southern yellow pine (Pinus spp.) veneers with an average thickness of 4 mm, and four plies of them were formed into a corrugated geometry using a wooden mold. When the resin was cured, the corrugated panel of veneers retained the corrugated shape after load removal. Facesheets of the sandwich structures were fabricated using three plies of the same veneers. To evaluate the effect of this corrugated geometry on the structural performance, the same veneers — regarding number, thickness, and orientation — used for the sandwich panel were adopted to fabricate laminated flat panels. Both sandwich and laminated flat panels were submitted to a four-point bending test. The results confirmed the sandwich effect, i.e. a 1741% increase in the bending stiffness of sandwich panels compared to that of laminated flat panels. Sandwich panels developed in this study were compared to Structural Insulated Panels (SIPs), wood)framed structures known as stud walls, and sandwich panels produced using a hot-pressing technique. The cold-formed sandwich panels had higher structural performance than commercial building materials. [ABSTRACT FROM AUTHOR]

A wooden matched-die mold was manufactured to develop wood-based corrugated panels. Wood veneers brushed with resin were cold pressed between the mold halves and formed into a corrugated geometry. The corrugated panels were used as a core and bonded to flat veneer-based facesheets to develop sandwich panels. The whole manufacturing process involved a cold-forming technique that allowed panels to be produced with no heat. Specimens cut from both corrugated and sandwich panels were submitted to a four-point bending test to evaluate their structural performance. Adopting the same number of layers used to make the sandwich panels, flat panels were fabricated and tested to find the effect of this corrugated geometry and cold-forming process on the loadcarrying capacity of the sandwich structures. A comparison with flat panels made with the same stacking of veneers showed an increase of 272% of the bending stiffness of the sandwich panels, which is known as the sandwich effect. Comparison between the bending results of the panels developed in this study with those manufactured using thermoset resin and hot-pressing technique indicated that the cold-forming process using the wooden mold is an effective and inexpensive method to develop woodbased corrugated sandwich panels. [ABSTRACT FROM AUTHOR]

• 3-panel Frameless CFSCW works as both axial and lateral load-resisting system in low rise long span Frameless buildings. • The failure modes of the 3-panel Frameless CFSCW consist of buckling of the wall panels, distortion of footing channel, and connection damage. • The proposed finite element model can be used to simulate the force-displacement curve before buckling and display damage patterns of Frameless CFSCW effectively. • The ultimate shear capacity of 3-panel Frameless CFSCW is linearly correlated to the gauge thickness of the panel. The proposed equation shows an excellent match between the calculated results and the experiment results. The Frameless building system, developed by BEHLEN Industries LP, is a structural system that incorporates Cold Form Steel Corrugated Wall (CFSCW) components. These include walls, ceilings, and roofs formed by Frameless panels, along with footings, boundary columns, and an optional convex truss. The system employs simple bolt connections, enabling rapid construction without the need for heavy machinery. It is particularly cost-effective and is often utilized in regions with low seismic activity. In high seismic zones, the structural performance of The Frameless building system under combined compression and lateral loads has not been systematically examined. In this study, four full-scale 3-panel Frameless CFSCWs, were tested under combined axial and shear loads. A generic finite element model was proposed to simulate the force-deformation responses and deformed shapes of the 3-panel Frameless CFSCWs. The numerical simulation results were verified using the experimental results. The verified numerical model was then used in parameter study to examine the ultimate shear capacity of 3-panel Frameless CFSCW of different wall thickness, with the presence of axial compression. The results of the study revealed the ultimate shear capacity of 3-panel Frameless CFSCW is linearly correlated with gauge thickness of the wall panel. [ABSTRACT FROM AUTHOR]

A novel superimposed sine-wave (SSW) structure was designed and fabricated by selective laser melting (SLM) in this work. The energy absorption performance, deformation modes, and fracture mechanism of heat-treated SSW components under compression were studied. The formability was analyzed and the results showed that the SLM fabricated SSW components possessed nearly dense microstructure and smooth surface morphology. The numerical simulation model was established to show the stress distribution and deformation mechanism during compression, and the fracture morphologies of SSW components were investigated. Experimental results indicated that the SSW components exhibited a maximum crush force efficiency (CFE) of 73.06%, which was higher than most reported energy absorption structures. As the height of sinusoid 1 (H1) increased, the energy absorption (EA) and specific energy absorption (SEA) gradually increased to 37.73 J and 8.45 J/g, respectively. Simulation results revealed that the secondary trough had a large deformation during the compression process, which greatly enhanced the load uniformity of the structure. Fracture mode of SSW components was ductile fracture due to the post heat treatment. The SSW structures had the potential to be used in aerospace, protective armor, and automotive industries.

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Abstract In this paper, an integrated geometrically nonlinear aeroelastic framework to analyze the static nonlinear aeroelastic response of morphing composite wing with orthotropic materials has been developed. A flat plate/shell finite element, which can model plate-like wings, has been accommodated to model composite/corrugated panels to investigate effects of different laminate orientations and corrugations. A corotational approach is used to consider the geometrical nonlinearity due to large deformation produced by wing morphing. An unsteady vortex-lattice method is implemented to couple with the structural model subject to the large deformations. A homogenization method is also implemented to model corrugated panels as equivalent orthotropic plates. Individual structural, aerodynamic, and corrugated panel models, as well as the complete nonlinear aeroelastic framework, are verified. Numerical studies explore the static aeroelastic responses of a flat wing with composite/corrugated panels. This work helps to understand the nonlinear aeroelastic characteristics of composite/corrugated wings and demonstrates the capability of the framework to analyze the nonlinear aeroelasticity of such morphing wings. [ABSTRACT FROM AUTHOR]

Homogenization is a promising approach to capture the behavior of complex structures like corrugated panels. It enables us to replace high-cost shell models with stiffness-equivalent orthotropic plate alternatives. Many homogenization models for corrugated panels of different shapes have been proposed. However, there is a lack of investigations for verifying their accuracy and reliability. In addition, in the recent trend of development of smoothed finite element methods, the cell-based smoothed three-node Mindlin plate element (CS-MIN3) based on the first-order shear deformation theory (FSDT) has been proposed and successfully applied to many analyses of plate and shell structures. Thus, this paper further extends the CS-MIN3 by integrating itself with homogenization models to give homogenization methods. In these methods, the equivalent extensional, bending, and transverse shear stiffness components which constitute the equivalent orthotropic plate models are represented in explicit analytical expressions. Using the results of ANSYS and ABAQUS shell simulations as references, some numerical examples are conducted to verify the accuracy and reliability of the homogenization methods for static analyses of trapezoidally and sinusoidally corrugated panels. [ABSTRACT FROM AUTHOR]

Compliant structures, such as flexible corrugated panels and honeycomb structures, are promising structural solutions for morphing aircraft. The compliant structure can be tailored to carry aerodynamic loads and achieve the geometry change simultaneously, while the reliability of the morphing aircraft can be guaranteed if conventional components and materials are used in the fabrication of the morphing structure. In this article, a compliant structure is proposed to change the dihedral angle of a morphing wingtip. Unsymmetrical stiffness is introduced in the compliant structure to induce the rotation of the structure. Trapezoidal corrugated panels are used, whose geometry parameters can be tailored to provide the stiffness asymmetry. An equivalent model of the corrugated panel is employed to calculate the deformation of the compliant structure. To provide the airfoil shape, a flexible honeycomb structure is used in the leading and trailing edges. An optimisation is performed to determine the geometry variables, while also considering the actuator requirements and the available space to instal the compliant structure. An experimental prototype has been manufactured to demonstrate the deformation of the morphing wingtip and conduct basic wind tunnel tests. [ABSTRACT FROM AUTHOR]

The structural behaviour of nano-structured materials produced by surface mechanical attrition treatment (SMAT) method under three-point bending is explored in this study. Theoretical models are developed to analyse beams of rectangular and corrugated cross-sections in elastic and inelastic bending. In these models, several material parameters are determined by curve fitting between analytical calculations and experiments. AISI 304 stainless steel sheets of selected thicknesses and corrugated panels with and without SMAT are designed, manufactured and tested. The experimental investigation reveals that the combination of corrugated shape and SMAT method gives the most significant increase in terms of bending stiffness, strength and hardening. [ABSTRACT FROM AUTHOR]

The behavior analysis of complex structures like corrugated panels usually requires high-cost shell modeling which is an obstacle in subsequent studies such as parametric study and optimization. To overcome the difficulty, many homogenization models in which equivalent orthotropic plates replaces the original shells have been proposed. However, there is a lack of investigations for verifying their accuracy and reliability. In this paper, the cell-based smoothed three-node Mindlin plate element (CS-MIN3) based on the first-order shear deformation theory (FSDT) is integrated with typical homogenization models to give some homogenization methods for free vibration analyses of trapezoidally and sinusoidally corrugated panels. Using the results of ANSYS and ABAQUS shell simulations as references, the accuracy and reliability of the homogenization methods are illustrated through several numerical examples. The influences of geometric parameters such as the number of corrugation units, corrugation amplitude, trough angle, and panel thickness are studied and some important remarks about the performances of these methods are derived. [ABSTRACT FROM AUTHOR]

One of the key problems in the development of morphing aircraft is the morphing structure, which should be able to carry loads and change its geometry simultaneously. This paper investigates a compliant structure, which has the potential to change the dihedral angle of morphing wing-tip devices. The compliant structure is able to induce deformation by unsymmetrical stiffness allocation and carry aerodynamic loads if the total stiffness of the structure is sufficient.The concept has been introduced by building a simplified model of the structure and deriving the analytical equations. However, a properly designed stiffness asymmetry, which is optimised, can help to achieve the same deformation with a reduced actuation force.In this paper, round corrugated panels are used in the compliant structure and the stiffness asymmetry is introduced by changing the geometry of the corrugation panel. A new equivalent model of the round corrugated panel is developed, which takes the axial and bending coupling of the corrugated panel into account. The stiffness matrix of the corrugated panel is obtained using the equivalent model, and then the deflections of the compliant structure can be calculated. The results are compared to those from detailed finite element models built in the commercial software Abaqus. Samples with different geometries were manufactured for experimental tests.After verifying the equivalent model, optimisation is performed to find the optimum geometries of the compliant structures. The actuation force of a single compliant structure is first optimised, and then the optimisation is performed for a compliant structure consisting of multiple units. A case study is used to show the performance improvement obtained. [ABSTRACT FROM PUBLISHER]

In this paper, modification of an existing equivalent model of the corrugated panel is investigated. The axial and bending coupling of the corrugated panel supplements the previous equivalent properties when the corrugated panel has a fixed boundary condition. The analytical expressions of the coupling vertical deflections are obtained and verified by the finite element method. A method to eliminate the vertical deflection is proposed, and the importance of the coupling effect is demonstrated by the application of the modified model in a compliant structure. [ABSTRACT FROM AUTHOR]

Numerous papers deal with the Equivalent Plate Model (EPM) for corrugated panels. Comparison of published formulas for the four relevant equivalent bending stiffnesses D 11 eq , D 22 eq , D 66 eq , and D 12 eq revealed ambiguities: Three different formulas were found for D 22 eq , which describes the bending of the ridges and troughs; for D 66 eq two ‘competing’ formulas emerged. Expressions not converging to the flat-plate values in the limit of vanishing corrugation height were discarded. All discussed formulas are written in a uniform notation for general one-dimensionally periodic shapes. Formulas derived for isotropic panel materials were generalized to the orthotropic case. In order to resolve the ambiguities and assess the EPM with regard to its range of applicability, vibration modes of six rectangular corrugated panels were measured. While agreement with numerical results obtained with COMSOL was fair, the EPM predictions of natural frequencies were satisfactory only for low-order modes. Finally, equivalent bending stiffnesses were determined numerically from COMSOL results for a few low-order modes by inverse methods. Thus the ambiguities with regard to D 22 eq and D 66 eq could be resolved. However, the D 12 eq values determined numerically came out significantly larger than the EPM prediction, in particular for stronger corrugations. Even though this discrepancy had little effect on the natural frequencies tested in the present paper, it remains a theoretical challenge. [ABSTRACT FROM AUTHOR]

The structural weight of a shell-plated structure can be reduced in numerous ways. The current investigation presents an example of innovative lightweight design of the pontoon of an offshore platform by utilisation of corrugated structure. Corrugated shell plating is compared with a conventional stiffened panel with respect to strength, weight and cost. For this purpose, an optimisation methodology is developed for shell-plated marine structures. The procedure enables the analysis/comparison of various (structural) solutions with regard to strength characteristics, weight and cost. Here, strength characteristics include ultimate tensile strength, buckling stability and fatigue life analyses. Linear elastic finite-element analyses are carried out to generate input to the structural characteristics studies, which involve several design criteria according to classification rules. The results show that in competition with the traditional stiffened panel, corrugated shell-plated structure can be used as the more lightweight design solution. It can be manufactured and installed at a lower cost. Finally, the structural strength characteristics analyses show that, when designed properly, ABS and DNV classification rules are fulfilled without compromising with the safety margins. [ABSTRACT FROM PUBLISHER]

Abstract: The design of corrugated panels has wide application in engineering. For example corrugated panels are often used in roof structures in civil engineering. More recently corrugated laminates have been suggested as a good solution for morphing aircraft skins due to their extremely anisotropic behaviour. The optimal design of these structures requires simple models of the panels or skins that may be incorporated into multi-disciplinary system models. Thus equivalent material models are required that retain the dependence on the geometric parameters of the corrugated skins or panels. An homogenisation-based analytical model, which could be used for any corrugation shape, is suggested in this paper. This method is based on a simplified geometry for a unit-cell and the stiffness properties of original sheet. This paper outlines such a modelling strategy, gives explicit expressions to calculate the equivalent material properties, and demonstrates the performance of the approach using two popular corrugation shapes. [Copyright &y& Elsevier]

Abstract: Corrugated panels are commonly used as blast walls on offshore installations, and an assessment of their response to dynamic pressure loads needs to be made during design. Although detailed numerical models are commonly used, simplified models based on spring-mass idealisations, such as Biggs’ method, are still important for preliminary design. Based on an earlier static formulation, the dynamic response of a corrugated panel (as characterised by its central deflection) subjected to a uniformly distributed pressure pulse is analysed. A simplified theoretical method is built up and new transformation factors for panels with straight endplates are derived. The method is calibrated against corresponding finite element and experimental results. Good agreement is achieved. [Copyright &y& Elsevier]

• New Rotatable Hopkinson Bar is used for dynamic shear-compression on corrugated sandwich panel. • Three deformation modes of corrugations are identified for different loading conditions. • Loading rate effect under various combined loading is examined and attributed to inertia effect. This paper studies the quasi-static and dynamic mechanical behaviors of a commercial corrugated sandwich panel under combined shear-compressive loading by using a modified MTS machine and the so-called Rotatable Hopkinson Bar (RHB) loading system. Particular focus is placed on identifying the differences of large deformation behaviors of corrugation panels between uniaxial compression and combined shear-compression, especially the influences of shear-compressive loading angle and loading rate on the stress-displacement curves and the deformation modes. It is found that the normal stress decreases with the loading angle, while the shear stress increases with it for both the quasi-static and dynamic loadings. Three deformation patterns are identified for five different loading angles from 0o (corresponding to uniaxial compression) to 50o. A positive loading rate effect is found for the initial collapse of corrugated panels, which is contributed to the inertia effect within corrugation buckling. The strength of the panels after initial collapse shows a negative loading rate effect, which may be due to the strain softening behavior of base material (5754-H48 Aluminum alloy) at impact loading. [ABSTRACT FROM AUTHOR]

A novel superimposed sine-wave (SSW) structure was designed and fabricated by selective laser melting (SLM) in this work. The energy absorption performance, deformation modes, and fracture mechanism of heat-treated SSW components under compression were studied. The formability was analyzed and the results showed that the SLM fabricated SSW components possessed nearly dense microstructure and smooth surface morphology. The numerical simulation model was established to show the stress distribution and deformation mechanism during compression, and the fracture morphologies of SSW components were investigated. Experimental results indicated that the SSW components exhibited a maximum crush force efficiency (CFE) of 73.06%, which was higher than most reported energy absorption structures. As the height of sinusoid 1 (H 1) increased, the energy absorption (EA) and specific energy absorption (SEA) gradually increased to 37.73 J and 8.45 J/g, respectively. Simulation results revealed that the secondary trough had a large deformation during the compression process, which greatly enhanced the load uniformity of the structure. Fracture mode of SSW components was ductile fracture due to the post heat treatment. The SSW structures had the potential to be used in aerospace, protective armor, and automotive industries. Unlabelled Image • A novel superimposed sine-wave structure was designed and fabricated by selective laser melting. • The load uniformity of superimposed sine-wave structure was higher than most reported energy absorption structures. • The unique second trough of superimposed sine-wave structure was the main reason for improving load uniformity. [ABSTRACT FROM AUTHOR]

Extensive studies have been carried out on the acoustic performance of a micro-perforated panel (MPP) absorber which typically consists of a flat MPP fitted in front of a rigid backing wall. The present study concerns its acoustic properties when the conventionally flat perforated panel is replaced with a corrugated one that finds many applications in architecture. A three-dimensional finite element model is used to simulate the acoustic performance of a such corrugated MPP absorber at normal incidence, oblique incidence and diffuse field. Results show that the absorption performance of corrugated MPPA can be very different from conventional flat MPPA when the acoustic wave length is smaller than the corrugation depth. At low frequencies, the corrugated MPP performs similarly as a flat one of the same bulk perforation ratio. The absorption levels of the corrugated MPPA are considerably enhanced at the dips of absorption curves, which is favorable for reverberation control or broadband random noise reduction in large spaces and buildings. Further modal analysis shows that multiple modes of the corrugated configuration are excited at the peak and dip frequencies, and the acoustic response by the non-resonating modes give rise to the performance improvement. Absorption coefficients are also measured experimentally using an impedance tube. The measured normal incidence absorption coefficients compare well with the numerical predictions, which validates the numerical model and, in part, the numerical findings. [ABSTRACT FROM AUTHOR]

Corrugated panels have many potential applications in civil, mechanical and aerospace engineering. The research on morphing aircraft requires the derivation of deformation limits of corrugated panels, which can be used as the constraint conditions for the design and optimisation of morphing structures. The relationship between the local and global strains of the equivalent models for corrugated panels is derived, which makes the prediction of the maximum strain available. Thus, from the maximum strain criterion, the global strain limit is evaluated under different load conditions. The results from the proposed analytical method are compared to those from detailed finite element models, which indicates a good agreement for all of the analysed cases. The influence of the geometric parameters of the corrugation shape is also investigated. [ABSTRACT FROM AUTHOR]