Response Of Panels Research Articles

Blast response and protection level of concrete composite wall panels made with recycled tyre fibres in a cement matrix

This paper investigates the blast response and protection level of a new blast-resistance wall panels made of Recycled Tyre Fibres Concrete (RTFC) as an exterior protective layer compositely connected to a concrete wall through experiments and numerical modelling. RTFC is a novel sustainable cement-based versatile composite, made with recycled non-biodegradable material (tyre rubber particles) in the form of composite fibres in a cement matrix, with applications in blast and ballistic protection that features high dynamic properties. Three composite wall panels were constructed and subjected to blast loads generated by Advanced Blast Simulator (ABS). Three different loading scenarios, each with an intensity capable of causing complete structural failure, were applied. The blast wave characteristics, such as the imposed overpressure and impulse, were measured alongside the deflection of the specimens. The wall specimens could withstand the blast loads with minimal damage. No cracks were observed in the RTFC layer, with only minor cracks appearing on the concrete side of the wall. The protection performance of the wall specimens was examined following UFC guidelines, revealing their outstanding resistance to blast loads. Moreover, in line with these guidelines, the composite wall panel is eligible for a High Level of Protection (HLoP) classification. Finally, a Single Degree of Freedom (SDOF) analytical model was developed for the wall panel to determine the Dynamic Increase Factor (DIF) of RTFC. The analysis resulted in a DIF value of 1.5, which was then incorporated into the numerical models of the walls. The accuracy of the DIF was validated by comparing the numerical results with experimental data, confirming its reliability.

Recycled PET foam core sandwich panels with reinforced hybrid composite facesheets: A sustainable approach for enhanced impact resistance

This research explores the Low-Velocity Impact behavior of thermoplastic composite sandwich panels with 100% recycled Polyethylene Terephthalate (PET) foam sourced from post-consumer plastic water bottles. Being recognized as a reliable technique, hybridization using stainless-steel mesh layers was employed to reinforce the panels’ composite facesheets of sandwich panels accessible for modular housing, cold storage rooms and cargo trucks. Adequate impregnation of the reinforcement metallic mesh layer alongside proper skin-to-core adhesion was accomplished by optimizing a two-phase compression molding method. The effect of hybridization on impact response of sandwich panels with two different PET foam core thicknesses, and stacking sequence were evaluated. It was revealed that reinforcing the impacted surface of the composite sandwich panels significantly increased the perforation threshold. Moreover, analyzing the post-impact section view of the samples indicated that hybridization modified the damage propagation response of the PET foam core sandwich composites, through which the energy absorption capacity was improved.

Study on the Dynamic Crushing Behaviors of Hourglass Honeycomb Sandwich Panels

In response to the problem of enclosed internal spaces in existing honeycomb sandwich panels, the concept of an hourglass honeycomb sandwich panel model is proposed for the first time, which provides a breakthrough approach for achieving the multifunctional integration of honeycomb sandwich panels. Numerical simulation methods are employed to investigate the dynamic performance of the hourglass honeycomb sandwich panels. The focus is on discussing the influences of the geometric parameters on the deformation mode, dynamic response, load uniformity, and energy absorption capacity of the hourglass honeycomb sandwich panel under different impact velocity conditions. The research results indicate that under low-velocity-impact conditions, the influence of the geometric parameters is predominant. In contrast, under high-velocity-impact conditions, the influence of the impact velocity conditions is predominant. Hourglass honeycomb sandwich panels with low density, a large inclination angle of the honeycomb wall, and small contact distances between the hourglass honeycomb cell and the panel have excellent load uniformity, and the distances between the contact points of the hourglass honeycomb cell and the panel have a great influence on the energy absorption capacity of the sandwich panels. This study provides a theoretical basis for the application of honeycombs in aerospace and other engineering areas.

Structural response of steel-concrete composite panels to near field simultaneous blast and fragmentation loading

Steel-concrete composite sandwich panels are used in blast doors or blast walls to protect personnel and equipment in explosive environments due to their superior performance against blast effects. In the design of such panels, most design methods treat blast and fragment loading independently for far-field explosions. However, the synergistic effects of combined blast and fragments loading should be accounted for in close-in explosion scenarios. In this study, a field test program was conducted to assess the damage of the steel-concrete composite panels subjected to close-in explosion of cased charges at various scaled distance between 0.39 and 0.78 m/kg1/3. Characterization test of cased charge detonation was performed to explore the combined loading effect. The analysis includes the pressure-time history from the cased charge detonation, distribution of the fragment masses and velocities over the test panels. The structural damage and response of the composite panels against the combined loading effects was measured. The results indicated that in addition to the damage from the blast wave, the panel was remarkably damaged by the fragment impact. Despite the significant structural damage, the panels maintained its structural integrity after the tests. Additionally, quasi-static load tests were conducted on the panels to quantify their load resistant differences in pristine condition and various damaged conditions due to the explosive effects.

Dynamic response of hemispherical-shell sandwich structures subjected to underwater impulsive loading

In this study, experiments and numerical simulations are designed on aluminum sandwich structures with a hemispherical-shell core layer under underwater impact loading to investigate the dynamic response and energy absorption mechanisms. After the hemispherical-shell sandwich panels are designed and fabricated, they are loaded using an experimental apparatus incorporating fluid–structure interactions. The dynamic response of the sandwich panels is captured using the three-dimensional digital image correlation (3D-DIC) method of high-speed photography, and the energy-absorption mechanisms are analyzed via numerical simulation. This study primarily considers the effects of installation orientation, shock wave impulse and adhesive film on the sandwich panels. The results indicate that the deformation mode and impact resistance of the sandwich panels vary depending on the installation orientation. The displacement at the midpoint of the dry facesheet is linearly related to the shock wave impulse. At non-dimensional impulses exceeding 0.0085, the impact resistance of the forward installation target plate is higher. Additionally, the adhesive film significantly affects the deformation mode of the hemispherical-shell core layer. Its removal slightly increases the proportion of energy absorbed at the core. Quantitative and qualitative analyses of the structure-response-energy relationship are performed on the hemispherical-shell sandwich panels, thus providing guidance for investigations pertaining to the underwater impact resistance of future metal sandwich structures.

What motivates U.S. restaurant customers to choose plant-based meat alternative dishes?

ABSTRACT The purpose of this study is to examine how different consumption values influence consumer intentions to choose a dish featuring plant-based meat alternatives at a restaurant by applying the theory of consumption values. The present study also investigates the mediating role of attitude in the relationships between values and consumer intentions. Responses were collected through the Qualtrics panel service and structural equation modeling was employed to analyze the data. The results, based on a total of 682 usable panel responses, indicate that emotional and epistemic values acted as significant driving forces, directly promoting consumers’ intention. Attitude was aroused by distinctive, functional, emotional, and conditional values and in turn, significantly impacted intention. Furthermore, it was found that attitude fully mediated the relationship between conditional value and intention. The results offer useful implications for restaurants that offer menus with plant-based meat alternatives.

Incomplete ordinal panel responses with initial condition and skew-normal random effect

This paper presents a model for the ordinal categorical panel data with skew-normal random effects, endogenous initial condition, and non ignorable (NI) non monotone missing data. We assumed three separate models for the initial condition, subsequent responses, and missing procedure. The baseline or initial response variable and subsequent response variables are modeled as ordinal logistic, whereas the logistic binary model is considered for the missing process where the maximum likelihood estimates are obtained using Monte Carlo methods. The results show that in the presence of missing data, the skew-normal random effects produce better results compared to the normal one, and considering the endogenous initial conditions is effective in modeling the results of the observed and missing responses such that the patients whose severity of schizophrenia is higher at the beginning of the process have a higher chance of missing on the subsequence times. In this research, schizophrenia data and then simulation studies have been used to check the performance of the proposed model. The results show that the skew-normal random effect using the NI non monotone missing mechanism by increasing the skewness value produces better results in the analysis of simulation studies.

The asymptotic-numerical method for the post-buckling response of curvilinearly stiffened panels

Abstract In the present work, the asymptotic-numerical method is applied in conjunction with the Ritz method as a powerful mean for analysing the post-buckling response of panels with variable stiffness skin and curvilinear stringers. Main advantage of the proposed approach is the reduced computational time. The Ritz method guarantees an excellent ratio between accuracy and required degrees of freedom; the asymptotic-numerical method requires just one matrix inversion throughout the solution process. Moreover, the complete analytical representation of the non-linear equilibrium path is obtained, as opposed to the point-by-point representation of predictor-corrector algorithms. Several test cases are presented and compared with standard Newton-Raphson computations and commercial finite element simulations. The results show noticeable saving of computational time. For the test cases investigated, the asymptotic-numerical method requires about one third of the time required by a standard Newton-Raphson routine. These results demonstrate that the combination between Ritz and the asymptotic-numerical method is an excellent strategy for investigating the post-buckling response of innovative curvilinearly stiffened panels.

Experimental validation of vibration similitude laws for stiffened panels excited by a turbulent boundary layer

Stiffened structures excited by a turbulent boundary layer (TBL) occur in many engineering applications, particularly in the aerospace and naval sectors. The structures encountered in these applications are generally large and complex, and carrying out experiments in order to characterize their vibration response can be costly, time-consuming and difficult. To overcome these constraints, the similitude theory can be used to estimate the response of a full scale structure from the response of a reduced scale structure. A simplifying step to determine these similitude laws for stiffened panels consists in modeling the panel as an equivalent orthotropic panel. Then, using the governing equation of the orthotropic panel and considering the TBL excitation, the vibration similitude laws are derived implying similitude conditions to be respected on geometrical and material properties of the structure as well as flow velocity. In this paper, we present the developments of these similitude laws and an experimental validation for panels in air. The similitude conditions are discussed to adequately choose the properties of scaled stiffened panels. Experimental results are presented to show that the structural response of the reference panel can be recovered from the response of the reduced scale panel using the related scaling laws.

Estimating direction of arrival in reverberant environments for wake-word detection using a single structural vibration sensora).

The vibrational response of an elastic panel to incident acoustic waves is determined by the direction-of-arrival (DOA) of the waves relative to the spatial structure of the panel's bending modes. By monitoring the relative modal excitations of a panel immersed in a sound field, the DOA of the source may be inferred. In reverberant environments, early acoustic reflections and the late diffuse acoustic field may obscure the DOA of incoming sound waves. Panel microphones may be especially susceptible to the effects of reverberation due to their large surface areas and long-decaying impulse responses. An investigation into the effect of reverberation on the accuracy of DOA estimation with panel microphones was made by recording wake-word utterances in eight spaces with reverberation times (RT60s) ranging from 0.27 to 3.00 s. The responses were used to train neural networks to estimate the DOA. Within ±5°, DOA estimation reliability was measured at 95.00% in the least reverberant space, decreasing to 78.33% in the most reverberant space, suggesting an inverse relationship between RT60 and DOA accuracy. Experimental results suggest that a system for estimating DOA with panel microphones can generalize to new acoustic environments by cross-training the system with data from multiple spaces with different RT60s.

Infection control nursing competency model for nurses in intensive care units: A Delphi study

Intensive care unit (ICU) nurses require advanced expertise and skills in critical care and need infection control nursing competency (ICNC). Given the lack of research on it, this study aimed to develop a model of ICU nurses' ICNC. A Delphi panel consisting of experts in intensive care nursing and infection control was organized to provide discerning and professional perspective on ICNC. Approved by the Institutional Review Board, a 3-round Delphi survey was conducted via email from July to December 2023. The content validity ratio and the coefficient of variation were calculated for panel responses. Among 17, 15 nurses (88.2%) participated and completed the surveys. About80% were female, and the panel had an average working experience of 14.2years specifically in theICUs or infection control departments at hospitals. After the initial round, a preliminary model was developed, consisting of 10 main components and 59 subelements. After eliminating 5 elements with content validity ratio values below 0.49 in the second survey, the final model, consisting of 10 main components and 54 subelements, was confirmed in the third survey. ICU nurses' ICNC can be understood based on this study's results, and further research can be designed to improve this competency.

Fatigue and Ultimate Strength Evaluation of GFRP-Reinforced, Laterally-Restrained, Full-Depth Precast Deck Panels with Developed UHPFRC-Filled Transverse Closure Strips

A depth precast deck panel (FDDP) is one element of the prefabricated bridge element and systems (PBES) that allows for quick un-shored assembly of the bridge deck on-site as part of the accelerated bridge construction (ABC) technology. This paper investigates the structural response of full-depth precast deck panels (FDDPs) constructed with new construction materials and connection details. FDDP is cast with normal strength concrete (NSC) and reinforced with high modulus (HM) glass fiber reinforced polymer (GFRP) ribbed bars. The panel-to-girder V-shape connections use the shear pockets to accommodate the clustering of the shear connectors. A novel transverse connection between panels has been developed, featuring three distinct female-to-female joint configurations, each with 175-mm projected GFRP bars extending from the FDDP into the closure strip, complemented by a female vertical shear key and filled with cementitious materials. The ultra-high performance fiber reinforced concrete (UHPFRC) was selectively used to joint-fill the 200-mm transverse joint between adjacent precast panels and the shear pockets connecting the panels to the supporting girders to ensure full shear interaction. Two actual-size FDDP specimens for each type of the three developed joints were erected to perform fatigue tests under the footprint of the Canadian Highway Bridge Design Code (CHBDC) truck wheel loading. The FDDP had a 200-mm thickness, 2500-mm width, and 2400-mm length in traffic direction; the rest was over braced steel twin girders. Two types of fatigue test were performed: incremental variable amplitude fatigue (VAF) loading and constant amplitude fatigue (CAF) loading, followed by monotonically loading the slab ultimate-to-collapse. It was observed that fatigue test results showed that the ultimate capacity of the slab under VAF loading or after 4 million cycles of CAF exceeded the factored design wheel load specified in the CHBDC. Also, the punching shear failure mode was dominant in all the tested FDDP specimens.

Numerical and experimental blast response of multilayer laminated glass panels

Laminated glass is used in high-security buildings to mitigate the effects of blasts and ballistic loadings. The multi-layered composition of the laminated glass (LG) panels allows the glass panes to crack and undergo large deflections while preventing glass shards from spalling by mostly remaining attached to the polymeric interlayer. To characterize multilayer LG panels under blast loading, it is essential to develop their static resistance response under uniform loading. A full-scale water chamber was used to experimentally evaluate the quasistatic response to the failure of the multilayer LG panel systems under uniform pressure. The influence of different polymeric interlayer types on the response of multilayer LG panels was studied. Also, the glass breakage patterns and deflections exhibited by various multilayer glass configurations were investigated. The response of LG panels under blast was developed using ANSYS AUTODYN, which was verified using field experiments. LG panels with an Ethylene Vinyl Acetate (EVA) polymeric interlayer experienced the most dynamic deflections, whereas LG panels with an ionoplast SentryGlas® (SG) polymeric interlayer displayed the least dynamic deflections. The results indicated that multilayer LG systems provide higher blast resistance compared to double-layer systems; the additional layers can help reduce glass breakage and maintain structural integrity. Multilayer LG system’s SG interlayer enhanced blast protection by allowing load transfer and ensuring uniform load distribution between glass layers.

Low-velocity impact response and damage mechanism of cosine function cell-based lattice core sandwich panels

This study aims to investigate the impact response and damage mechanism of cosine-function cell-based (CFCB) lattice core sandwich panels. Several low-velocity impact tests were conducted to explore their advantages in impact resistance by comparing them with traditional body-centered cubic (BCC) lattice-core sandwich panels. The impact response and deformation patterns of CFCB lattice core sandwich panels with two different faceplate materials (aluminum alloy and carbon fiber reinforced plastic composite) were experimentally investigated. The CFCB lattice core sandwich panels exhibited higher impact resistance and energy absorption capacity than their BCC lattice core counterparts. Furthermore, sandwich panels with aluminum alloy faceplates provided better impact resistance capacity than those with CFRP faceplates. Subsequently, several numerical models were developed to explore the deformation mechanisms and energy absorption characteristics of CFCB lattice core sandwich panels. In addition, the effects of the core structural parameters on mechanical performance were numerically investigated. Results indicated that increasing the cell rod diameter and/or reducing the cosine period length could decrease the indentation depth and enhance crush force efficiency. Finally, based on the principle of minimum potential energy, a theoretical model was developed to predict the initial peak load of CFCB lattice core sandwich panels with isotropic faceplates. This study aimed to explore the impact response and provide design guidance for CFCB lattice core sandwich panels.

Dynamic response of composite honeycomb sandwich panels subjected to strong dynamic loading

In this paper, composite honeycomb cores were firstly fabricated using a novel hot-press molding method. Under the simulated strong dynamic loading via from foam projectile impact, the dynamic response of composite honeycomb sandwich panels, including deflection, velocity and strain, was obtained by using high-speed camera and three-dimensional digital image correlation (3D-DIC) technology. Then, the damage/failure modes of composite honeycomb sandwich panels were analyzed using scanning electron microscopy (SEM) and ultrasonic C-scan. The results showed that under low impulse impact, panels deformed elastically and mainly suffered delamination damage. The dynamic response was divided into four stages: acceleration, inertia, rebound, and vibration. Under high impulse impact, panels were penetrated. Fiber breakage and matrix cracking were the main failure modes. The dynamic response was divided into four stages: acceleration, inertia, crack generation and cracking. Finally, a progressive damage model based on the strain-based damage criterion of composite fabric and Yeh delamination damage criterion was applied in ABAQUS/Explicit. On this basis, the relation between the honeycomb structure parameters and impact resistance was discussed in detail. Increasing the core height and relative density resulted in reducing the maximum deflection of the back face sheet and attenuating the shock wave. Experimental results and numerical models are of great significance for guiding the design of honeycomb sandwich panels and improving the impact resistance.

Impact of genomic background and developmental state on signaling pathways and response to therapy in glioblastoma patient-derived cells.

Glioblastoma (GBM) tumors represents diverse genomic epigenomic, and transcriptional landscapes, with significant intratumoral heterogeneity that challenges standard of care treatments involving radiation (RT) and the DNA-alkylating agent temozolomide (TMZ). In this study, we employed targeted proteomics to assess the response of a genomically-diverse panel of GBM patient-derived cancer stem cells (CSCs) to astrocytic differentiation, growth factor withdrawal and traditional high fetal bovine serum culture. Our findings revealed a complex crosstalk and co-activation of key oncogenic signaling in CSCs and diverse patterns of response to these external stimuli. Using RNA sequencing and DNA methylation, we observed common adaptations in response to astrocytic differentiation of CSCs across genomically distinct models, including BMP-Smad pathway activation, reduced cholesterol biosynthesis, and upregulation of extracellular matrix components. Notably, we observed that these differentiated CSC progenies retained a subset of stemness genes and the activation of cell survival pathways. We also examined the impact of differentiation state and genomic background on GBM cell sensitivity and transcriptional response to TMZ and RT. Differentiation of CSCs increased resistance to TMZ but not to RT. While transcriptional responses to these treatments were predominantly regulated by p53 in wild-type p53 GBM cells, its transcriptional activity was modulated by the differentiation status and treatment modality. Both mutant and wild-type p53 models exhibited significant activation of a DNA-damage associated interferon response in CSCs and differentiated cells, suggesting this pathway may play a wider role in GBM response to TMZ and RT. Our integrative analysis of the impact of GBM cell developmental states, in the context of genomic and molecular diversity of patient-derived models, provides valuable insights for pre-clinical studies aimed at optimizing treatment strategies.

Triaxial compressive behaviour of ultra-high performance geopolymer concrete (UHPGC) and its applications in contact explosion and projectile impact analysis

Ultra-high performance geopolymer concrete (UHPGC) is increasingly recognised as a promising construction material in protective engineering owing to its exceptional material strength and eco-friendly characteristics. However, there is currently limited research data on the behaviour of UHPGC under complex stress states, and the applicability of some common concrete dynamic constitutive models to UHPGC requires calibration and evaluation. This paper presents an experimental study on the triaxial compression (TXC) behaviour of UHPGC under varying confining pressures with a range of 0–40 MPa. The stress-strain curves under various confinement levels and failure patterns of UHPGC are discussed. The results indicate that the peak axial stress and toughness of UHPGC increase with higher confining pressure levels, but it still exhibits noticeable softening behaviour. Under uniaxial compression, UHPGC typically fails with inclined shear and axial tensile cracks, while under TXC, particularly at confining pressures above 20 MPa, the failure mode transitions to shear failure with prominent oblique shear cracks. Additionally, existing failure criteria are calibrated to match the strength envelop of UHPGC, with the Power-law failure criterion providing the closest fitting results. Subsequently, utilising both current and pre-existing TXC data, three commonly used concrete constitutive models, including HJC, K&C and CSC, are calibrated with respect to the dominant strength parameters for UHPGC in the finite element (FE) hydrocode ANSYS/LS-DYNA. Further, numerical simulations are conducted to evaluate the effectiveness of such three calibrated concrete models in replicating the response of UHPGC panels exposed to the contact explosion or projectile impact. The simulation results demonstrate that the K&C and CSC models effectively replicate the localised damage of UHPGC panels under contact explosions, while the HJC model more accurately simulates the depth of penetration (DOP) for thick UHPGC panels under projectile impact.

Dynamics for rigid–flexible coupled solar panel multibody system composed of composite laminated plates

Composite laminates are widely employed in the fabrication of solar panels in modern spacecraft engineering because of their superior durability, mechanical qualities, and cost-effectiveness. This research is dedicated to multibody system dynamics modeling of composite laminate solar panels, specifically the coupling system between the rigid main body and the flexible solar panels. In this study, the rigid body is modeled using the natural coordinate formulation (NCF), and for the flexible solar panel, the absolute nodal coordinate formulation (ANCF) with a 36-DOF reduced-order composite thin shell element is used to accurately capture the coupling effect of the solar panel under large motion and deformation. Compared to a 48-DOF fully parameterized thick plate element, this method efficiently avoids shear locking and improves numerical solution convergence efficiency. Based on the Kirchhoff theory and the constitutive relationship of composite laminates, a dynamic model of the multibody system is developed, taking into account the rigid-flexible coupling effect and the kinematic constraints. This work thoroughly discusses the dynamic behavior of solar panel deployment using a comparative analysis of numerical simulation and virtual prototype simulation, and the accuracy is verified. The findings indicate that the flexible characteristics and fiber orientation of composite laminates have a significant impact on the dynamic response of solar panels during deployment. Furthermore, the bang-bang attitude controller is designed, and the difference in dynamic response between the two modeling methods in controlled and uncontrolled states is studied, providing an important theoretical foundation and technical support for solar panel design and analysis.

Response of circular type sandwich panel using JUCO-glass fiber with PU foam under three-point bending loading

In this study, a circular type honeycomb sandwich panel using natural JUCO and synthetic woven glass fiber was fabricated, and the bending properties like bending strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were evaluated. Polyurethane (PU) foam was injected into the core structure to improve the bending strength. The orientation of jute and cotton fiber was varied to investigate the best stiffness and strength. In addition, twill-type JUCO fiber mat and synthetic woven glass fiber were also used to fabricate the circular type honeycomb sandwich panel. Finite element modeling was undertaken to validate the experimental results. Prior to the finite element analysis, a tensile test was carried out to determine the boundary conditions. Injecting polyurethane foam into the honeycomb core does not show any significant impact on bending properties. However, the deformation rate increased considerably by adding PU foam in the core structure. According to the results, honeycomb sandwich panels made of woven glass fiber with PU foam exhibited more homogenous deflection and bending compliance compared with others.

Global buckling response of sandwich panels with additively manufactured lattice cores

This paper deals with the analytical and numerical global buckling analysis of rectangular sandwich plates utilized AlSi10 Mg in both facesheets and lattice cores. In this study, six different strut-based lattice core models are designed. Additionally, the buckling resistance of lattice panels is compared with a typical honeycomb panel. Analytical studies were carried out using Kirchoff plate theory (CLPT), first-order shear deformation theory (FSDT) coded on MATLAB and finite element (FE) analyses in Abaqus. In the theoretical approaches, the Navier solution is derived for sandwich plates with simply supported boundary conditions at all edges. In the FE analyses, validated homogenized lattice structures models were used to avoid excessive numbers of elements and to save computational time. The parametric effects of side-to-thickness ratio, and different designed core cells on global buckling responses are investigated. As a result of comparing the analytical results with the FE model, a good agreement is obtained, and it is found that analytical buckling analyses FSDT can be used within certain size limits for the global buckling analysis of lattice core sandwich structures.