Ply Orientation Angles Research Articles

Role of intra-lamellar collagen and hyaluronan nanostructures in annulus fibrosus on lumbar spine biomechanics: insights from molecular mechanics-finite element-based multiscale analyses.

Annulus fibrosus' (AF) ability to transmit multi-directional spinal motion is contributed by a combination of chemical interactions among biomolecular constituents-collagen type I (COL-I), collagen type II (COL-II), and proteoglycans (aggrecan and hyaluronan)-and mechanical interactions at multiple length scales. However, the mechanistic role of such interactions on spinal motion is unclear. The present work employs a molecular mechanics-finite element (FE) multiscale approach to investigate the mechanistic role of molecular-scale collagen and hyaluronan nanostructures in AF, on spinal motion. For this, an FE model of the lumbar segment is developed wherein a multiscale model of AF collagen fiber, developed from COL-I, COL-II, and hyaluronan using the molecular dynamics-cohesive finite element multiscale method, is incorporated. Analyses show AF collagen fibers primarily contribute to axial rotation (AR) motion, owing to angle-ply orientation. Maximum fiber strain values of 2.45% in AR, observed at the outer annulus, are 25% lower than the reported values. This indicates native collagen fibers are softer, attributed to the softer non-fibrillar matrix and higher interfibrillar sliding. Additionally, elastic zone stiffness of 8.61 Nm/° is observed to be 20% higher than the reported range, suggesting native AF lamellae exhibit lower stiffness, resulting from inter-collagen fiber bundle sliding. The presented study has further implications towards the hierarchy-driven designing of AF-substitute materials.

Free vibration analysis of multi-layer perforated fibre-reinforcement damping composite beam

This paper investigates the effective elastic constants of the perforated fibre-reinforcement damping membrane, taking into account the variations in perforation array and ply orientation angle using the homogenization method and the off-axis stress-strain relation. The equations for the free vibration of the composite beam with multi-layer perforated fibre-reinforcement damping membranes are derived using the first-order shear deformation theory and the Hamilton principle. These equations are then solved using the Navier method. The novelty of this paper lies in the achievement of an effective elastic constants model and vibration analysis for the multi-layer composite beam under simply supported boundary conditions. The calculated results are then compared with experimental values and finite element results to validate the theoretical model and method. Furthermore, the paper explores the graphical variation of mechanical performance with system parameters, providing a theoretical foundation for future researchers in the composite field.

Maximum buckling load design and post-buckling compressive failure of curved grid sub-stiffened composite panels

The structural efficiency of composite stiffened panels can be substantially improved by utilizing curved stiffening components due to their exceptional mechanical performance and design flexibility. This paper aims to explore the impressive potential offered by the curved stiffening concept in the design of T-shaped stiffened composite panels featuring curved sub-stiffening components. An optimization design framework is proposed to optimize the laminates sequence of skin, ply orientation angles and distribution of the curved sub-stiffeners as well as the curvature of the sub-stiffeners of the proposed curved grid sub-stiffened composite panels to yield higher buckling performance without additional weight. Results demonstrate that introducing composite curved grid sub-stiffeners to the T-shaped stiffened composite panel leads to substantial improvements (+254.42%) in buckling performance, while maintaining equivalent weight designs. Furthermore, the introduction of composite curved grid sub-stiffeners reveals alterations to the post-buckling deformation paths of grid sub-stiffened composite panels, leading to varied collapse loads and degrees of deformation in the composite panels. This highlights the importance of utilizing the composite curved grid sub-stiffeners to improve stability and reduce the risk of failure in thin-walled structures, all while meeting lightweight design criteria.

Vibration assessment of dual core sandwich beam with a biomimetic lamellar honeycomb core and MWCNT reinforced facesheets

The usage of sandwich structures has been increasing in the field of defense, transportation, and aerospace applications due to the many advantages like, thickness to mass ratio, high bending stiffness, and strength. In this present work, the vibration assessment of the dual-core sandwich beam with biomimetic core and multiwalled carbon nanotube (MWCNT) reinforced composite face layers has been performed. The lamellar honeycomb (LHC) core is a biomimetic design developed here from the pistachio shell structure and manufactured by 3D printing process. The mechanical characteristics of biomimetic core are measured using an alternative dynamic technique and impulse excitation test was used to assess the material properties of MWCNT composite laminates. Using finite element software, a numerical model is created for a composite dual-core sandwich beam containing MWCNTs and a biomimetic core. The developed numerical model is validated with experimental and available literature results in terms of natural frequencies and it shows good agreements. Additionally, parametric studies are performed to investigate the natural frequencies of MWCNT composite dual-core sandwich beam with biomimetic cores for ply orientation angles, aspect ratio, and support conditions. The MWCNT reinforcement in the facesheets and LHC core enhances the structural performance and stiffness of the laminated composite dual-core sandwich beam. This research will provide the valuable insights to engineers and scientists for the construction of large capacity ships and race boat structures.

Investigating the Out-of-Plane Bending Stiffness Properties in Hybrid Species Diagonal-Cross-Laminated Timber Panels

Since the introduction of Cross-laminated Timber (CLT) in Austria in the early 1990s, the adoption of this 90°-crosswise-laminated product has seen exponential growth worldwide. Compared to traditional laminated timber products (e.g., glulam), CLT provides improved dimensional stability but with reduced out-of-plane bending stiffness. To improve the bending stiffness, while maintaining relative dimensional stability, a modified orientation of the inner layers in a diagonal direction can be used. This novel product is Diagonal-Cross-laminated Timber (DCLT), a composite timber product, consisting of inner layers which are rotated at different angle-ply orientations between 0 and 90 degrees to the outer layers. To properly model the out-of-plane bending behavior of the DCLT, analytical models and finite element analysis (FEA) were used, and the results were validated by four-point bending tests performed on DCLT panels with angle-ply orientations of 10°, 20°, 40°, 70°, and a conventional CLT 90° panel. The results indicate that DCLT panels with angle-ply cross layers have a structural advantage in out-of-plane bending over traditional CLT (90°) panels. The apparent bending stiffness from DCLT 90° to DCLT ± 10° has an increase of 33%, 24%, and 35%, respectively, regarding the assessed methods of experimental, theoretical, and FEM modeling. Using these panels would allow for increased spans or load-carrying capacity for a given panel span-to-depth ratio. The development of DCLT and its introduction to the industry not only could enable the use of lower-quality timber that would not otherwise satisfy structural requirements for CLT but also could help reduce the fabrication cost of CLT due to utilizing lower amounts of fiber.

Aeroelastic tailoring of stiffened cantilever plate using composites and structural layouts: A parametric study

AbstractThis paper studies the aeroelasticity of a stiffened cantilever plate using composite material and novel structural layouts. A comprehensive parametric study is conducted to determine the influence of different design parameters on the aeroelastic boundaries. Design parameters include plate sweep angle, ply orientation, stringer cross-section and stringer sweep angle. Nastran is used to run the aeroelastic analysis, and the process is automated using ${\rm{Matla}}{{\rm{b}}^{}}$ . The structure of the plate is modelled using laminate elements whereas the stringers are modelled using the Euler-Bernoulli beam elements. The unsteady aerodynamic loads are modelled using doublet-lattice method (DLM) and the structural and aerodynamic meshes are connected using an infinite plate surface (IPS) spline. A mesh sensitivity analysis is conducted to ensure fine meshes for the aerodynamics and structure. The study’s findings demonstrate the benefits of employing forward swept (Fw) stringers since it increases flutter speed by almost 38% compared to the unswept stringers case and prevents divergence. Moreover, the static aeroelastic analysis illustrates that the utilisation of Fw swept stringers can reduce the average tip displacement and tip twist effectively. T-shaped stringers are recommended to stiffen the plate due to their lower impact on the total mass of the plate. In some configurations, the structural layout has a much higher effect on the aeroelastic instabilities when compared to the material effect (ply orientation). However, results suggest combining both for some cases to get balanced washin and washout effects.

A Microscale Analysis of Thermal Residual Stresses in Composites with Different Ply Orientations.

Composites, such as fiber-reinforced plastics, are produced using layering prepregs with varying ply orientations to achieve enhanced mechanical properties. However, this results in intricate residual stresses, which are influenced by the forming process and ply orientation. In this study, three representative microscopic models-featuring discrete fiber and resin-represent unidirectional, cross-ply, and angle-ply laminates. These models underwent simulations under three different cooling histories using the finite element method. The findings suggest that ply orientation does not significantly influence temperature distribution. However, it significantly impacts the von Mises stress in the fiber closest to the interface between two stacked laminae. This differs from the inter-laminar stresses determined with the macroscopic lamination model. Apart from the free edge, which exhibits a complex stress distribution, the von Mises stress within a unit cell displays a recurring pattern. The magnitude of the von Mises stress decreases as the ply orientation angle increases and shifts when a temperature gradient is present throughout the composite's thickness. This study provides valuable insights into the mechanics of residual stresses at the microscopic level and highlights potential defect areas influenced by these stresses.

Free vibration analysis of the sandwich structured composite annular plates: Numerical and experimental investigation

Sandwich structures are interesting structural elements due to their high stiffness-to-weight ratio, high fatigue resistance, and excellent vibration characteristics. The aerospace industry relies heavily on these types of structures considering the different optimized materials and shapes available for sandwich construction. In the present study, vibration aspects of annular sandwich structures with composite laminates and a 3D printed honeycomb core are investigated in both the numerical and experimental methods. Amongst the various shapes of sandwich structures, annular sector plates are predominantly used in the construction of modern bridges, aircrafts, and automobile parts. Furthermore, the investigation of annular sandwich plates featuring GFRP facesheet and 3D printed PLA cores are studied in a very limited extent. In order to obtain the sector plates experimentally, Glass Fiber Reinforced Polymer (GFRP) laminates are fabricated by hand layup techniques, and the 3D printing Poly-lactic Acid (PLA) honeycomb core is manufactured using Fused Deposition Modelling (FDM). The material properties of honeycomb core and composite skins are estimated with the help of Gibson formulation and rule of mixture, respectively. Based on available literature, the analysis approach is validated through numerical analysis using ANSYS Finite Element (FE) software. Also, the frequency responses of annular sandwich plate were measured in both experimental and numerical analysis and the results showed good agreement. However, in order to describe the effectiveness of annular composite sandwich plates, parametric studies are carried out in terms of natural frequencies and mode shapes with different configurations of core geometry, ply orientation, boundary constraints, and inner to outer radius ratio. The research outcome highlights that the optimum angle ply orientation, core height of 12.5 mm with clamped–clamped condition and inner to outer radius of 0.75 mm yields better structural stiffness.

Buckling optimization and post-buckling analysis of omega sub-stiffened composite panels using different cohesive interface properties

This paper investigates the effect of a new sub-structural configuration (omega sub-stiffener) on the buckling and post-buckling performance of an existing T-stiffened composite panel design. An optimization framework is proposed to optimize the distribution of omega sub-stiffeners, the laminate stacking sequences, and the ply orientation angles of omega sub-stiffened composite panels to yield higher initial buckling performance without adding mass. Further, different stiffener-panel cohesive interface properties are considered to analyze the underlying mechanism of omega sub-stiffeners involved in the panel’s post-buckling deformation paths and ultimate failure load during the compressive post-buckling process. Results show that introducing omega sub-stiffeners into the T-stiffened composite panel can result in an increased initial buckling performance (+242.63%) and causes re-establishment of the concentrated stress region, which yields different degrees of deformation and collapse in composite panels, and alters the failure behavior and further affects the initiation and propagation of various failure modes.

Cellulose nanocrystal-assisted processing of nanocomposite filaments for fused filament fabrication

This study introduces a scalable processing technique where cellulose nanocrystals (CNCs) are used to integrate pristine multi-walled carbon nanotubes (CNTs) into acrylonitrile butadiene styrene (ABS) polymer without functionalization, solvents, or surfactants. A synergy between the nanomaterials and printed road angle was discovered, with angle ply orientation optimizing mechanical properties and longitudinal orientation improving thermal conductivity. Mechanical properties improved up to 81% in tensile strength and 95% in elastic modulus, while a 102% increase in interlaminar strength was exhibited. The thermal conductivity trend showed an anisotropy between radial and axial directions, where one could be increased while the other was diminished, with as much as 807% increase in the transverse sample. By optimizing print orientation and nanoparticle content, tailored material properties are achievable.

Three-point bending characteristics of all-composite sandwich panels with different core configurations

With cores of the hexagonal honeycomb (HH), staggered corrugated lattice (SCL), bidirectional corrugated lattice (BCL), reinforced hexagonal honeycomb (RHH), and reinforced staggered corrugated lattice (RSCL) made by cutting, bonding, arranging and weaving the trapezoidal corrugation (TC) formed by mold hot pressing, six types of composite sandwich panels of the same macro size were proposed. The failure processes of the six sandwich panels in three-point bending experiments were compared and analyzed, and the effects of core configuration and reinforced stiffener on the bending response were evaluated. A general analytical model was established to predict the bending stiffness and failure mode of six sandwich panels, which was also visually presented by a three-dimensional numerical model. The numerical and experimental results validated the effectiveness of the analytical model. The effects of ply parameters and corrugated sizes on bending responses were studied by a combing application of experiment, analytical and numerical models. The three-dimensional failure mechanism maps were displayed to evaluate the failure mode and failure load. The longitudinal discontinuity of the bonding zone of the core could significantly weaken the bending performance and bonding strength of BCL, SCL, RSCL, and HH. The peak load of SCL and HH was enhanced by 45.97% and 60.29%, respectively, by setting stiffeners. Both RHH and TC could achieve bending stiffness of more than 3.5 kN·mm−1, while the failure load of the latter could be up to 25 kN. The design parameter space of bending stiffness, failure load with respect to ply orientation angle, core wall thickness, corrugated web angle, and horizontal segment length was provided intuitively.

Bending responses of CFRP thin-walled tubes with different sectional shapes: Experimental, analytical and numerical investigation

The stiffness, elastic ultimate load and failure mode of carbon fiber reinforced plastic (CFRP) thin-walled square tube (ST), chamfered square tube (CST) and circular tube (CT) with the same circumference under transverse bending load were compared and analyzed. The load-displacement curves, strain-time curves and video images were recorded throughout the process of quasi-static bending to capture the initiation and propagation of failure. Based on the shear-deformable beam and planar curved rod deformation theory, the analytical models for evaluating the integral stiffness and local stiffness of CFRP thin-walled tube were established respectively. The failure mechanisms of ST, CST and CT were further revealed by developing finite element model. The effects of boundary condition, ply orientation angle, geometric dimension and indenter shape on bending properties of CFRP thin-walled tubes were studied. According to the failure characteristics of CST and CT, the indenters that can increase the contact zone were designed and tested. The complete failure of ST was caused by split cracks extending and web buckling, while that of CT was malposed cracks spreading and wall collapsing. The local stiffness of ST and the integral stiffness of CT were the optimum among three specimens. The elastic ultimate load of CST and CT could be improved by adopting 45° layers and the designed indenters. The boundary condition correction coefficient was calculated and fitted utilizing numerical total stiffness and analytical integral stiffness, contributing to explore the ply orientation angle and geometric dimension design space of CST stiffness parameters.

Sparse Polynomial Chaos Expansion for Uncertainty Quantification of Composite Cylindrical Shell with Geometrical and Material Uncertainty

The geometrical dimensions and mechanical properties of composite materials exhibit inherent variation and uncertainty in practical engineering. Uncertainties in geometrical dimensions and mechanical properties propagate to the structural performance of composite cylindrical shells under hydrostatic pressure. However, traditional methods for quantification of uncertainty, such as Monte Carlo simulation and the response surface method, are either time consuming with low convergence rates or unable to deal with high-dimensional problems. In this study, the quantification of the high-dimensional uncertainty of the critical buckling pressure of a composite cylindrical shell with geometrical and material uncertainties was investigated by means of sparse polynomial chaos expansion (PCE). With limited design samples, sparse PCE was built and validated for predictive accuracy. Statistical moments (mean and standard deviation) and global sensitivity analysis results were obtained based on the sparse PCE. The mean and standard deviation of critical buckling pressure were 3.5777 MPa and 0.3149 MPa, with a coefficient of variation of 8.801%. Global sensitivity analysis results from Sobol’ indices and the Morris method showed that the uncertainty of longitudinal modulus has a massive influence on the critical buckling pressure of composite cylindrical shell, whereas the uncertainties of transverse modulus, shear modulus, and Poisson’s ratio have a weak influence. When the coefficient of variation of ply thickness and orientation angle does not surpass 2%, the uncertainties of ply thickness and orientation angle have a weak influence on the critical buckling pressure. The study shows that the sparse PCE is effective at resolving the problem of high-dimensional uncertainty quantification of composite cylindrical shell with geometrical and material uncertainty.

Optimal design of vibro-impact resistant fiber reinforced composite plates with polyurea coating

This paper studies on optimal design of vibro-impact resistant fiber reinforced composite plates (FRCPs) with polyurea coating. Initially, a theoretical model for the coated FRCP structures under elastic boundary conditions is proposed, through which dynamic stiffness and impact damage area are predicted. Here, based on the first-order shear deformation theory and the Rayleigh-Ritz method, the dynamic stiffness of coated FRCP structures is calculated, which is taken as an index of vibration suppression performance. Regarded as an index of anti-vibration performance, the impact damage area is identified by employing the Hertz contact law and the predefined delamination threshold load. After validation of the proposed model against a series of experiments on coated and uncoated FRCP specimens, optimization analysis is then conducted based on the Non-dominated Sorting Genetic Algorithm, where the maximum dynamic stiffness, the minimum impact damage area and structural mass are defined as objective functions, and thickness ratio, elastic modulus ratio and ply orientation angle are taken as design variables. It has been found that to possess the desired vibration and impact resistant capabilities together with maintaining lightweight property, it is recommended to choose design variables associated with the turning point of Pareto-optimal solutions as the final optimal results.

Buckling response of laminated FG-CNT reinforced composite plates: Analytical and finite element approach

A 3D finite element model using suitable user subroutines in ABAQUS finite element software and an analytical solution based on the third-order shear deformation laminated plate theory combined with von Kármán's geometric nonlinearity are proposed to simulate the functionally graded Carbon Nanotubes (CNTs) throughout a plate's thickness. The former is used for the estimation of the buckling response and the latter is used for the estimation of both buckling and post-buckling response of laminated nanocomposite plates under uniform and parabolic loading. In the analytical approach, the governing equations are solved by the Galerkin method and Airy's stress function to obtain the buckling coefficient of FG-CNT reinforced composite plates. The effect of various factors, such as boundary conditions, types of loads, distribution type and volume fraction of CNTs, geometrical parameters, etc on the buckling and post-buckling response is investigated. It has been found that a higher volume fraction of CNTs increases the buckling and post-buckling strength of laminated composite plates, whereas the laminated plate with angle-ply orientations equal to 45 degrees has the maximum buckling load factor among the CNT fiber orientations considered.

Comparative Analysis of Hole Surface Quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate With 90°/0°/90° Ply Orientation Angle

Comparative Analysis of Hole Surface Quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate With 90°/0°/90° Ply Orientation Angle

Comparative Analysis of hole surface quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate with 45°/0°/45° Ply Orientation Angle

Comparative Analysis of hole surface quality in CNC Drilling of Novel Sisal Fibre Reinforced Aluminium Wire Mesh Sandwich Composite and Sisal Fiber Laminate with 45°/0°/45° Ply Orientation Angle

Comparative Analysis of Delamination Factor in CNC Drilling of Novel Kenaf Fiber Reinforced Aluminum Wire Mesh Sandwich Composite and Kenaf Fiber Laminate with 45o /0o /45o Ply Orientation Angle

Comparative Analysis of Delamination Factor in CNC Drilling of Novel Kenaf Fiber Reinforced Aluminum Wire Mesh Sandwich Composite and Kenaf Fiber Laminate with 45o /0o /45o Ply Orientation Angle

Effect of Delamination on Natural Frequencies of E-glass and S-glass Epoxy Composite Plates

The delamination is one of the major modes of failure occurring in the laminated composite due to insufficient bonding between the layers. In this paper, the natural frequencies of delaminated S-glass and E-glass epoxy cantilever composite plates are presented by employing the finite element method (FEM) approach. The rotary inertia and transverse shear deformation are considered in the present study. The effect of parameters such as the location of delamination along the length, across the thickness, the percentage of delamination, and ply-orientation angle on first three natural frequencies of the cantilever plates are presented for S-glass and E-glass epoxy composites. The standard eigenvalue problem is solved to obtain the natural frequencies and corresponding mode shapes. First three mode shape of S-Glass and E-Glass epoxy laminated composites are portrayed corresponding to different ply angle of lamina.

Influence of hole quality on fatigue life of drilled CFRP with the different ply orientation angle

In this study, the effect of drilling quality on fatigue life of UD, 0/90, and ± 45 fiber angle carbon fiber reinforced plastics (CFRP) was investigated. CFRPs were drilled using WC, HSS, and Brad Spur tool types that have different geometries and materials at different feed rates of 0.05, 0.10, and 0.15 mm/rev, and at the different spindle speeds of 1000, 3000 and 5000 rev/min. Thrust forces were measured during the drilling of CFRPs, and surface roughnesses, deformation factors, and maximum tensile forces were measured after drilling operations. Thrust force, surface roughness, and deformation factor were evaluated in terms of drilling quality. The drilling parameters that cause the best, average, and worst drilling quality were determined. Then, fatigue behaviors of CFRPs drilled in these drilling parameters were investigated. Fatigue tests were carried out at %75, %80, %85, and %90 load ratios based on the lowest tensile force of the drilled samples. As a result of the study, it was determined that the thrust force, the deformation factor, and the surface roughness increased as the feed rate increased. However, the thrust force, the deformation factor, and the surface roughness decreased as the spindle speed increased. Besides, the best drilling quality was obtained from the drilling operation performed using WC tool type, at a spindle speed of 5000 rev/min and a feed rate of 0.05 mm/rev. The worst drilling quality was obtained from the drilling operation performed using Brad Spur tool type, at a spindle speed of 1000 rev/min and a feed rate of 0.15 mm/rev. With the decreasing drilling quality, a significant decrease occurred in the tensile force and fatigue life of CFRPs. The tensile load and fatigue life of CFRPs drilled in optimum drilling parameters were obtained higher. In the case of selecting the correct drilling parameters, it was observed that the reduction in fatigue life of CFRPs could be prevented ratios of %22–49.