Cutout Size Research Articles

Buckling Performance Evaluation of Double-Double Laminates with Cutouts Using Artificial Neural Network and Genetic Algorithm

Although the double-double (DD) laminates proposed by Tsai provide a promising option for achieving better structural performance with lower manufacturing and maintenance costs, the buckling performance of perforated DD laminates still remains clear. In this study, optimal ply angles, rotation angles, and the corresponding maximum buckling loads are determined for DD laminates with various cutouts, which are used for comparisons to evaluate the effects of cutout size and shape on the buckling behaviour of perforated DD laminates. Apart from conventional circular and elliptical cutouts, the use of a combined-shape cutout for DD laminates is also investigated. As a large number of optimisations are required to obtain the maximum buckling loads for different cases in this study, an efficient optimisation method for perforated DD laminates is proposed based on an artificial neural network (ANN) and a genetic algorithm (GA). Unlike conventional quadaxial (QUAD) laminates, the repetition of a four-ply sublaminate in DD laminates makes their layup to be represented by only two ply angles; hence, the application of ANN models for predicting the buckling behaviour of various perforated DD laminates is studied in this paper. The superior performance of the ANN models is demonstrated by comparisons with other machine learning models. Instead of using the time-consuming FEA, the developed ANN model is utilised within a GA to obtain the maximum buckling load of perforated DD laminates. Compared to the circular cutout, the use of elliptical and combined-shape cutouts leads to more noticeable changes in the optimal ply angles as the cutout size increases. Based on the obtained results, the use of the combined-shape cutout is recommended for DD laminates.

Investigation of axial buckling behavior in composite laminates reinforced with S-glass fiber and epoxy featuring double cutouts

This research examines the impact of double cutouts on the critical buckling load of woven S-Glass/epoxy composite laminates. The study is divided into two parts: the first part involves comparisons, while the second part introduces numerical analyses. Initially, critical buckling loads of composite laminates without cutouts are determined using numerical and experimental methods. Subsequently, the results are compared to ensure consistency of critical load values obtained from the different methods. In the second part, the study investigates the effects of fiber angle, shape (square and circular), size, and position of cutouts in the composite plate using finite element analysis. The findings suggest that the shape and position of the cutout on the plate primarily influence the critical buckling load of the composite plates with circular cutouts, resulting in a relatively lower change in buckling load compared to square ones.

Effects of Cutouts on Energy Absorption Characteristics of Thin-walled Tube Impacted under Dynamic Loading

A thin-walled tube is an energy absorber device that is commonly used in automotive and locomotive applications. The function of this element is to convert the kinetic energy into other forms of energy during a collision that can minimize injuries to the passengers. Therefore, various studies have been reported previously to improve the thin-walled structure to decrease the damage and provide protection for the vehicle and occupant. This study aims to determine the effects of the cutout on the thin-walled tube when impacted under dynamic axial loading. The effects of sizes, shapes, locations, and the number of cutouts on the energy absorption characteristics have been analyzed by using the validated finite element model. The result indicates that a circular tube with a square cutout shape, larger cutout sizes, and near the top-end of the tube has more energy absorption characteristics. Furthermore, the results of energy absorption (EA), crush force efficiency (CFE), and specific energy absorption (SEA) are highest when applying four cutouts on the surface of the thin-walled tube. Research information provided in this study will serve as a guide in designing the cutout thin-walled tube for crashworthiness enhancements in the future.

Optimizing deployment dynamics of composite tape-spring hinges

The composite tape-spring hinge (CTSH) is a lightweight structural connector widely employed in space structures, including spacecraft and satellites, due to its high specific strength and stiffness. Introducing cutouts enables CTSH to possess folding and deployment capability, while optimizing the cutouts finely to optimize the performance of CTSH. However, the interaction between cutout size and the dynamic deployment of CTSH is a novel topic. To address this, a multi-objective optimization problem is formulated, aiming to minimize both the maximum overshoot angle and deployment time while considering mass constraints. An accelerated size optimization is achieved by integrating data-driven surrogate modeling and size optimization. The optimized CTSH design exhibits a significant improvement in performance, with a 26.3% reduction in the maximum overshoot angle and a 12.6% reduction in the deployment time compared to the initial design. The proposed optimization strategy is highly adaptable and can be applied to various optimization problems, offering valuable insights for future designing space deployable structures with desirable performance.

Investigation of the Usefulness of Monte Carlo Simulation in Electron Beam Therapy Using Body Surface Lead Cutout

The purpose of this study was to understand the PDD and OAR during electron beam therapy using lead cutout on the body surface. The Monte Carlo code PHITS version 3.24 was used to simulate PDD and OAR. The simulation results were compared with actual measurements using a silicon diode detector to evaluate the validity of the simulation results. The simulated PDD and OAR parameters of the linac agreed with the measured values within 2 mm. When the lead cutout on the body surface was used, all parameters except for R100 agreed with the measured values within 2 mm. The cutout sizes of the broad-beam square irradiation fields were 3 cm for 6 MeV, 5 cm for 12 MeV, and 8 cm for 18 MeV when the lead cutout on the body surface was used. The Monte Carlo simulation was useful for understanding the PDD and OAR of the lead cutout irradiation fields, which are difficult to measure.

Natural Frequency Characteristics of Stiffened FG Multilayer Graphene-Reinforced Composite Plate with Circular Cutout Resting on Elastic Foundation

In this research, natural frequency response of functionally-graded multilayer graphene-reinforced composite plate with circular cutout reinforced by orthogonal stiffeners is investigated for the first time. The structure is surrounded by Winkler-type elastic support. The plate is composed of polymethyl methacrylate (PMMA) as matrix material and reinforced by graphene platelets (GPLs). The material of the orthogonal stiffeners is the same as that for the matrix. Rule of mixtures and Halpin–Tsai approach are applied to estimate the effective material properties of the composite plate. Third-order shear deformation plate theory and finite element procedure is employed to obtain the element matrices of the structure. Natural frequencies and mode shapes of the stiffened plate are reported for different variables such as nanofillers dispersion patterns, width and height of the stiffeners, aspect ratio of plate, plate thickness ratio, weight fraction of nanofillers, number of stiffeners, boundary conditions, elastic foundation stiffness parameter and size of circular cutout. The obtained results denote that with the addition of a set of stiffeners, fundamental frequency enhanced up to 32.3% with just about 10% increase of mass.

Free vibration characteristics of integrated fluted-core composite sandwich cylinders

Due to their excellent mechanical properties and inherent design versatility, fluted-core composite sandwich structures have gained substantial attention in aerospace and rail transit applications. This study investigated the free-vibration characteristics of composite fluted-core sandwich cylinders. Theoretical models were established following the Rayleigh-Ritz method to predict the natural frequencies of sandwich cylinders under free vibration. The representative cylindrical specimens were prepared using carbon fiber-reinforced plastics (CFRP) and integrated forming co-cured method. To analyze the additional effects of cutouts on vibration performance, specimens with circular cutouts were also fabricated. The vibration tests were performed to determine the natural frequencies and modal shapes under free-free boundary conditions. Validated finite element simulations were employed to assess the accuracy of theoretical results and investigate the influences of geometric parameters on the structural vibration behavior. The results indicated that circumferential lobar modes characterized the first five mode shapes. Significant enhancements were attained by increasing the structural stiffness through adjustments in the circumferential cell number, core-ribs thickness, or size of cutouts. However, when the structural stiffness increases beyond a certain threshold, it has limited effect on the vibration frequencies. The findings provided a comprehensive understanding of the vibration characteristics and optimized design of fluted-core sandwich cylinders.

Buckling response of functionally graded multilayer graphene platelet-reinforced composite plates with circular/elliptical cutouts supporting on an elastic foundation under normal and shear loads

The present article deals with the buckling response of functionally graded multilayer graphene platelet-reinforced composite (FG-GPL RC) rectangular plates with circular/elliptical cutouts resting on a Winkler-type elastic foundation under uniaxial and biaxial normal and shear loads. Rule of mixtures and the Halpin–Tsai approach are applied to obtain the effective Poisson’s ratio, mass density, and elastic modulus of the reinforced composite. The governing equations are developed by applying the third-order shear deformation plate theory. Then, the finite element procedure is used to solve the problem. Four different types of graphene platelet distributions, namely, UD, FG-X, FG-V, and FG-O, are considered. A broad range of factors such as plate aspect ratio, plate slenderness ratio, applying uniaxial and biaxial normal and shear loads to the plate, several Winkler elastic foundation stiffness parameters, different displacement boundary conditions, the effect of size of the circular cutout and orientation of the elliptical cutout, and the influence of GPL weight fraction are discussed in several tabular and graphical data in detail.

Flow and acoustics in a model rocket flame deflector and deflector cover

The design of a rocket launch environment is a complex process with many different aspects that are highly interconnected. Acoustics, which is one of these, should be investigated in detail due to possible devastating effects on the launch vehicle, crew, and launch environment. This study uses a numerical method to consider a passive noise reduction method applied to a supersonic jet impinging on an inclined flame deflector to decrease the acoustic loads on the launch vehicle and noise levels in the far-field. In a supersonic jet impinging on an inclined flat plate configuration, acoustic waves that travel upstream originate from the impingement and wall jet regions. These upstream traveling waves are a combination of the acoustic waves that are produced by the high speed jet flows in the wall jet region and acoustic waves that reflect from the impingement wall. Due to the inclination of the impingement plate, these waves either travel to the far-field in the upstream direction or travel towards the free-jet region interacting with the high speed flow near the nozzle lip. This interaction can create a self sustaining feedback loop, which can cause acoustic tones to appear in the near- and far-field spectra. It is the aim of the present study to block the upstream traveling waves by introducing a second inclined wall with a circular cut-out between the nozzle exit and the impingement plate. Different configurations with different wall locations and cut-out sizes are investigated using a Detached Eddy Simulation CFD solver and an acoustic solver that is based on the Ffowcs Williams and Hawkings analogy. The mechanisms for the establishment of the feedback loops are examined.

Dynamic Stability Analysis of Square Isotropic/Laminated Composite Plates With Circular Cutout Subjected to Non-Uniform Follower Edge Load With Damping

The present investigation deals with the study of vibration and dynamic instability behaviour of square isotropic/laminated composite plates with circular hole subjected to partially distributed follower edge forces using finite element method. The first order shear deformation theory is used to model the plate, considering the effects of shear deformation and rotary inertia. The modal transformation technique is applied to the resulting equilibrium equation for subsequent analysis. Structural damping is introduced into the system in terms of equivalent viscous damping to study the significance of damping on stability characteristics. The effects of cutout size, load width, boundary condition, ply orientation, direction control of the load and damping parameters are considered for the stability behaviour of the plates. The results show that under follower loading, the system is susceptible to instability due to flutter alone or due to both flutter and divergence, depending on system parameters.

Parametric Instability of Stiffened Plates with Cutouts

The dynamic instability behaviour of stffined plates with cutout is of great technical importance for understanding the behaviour of the system. In the present study, dynamic instability behaviour of stffined plates with cutouts are investigated by using theJinite element method. The method of Hill's infinite determinants is applied to analyze the dymmic instability regions. Rectangular stilfened plates with cutouts possessing diferent boundary conditions, aspect ralios, varying mass and stffiess properties and varying number of stiffeners have been analyzed for dynamic instability. The influence of various parameters like effects of size of cutout, load position, aspect ratios, and boundary condition, other paramelers of stffined plates have been studied. The method highlights interesting effects when stffined plate with cutout is subjected to uniftrm in-plane edge load. In the structural modelling, the plate and the stffiner are treated as separate elements where the compatibility between these two types of elements are maintained. The present approach is moreflexible than any otherJinite element modelling in that the mesh division is independent of the location of the stiffeners.

Strength Prediction and Damage Assessment of Laminated Composite Plates With Rectangular/Square Cutout Using Finite Element Method

The progressive failure analysis of symmetrically laminated rectangular composite plate [0/+45/-45/90]2s with square/rectangular cutout under uniform uniaxial compression loading is carried out using finite element method. Hashins failure criterion is used to predict the failure of lamina. A parametric study has been carried out to study the influence of square/rectangular cutout size, cutout orientation and plate thickness on the ultimate failure load of laminated composite plate under uni-axial compression loading. Ultimate failure loads were computed for six different laminate configurations [0/+45/-45/90]2s, [75/-60/30/-15]2s, [0/90]4s, [-45/45]4s, [15/-75]4s, [30/-60]4s. It is observed that the laminate stacking sequence, plate thickness , cutout size and cutout orientation has substantial influence on the ultimate failure load of notched composite plates.

Free vibration of arbitrarily shaped plates with complex cutouts

In this paper, an exact model for free vibration analysis of arbitrarily shaped plates with various cutouts under general elastic boundary conditions is established. It combines the artificial connecting spring technique with the domain segmentation integral method (DSIM) proposed by the author. The arbitrarily shaped plate with cutouts is decomposed into several arbitrarily shaped subdomains based on the cutouts. The continuity conditions at the interconnecting interfaces of the subdomains are realized by artificial coupling springs. The energy expressions of the free vibration of the subdomain with arbitrary shape is calculated analytically or semi-analytically by using the DSIM. That is, in order to simplify the energy expressions into definite integrals, the arbitrarily shaped integration domain of the energy integrals is divided into several trapezoid domains with curved sides, and then the penalty method and Gram–Schmidt orthogonalization process are combined to generate the admissible functions for calculation. When the contour curve equations of the plate enable the energy integrals to be analytically calculated, the model can obtain the exact solution of free vibration of an arbitrarily shaped plate with various cutouts under general elastic boundary conditions; otherwise, the semi-analytic results can be obtained by combining Gauss–Legendre method. The convergence and accuracy of the proposed model are verified by comparing the numerical examples with results available in the literatures. The vibration characteristics of several complex shaped plates with various cutouts are studied. Taking elliptical plates with a rhombic cutout as examples, the effects of cutout size and position on the vibration characteristics of the plate are discussed. These new results can serve as benchmarks for further research.

Buckling analysis of laminated composite rectangular plates with diamond cut-outs

The buckling analysis of the composite laminated plates with various diamond cut-out parameters has been studied using finite element analysis. Parameters such as the orientation, effect of size, positions of the diamond cut-out, and ply orientations are evaluated. Results are compared to previously published research and demonstrate strong agreement with the current findings. The results show that the buckling load decreases with increase in cut-out size ratio. The dimensions of the cut-out play a vital role in determining the buckling effects, as mass of the plate reduces. Additionally, steady growth is observed for ply-orientations ([(0/90)2]s, [(15/-75)2]s, [(30/-60)2]s and [(45/-45)2]s) with increase in mode numbers.

Ultimate strength of hyper-ellipse flanged-perforated plates under uniaxial compression loading

Abstract In order to address the impact of the perforated parameters on the mechanical properties of the plate, the ultimate strength of hyper-ellipse flanged-perforated plates under uniaxial compression stress is numerically investigated in this article. The four edges of the flanged-perforated plate are only supported in the out-of-plane direction while the plate is exposed to uniaxial compressive loads. The impact of the cutout size, flange height, cutout position, rotation angle, and cutout form on the ultimate bearing capacity of the perforated plate with varied thicknesses is investigated and compared through a series of elasto-plastic buckling analyses using the ANSYS software. The structure’s stress and deformation analysis is then used to explain the results of the ultimate strength test. The flange efficiently raises the maximum bearing strength of the structure with cutouts. For the limit strength of thick plate, the cutout size, elliptical shape, cutout rotation angle, and cutout position have considerably more of an impact than they do on the maximum bearing capacity of thin plate. The findings can assist the structural layout of this sort of perforated plate, and the right cutout parameters should be chosen in accordance with the various performance specifications.

Enhancing delamination resistance with intralaminar stiffness tailoring: A numerical study of variable stiffness composites

In general, strategies and techniques involving intralaminar stiffness tailoring are primarily used to improve compressive capacity (buckling and post-buckling) or tensile properties rather than interlaminate toughness for composites. However, in this work, we show the potential of utilizing intralaminar stiffness tailoring to enhance delamination resistance by specifically investigating the perforated variable stiffness composite plate with a different layout of curvilinear fibers. Firstly, a standard finite element model with the typical cohesive interface to evaluate the delamination performance of different composites is established and is verified against the averrable experimental data of intact constant stiffness composites. Then, two kinds of curvilinear fibers for the perforated composite plates under the Mode I and Mode II delamination test are investigated considering the different fiber layouts and the size of the central cutout. The reaction force–displacement curve and the R-curve of the composites with the curvilinear fibers are obtained to show the enhancement effect of the intralaminar stiffness tailoring on the delamination resistance. The interlaminate toughness of the curvilinear fibers laminate can overperform the straight fibers laminate up to 71% and 63% in the mode Ⅰ and mode Ⅱ cases (r = 8). The underlying mechanism is discussed in detail to inspire new ideas for intra-laminar stiffness tailoring to improve interlaminar toughness.

Comparison between linear and nonlinear buckling loads of FGM cylindrical panel with cutout

This paper investigates the influences of effective parameters on the Difference between the Linear and Nonlinear Buckling Loads (DLNBL) of Functionally Graded Material (FGM) perforated cylindrical panel. In this regard, the panel was simulated using spline finite strip method. The linear and nonlinear buckling loads of the panel were obtained from linearized eigenvalue method and nonlinear geometric analysis. A comparison was made between the results obtained from the model developed in this study and those available in the literature to evaluate the validity of the results obtained from the model. Through a parametric study, the influences of different effective parameters such as cutout size, cutout shape, ratio of radius to thickness and power of FGM on the difference between the linear and nonlinear buckling loads of the panel were investigated. Although for the panels without cutout, the DLNBL was about 2 percent, it reached to 40 percent for the panels having cutout. As the cutout area increases or cutout shape changes from circle to long ellipse, the DLNBL increases significantly. Moreover, the DLNBLs obtained for shallow and FGM panels were lower than those for the deep and isotropic panels. The results obtained indicate that the buckling load obtained from linearized eigenvalue method is overestimated by about 40% for the FGM panel having long elliptical cutout. Finally, contour graphs were derived to determine the maximum difference between linear and nonlinear buckling loads of FGM panel based on the shape of cutout, size of cutout and ratio of radius to thickness of the panel. According to these graphs, the linearized eigenvalue method is not a proper method to obtain the buckling load of panels having long elliptical cutout and deep panels having medium elliptical cutout.

Compression Strength Estimation of Corrugated Board Boxes for a Reduction in Sidewall Surface Cutouts-Experimental and Numerical Approaches.

Corrugated cardboard boxes are generally used in modern supply chains for the handling, storage, and distribution of numerous goods. These packages require suitable strength to maintain adequate protection within the package; however, the presence and configuration of any cutouts on the sidewalls significantly influence the packaging costs and secondary paperboard waste. This study aims to evaluate the performance of CCBs by considering the influence of different cutout configurations of sidewalls. The compression strength of various B-flute CCB dimensions (200 mm, 300 mm, 400 mm, 500 m, and 600 mm in length, with the same width and height of 300 mm), each for five cutout areas (0%, 4%, 16%, 36%, and 64%) were experimentally observed, and the results were compared with the McKee formula for estimation. The boxes with cutout areas of 0%, 4%, 16%, 36%, and 64% showed a linear decreasing tendency in compression force. A linear relationship was found between compression strength and an increase in cutout sizes. Packages with 0% and 4% cutouts did not show significant differences in compression strength (p < 0.05). Furthermore, this study shows a possible way to modify the McKee estimation for such boxes after obtaining empirical test data since the McKee formula works with a relatively high error rate on corrugated cardboard boxes with sidewall cutouts. Utilizing the numerical and experimental results, a favorable estimation map can be drawn up for packaging engineers to better manage material use and waste. The results of the study showed that the McKee formula does not appropriately estimate the box compression strength for various cutout sizes in itself.

Comparative study of cross-ply laminated composite materials and effect of buckling response with and without cutouts

In this work, finite element analysis has been done along with experimental test and conducted using numerical and experimental tests of the buckling response of quasi-static compressive loading of six layers woven cross-ply laminated composite material [0º/90º/0º] with centrally square and circular cutouts. The effect of cut-out shape and its size with a buckling load were obtained experimentally and numerically. Compression experiment has been performed by using INSTRON machine, and the experimentally obtained buckling loads are compared with a numerical results obtained by ANSYS simulation program. Both experimental and numerical results are showing good agreement. It is noticed that the buckling load of the composite plate has been decreased with the increasing of the size of cutout. The cutout area, cutout ratio (d/w), fiber weight, plate thickness and fiber type of the plate has a major effect to the load of the cross-ply laminated composite plates.

Lessons learned from the two largest Galaxy morphological classification catalogues built by convolutional neural networks

ABSTRACT We compare the two largest galaxy morphology catalogues, which separate early- and late-type galaxies at intermediate redshift. The two catalogues were built by applying supervised deep learning (convolutional neural networks, CNNs) to the Dark Energy Survey data down to a magnitude limit of ∼21 mag. The methodologies used for the construction of the catalogues include differences such as the cutout sizes, the labels used for training, and the input to the CNN – monochromatic images versus gri-band normalized images. In addition, one catalogue is trained using bright galaxies observed with DES (i < 18), while the other is trained with bright galaxies (r < 17.5) and ‘emulated’ galaxies up to r-band magnitude 22.5. Despite the different approaches, the agreement between the two catalogues is excellent up to i < 19, demonstrating that CNN predictions are reliable for samples at least one magnitude fainter than the training sample limit. It also shows that morphological classifications based on monochromatic images are comparable to those based on gri-band images, at least in the bright regime. At fainter magnitudes, i > 19, the overall agreement is good (∼95 per cent), but is mostly driven by the large spiral fraction in the two catalogues. In contrast, the agreement within the elliptical population is not as good, especially at faint magnitudes. By studying the mismatched cases, we are able to identify lenticular galaxies (at least up to i < 19), which are difficult to distinguish using standard classification approaches. The synergy of both catalogues provides an unique opportunity to select a population of unusual galaxies.