Cutout Shape Research Articles

The numerical and experimental analysis of ratcheting behavior for 304 steel sheets under cyclic axial loading

The present study examines the effect of the thickness, cutouts numbers, and different cutouts shapes on the ratcheting behavior of 304 steel sheets under cyclic axial loading. The cutout shapes considered here are circular, triangular, and square cutouts. The effect of the number of circular cutouts in 304 steel sheets on ratcheting behavior is investigated. The Instron 8502 device is used to perform the experiments in which the cyclic axial loading is applied to six specimens with different cutouts and thicknesses at ambient temperature. The obtained results highlight the fact that reducing the thickness and increasing the number of cutouts in the sheets are attributed to the rise in the ratcheting displacement. Accordingly, the ratcheting displacement is more striking in the sheets with triangular cutouts. Notably, a numerical analysis is considered using the isotropic/kinematic nonlinear hardening model and FEM in ABAQUS software. Since a good agreement is seen between the numerical and experimental results, the analysis conducted in this study is reliable in terms of accuracy and authenticity.

On transient responses of sandwich plate with cutout using FEM

In the present research work, time-dependent transverse deflection responses of a sandwich composite plate with cutout have been analyzed by using lower-order theory in conjunction with the finite element approach. Initially, the sandwich structure with the cutout (square, pentagonal, hexagonal, and circular) is developed in the ANSYS platform using ANSYS parametric design language (APDL) code. The necessary material properties of the sandwich structure (face sheet and core) are assigned. The developed model has been discretized using 8 noded shell element (Shell 281). The structure is now assigned a simply supported end condition and uniformly distributed loading (UDL). Now, the numerical model’s accuracy is evaluated by comparing the simulated results to previously published literature’s results. The developed simulation model has been used further to investigate the effect of cutout ratios, cutout shape (square, pentagon, hexagon and circle) and core to face thickness ratio on the transient response of a square sandwich panel via new examples. The findings of the examples are analyzed and discussed in detail.

Nonlinear analysis of perforated composite plates under compression by experimental, semi-analytical and numerical methods

The purpose of this paper is to investigate the effects of different cutout shapes on the nonlinear behavior of perforated composite plates using experimental, numerical and semi-analytical methods and to present their capabilities. For analysis, the composite plates are subjected to a compressive load and different out-of-plane boundary conditions are applied to the lateral edges. Investigations are performed by various methods such as experimental tests, finite element method and a semi-analytical technique. For laboratory tests, a fixture has been designed and built that can create different boundary conditions on the lateral edges of perforated plates and can also test laminates up to 6 mm thick. On laminates, three types of openings are created in square, rectangular and elliptical shapes and the perforated laminates are tested with two types of boundary conditions, including clamped on all four edges (CCCC) and simply on two lateral edges and clamped on two ends (SSCC). These experiments are also simulated in the Abaqus finite element package, taking into account the considerations raised and with the nonlinear Riks method. Also, with similar assumptions in experimental and numerical methods, a semi-analytical method has been developed to compare the results and capabilities of different methods in nonlinear analysis of perforated laminates with different boundary conditions. In the last method, the displacement fields are approximated using Legendre functions and assuming the first-order shear deformation theory. Then, the nonlinear system of equilibrium equations governing the perforated plates is obtained through the principle of minimum total potential energy and is solved by the common method of quadratic extrapolation technique. Finally, the capabilities, advantages and disadvantages of each method, especially the fixtures made for this research, are discussed.

Study of effect of provision of cut-outs on axial collapse behaviour of circular aluminium tubes

Geometrical modification of thin-walled tubular structure is one of the innovative ways in the development for vehicle safety design. This research is developed in accordance with the need of investigation on behaviour of tubular structures with geometrical modifications like cut-outs under dynamic loading technique. Diamond and elliptical cut-out shapes are provided in multiple number arranged circumferentially in a single row on a tube surface. Tubes with cut-outs are loaded axially at three different velocities, corresponding to three different strain rates. Energy absorption characteristics like energy efficiency, specific energy absorption, peak collapse force, mean collapse force and efficiency of peak force reduction at the initiation of tube deformation are calculated and compared using finite element (FE) based ABAQUS/Explicit® software. Split-Hopkinson Pressure Bar (SHPB) is modelled in the FE software to understand the material behaviour under high strain dynamic loading. Johnson-Cook material model parameters are incorporated in the study to understand the strain rate sensitive behaviour of aluminium alloy material. Results revealed that providing diamond and elliptical cut-outs on tube is much efficient than providing circular cut-outs on tube, in terms of percentage peak load reduction as well as energy efficiency of structure. It was observed that number of cut-outs influences the polygonal deformation pattern of tube with cut-outs. Overall study significantly helps to achieve the aim of improving vehicle crashworthiness characteristics by implementing cut-outs in a crash frame.

Fundamental frequencies of composite rectangular plates with different cut-outs

This paper demonstrates the effects of various parameters on the fundamental frequency of a rectangular laminated composite plate with different shape of cutout (i.e. elliptical, rectangular and diamond shaped cutout). The shape and size of the cutout, fiber-orientation angle and boundary condition of the rectangular plate are considered parameters in the present study. Modal analysis was performed using finite element analysis to determine the fundamental frequency. The model has been validated using the published results. Fully clamped plate possesses the highest and cantilever plate possesses the lowest fundamental frequency. Plate with diamond shaped cutout shows the lower frequency than the plate with elliptical and rectangular cutout. The effect of fiber orientation angle depends on the boundary condition of the plate. As the cutout area increases, the fundamental frequency also increases, but for cantilever boundary, there is an inverse effect.

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.

Design and Analysis of Aircraft Wing Rib with Different Configuration for A380 model

The wing rib of an aircraft is a very critical part. It provides airfoil contour to the wing. Its principal role in wing structure is that to transfer load from skin to stringers or other parts of wing. Cut-outs in aircraft structural components such as wing spars and ribs are commonly encountered in practice. Cut-outs are often necessary for lightening holes, passages for wire bundles, hydraulic and fuel pipes, control linkages, accessibility for final assembly and maintenance inspections. The shape of the cutout is a important parameter where depends on the cutout shape the structural parameters may get varied. The main objective in here is to study about the influence of cutout in rib section with different cutout shapes. The Airbus A380 model is considered and the rib section for the model is modeled using Solidworksmodeling package and the model is analyzed for different cutout shapes. The model has the cutout shapes such as circle, ellipse and rectangle, where the circular hole is a most practiced method in recent models. The numerical analysis is carried out in ANSYS static structural analysis to find the structural parameters such as stress, strain, deformation and weight.

Effect of material type, cutout shape and temperature on stress and deformation analyses of thin plates

Effect of material type, cutout shape and temperature on stress and deformation analyses of thin plates

Axial Deformation of Shells at Higher Strain Rates using Buckling Initiators

Deformation mode of cylindrical shells and their peak load reduction is of prime importance in impact damage mechanics. In this study, numerical investigation is carried out for triggering mechanism induced in the thin-walled axially compressed short stubby shells, considering the damage occurred in vehicle crash or in any other protective equipment. The shells are studied for their initial buckling response under varying impact velocities for two different triggering configurations. Explicit simulation is carried out using ABAQUS/Explicit® to study the initial buckling of the shells by modelling Split Hopkinson Pressure Bar (SHPB) test setup. Initially, numerical scheme is validated using previously available study. Present analysis is carried out using diamond shaped triggering notches and these are configured in such a way that the shell will deform in particular buckling mode, under the impact of three different velocities i.e. 9 m/s, 20 m/s and 40 m/s. Effect of these notches and their pattern of arrangement on reduction in peak load and energy absorption characteristics are studied. Moreover, comparison is made between commonly used circular hole and diamond notch type cut-outs, in order to study the effect of above said parameters along with the energy absorbed, energy efficiency and specific energy absorption for the shells considered herein. By numerically impacting the shells in SHPB, it is observed that peak load reduction is higher in diamond notched shells as compared to circular hole shells. This was due to the geometry and size of the cut-outs considered in this study. Parameters like peak collapse load, energy absorbed, energy efficiency along with stress concentration around the notch are also observed and studied in this work in order to observe and compare the two shapes of cut-outs.

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.

Stability Performance of Perforated Stiffened Laminated Composite Plates Under the Influence of Environmental and Operational Loading Conditions Using FE Approach

Eccentrically stiffened plates are widely used as a structural component in many engineering applications. However, these structures are exposed to complex loading conditions, resulting in strength reduction leading to failure. This research aims to examine the stability performance of the perforated stiffened laminated composite plate subjected to non-uniform edge load under the influence of environmental conditions. Towards this, a robust and computationally efficient finite element (FE) formulation has been developed, where the plate is modeled using a 9-noded heterosis element to avoid the shear locking of the plate element and a 3-noded isoparametric beam element is adopted to model the stiffener by applying a displacement compatibility condition at the skin-stringer interface. A torsion correction factor is introduced in the beam formulation to account for the twisting of the stiffener. A unique dynamic technique is utilized to obtain the buckling load by employing two types of boundary conditions due to the non-uniform stress distribution in the perforated plate under environmental and operational loading conditions. An analysis is performed on the unstiffened plate to determine a suitable cutout shape, loading pattern and lamina scheme based on its improved stability performance. Unlike previous studies, several stiffener configurations are considered to comprehend the influence of temperature and moisture on the stability behavior of centrally placed cutout plates and obtain a stiffener configuration with improved performance. It is noticed that when the perforated stiffened plate is exposed to thermal or hygroscopic load close to a critical temperature or moisture, the buckling capacity drops suddenly in the plate attached to a stiffener of greater depth. Moreover, it is observed that when the stiffened plate is exposed to higher intensity of hygrothermal load, the plate’s buckling capacity drops significantly as the thickness of the plate reduces.

Clinical treatment planning for kilovoltage radiotherapy using EGSnrc and Python.

Kilovoltage radiotherapy dose calculations are generally performed with manual point dose calculations based on water dosimetry. Tissue heterogeneities, irregular surfaces, and introduction of lead cutouts for treatment are either not taken into account or crudely approximated in manual calculations. Full Monte Carlo (MC) simulations can account for these limitations but require a validated treatment unit model, accurately segmented patient tissues and a treatment planning interface (TPI) to facilitate the simulation setup and result analysis. EGSnrc was used in this work to create a model of Xstrahl kilovoltage unit extending the range of energies, applicators, and validation parameters previously published. The novel functionality of the Python-based framework developed in this work allowed beam modification using custom lead cutouts and shields, commonly present in kilovoltage treatments, as well as absolute dose normalization using the output of the unit. 3D user-friendly planning interface of the developed framework facilitated non-co-planar beam setups for CT phantom MC simulations in DOSXYZnrc. The MC models of 49 clinical beams showed good agreement with measured and reference data, to within 2% for percentage depth dose curves, 4% for beam profiles at various depths, 2% for backscatter factors, 0.5 mm of absorber material for half-value layers, and 3% for outputfactors. End-to-end testing of the framework using custom lead cutouts resulted in good agreement to within 3% of absolute dose distribution between simulations and EBT3 GafChromic film measurements. Gamma analysis demonstrated poor agreement at the field edges which was attributed to the limitations of simulating smooth cutout shapes. Dose simulated in a heterogeneous phantom agreed to within 7% with measured values converted using the ratio of mass energy absorption coefficients of appropriate tissues andair.

Design of Reservoirs Enabling Stress-Induced Sequential Release Systems.

Mechanical stress is recognized as a principle for opening enclosed compartments through compression, stretching, or shear, eventually resulting in the onset of a diffusion-controlled release. Here, we hypothesized that the geometrical design of cavities (cut-outs) introduced as containers in elastic polymer substrates and sealed with a brittle coating layer would enable a pre-defined release of different compounds by stress concentration phenomena. Design criteria such as cut-out shapes, orientations, and depths were initially assessed for suitably different stress concentrations in computational models. In substrates fabricated from polydimethylsiloxane by photolithographic techniques, the local strains at horizontal rectangular, circular, and vertical rhombus-shaped cut-outs systematically increased under horizontal stretching as proposed. When filled with model compounds and coated with poly(n-butyl cyanoacrylate), a pre-defined induced breakage of the coating and compound release was confirmed upon continuous uniaxial stretching. This proof of concept demonstrates how device design and functions interlink and may motivate further exploration in technology and medicine for deformation-induced on-demand dosage applications.

Influence of cut-out shape on the dynamic behavior of carbon nanotubes reinforced functionally graded plates

This research investigates the effects of cut-out on the dynamic behaviour of functionally graded carbon nanotube reinforced composite (FGCNTRC) plates. Finite element method (FEM) is utilized and SHELL181 type element of the ANSYS Workbench 17.2 program is utilized. To understand the vibration characteristics of the FG plates, various shapes of cut-outs such as triangular, square, rectangular, hexagonal, circular etc are considered. For comparison, solid FGCNTRC plate is modeled and natural frequencies of plates integrated with cut-outs of different shapes are determined using free vibration study. The mode superposition method is used to address the harmonic response analysis problem keeping the damping ratio constant. The stress, phase changes and displacement responses for definite frequency ranges have been used to interpret the findings. To learn more about the effects of cut-outs on the dynamic response, the plates are designed considering various grading patterns. The findings show that the shape of cut-outs significantly affects the harmonic responses as well as the fundamental frequency of the FG plates and are also depending on the grading patterns of these plates.

Progressive axial crushing behaviour of Al6061-T6 alloy tubes with geometrical modifications under impact loading

Axial crushing of tubes with multiple patterns of cut-outs is studied using numerical analysis. Commercially available finite element ABAQUS/Explicit® package is used to simulate the model under impact loading condition. Split-Hopkinson Pressure Bar (SHPB) is modelled to dynamically test the tube specimens with and without cut-outs. Number, size, and shape of cut-outs are kept constant in all specimens to have a constant weight reduction. In order to improve the crashworthiness characteristics of tubes, cut-outs are arranged on a tube surface along the circumferential and longitudinal direction in multiple rows. Crashworthiness parameters i.e., peak and mean collapse load, crushing efficiency, energy absorption characteristics are studied. The results revealed that a moderate weight reduction of tube can significantly affect the crushing characteristics of tube. In terms of load characteristic values, only 1% of weight reduction in modified tube samples has helped in 4.46% peak load reduction as compared to the normal tube, and crushing efficiency of the modified tube (T2) is found to be 2.17% higher than normal tube (T). In terms of energy absorption characteristic values, 1% of weight reduction in modified tube samples has helped in 1.95% reduction in energy absorption capacity as compared to the normal tube, and energy efficiency of modified tube (T2) is found to be 2.56% higher than the normal tube (T). After arranging the cut-outs in a multiple pattern, the location of cut-out is also seen to be influencing on the tube behaviour. It helps the tube to reduce the initial peak collapse load and optimize the mean collapse load. Further, force–deformation characteristics are also discussed to improve the crashworthiness characteristics of tube under impact load.

Compressive Failure Behaviour of Kevlar Epoxy and Glass Epoxy Composite Laminates Due to the Effect of Cutout Shape and Size with Variation in Fiber Orientations

The increasing trendof constructing componentsmade of composite laminates is due tothe flexibility intailoring their properties and high strength-to-weight ratio. Nevertheless, most practical components involve cutout features for fastening and these cutouts could significantly reduce the strength of the laminate. Due to its importance, many studies were conducted to study the effect of circular cutouts however, there is lack of information regarding the effect of various cutout shapes. Therefore, this study aims to investigate the compressive failure behaviour of Kevlar Epoxy and Glass Epoxy composite laminates due to different cutout shapes and sizes with variation in fiber orientations. Finite element software, ANSYS were used to simulate the deformation and failure behaviour of the laminates under compressive load. Prior to that, mesh convergence analysis and numerical validation were performed. Failure analysis was conducted for various cutout shapes (square cutout, diamond cutout, and circular) and size, based on Maximum Stress Theory. The results show that the existence of the cutouts on the composite laminates have reduced up to ten times the strength of the laminated composite plates. This information regarding the failure behaviour is important when designing components made of composite laminates under compression.

An Investigation of the Influence of Various Shaped Cutouts on the Free Vibration Behavior of Sandwich Structures

The current study deals with free vibration analysis of a sandwich beam in presence of different cutouts. PVC foam and glass fiber were used for the core and surface layers of the sandwich structures, respectively. First 6 frequencies of the sandwich structures were determined for different cutout shapes to see the effect of cutout shapes on the free vibration behavior of sandwich structures. For this, sandwich beams with different cutout shapes but with the same area were modeled. To see the effect of cutouts-shape only the shape of cutouts was changed and all other parameters were kept unchanged. Analyses were performed by using ANSYS apdl commercially available software. The analysis gives information about the influence of the cutout shape on the first six natural frequencies of the sandwich structures. From the results, it was observed that the changes of cutout shapes caused a significant decrease or increase in natural frequencies of sandwich structures beam depending on the cutout shape.

Dynamic instability analysis of perforated stiffened laminated composite panels subjected to non-uniform in-plane edge load under hygrothermal condition

A robust and computationally efficient finite element (FE) formulation has been developed in an effort to understand the parametric instability behaviour of a perforated stiffened composite panel subjected to a pulsating non-uniform edge load under a hygrothermal environment. The panel is modelled using a 9-noded heterosis element to avoid shear locking, whereas the stringer uses a 3-noded isoparametric beam element with a displacement compatibility condition employed at the skin–stringer​ interface. Due to the non-uniform distribution of stress in the perforated panel as a result of exposure to environmental and mechanical loading conditions, a unique dynamic technique has been implemented to account for the instability performance by employing two types of boundary conditions. In the current investigation, an unstiffened panel is initially obtained based on the highest value of the dynamic instability opening (DIO) and the unstable excitation frequency of the panel for different lamina schemes, cutout shapes, and loading conditions. The obtained unstiffened panel is further investigated for various stiffener configurations to determine a highly unstable perforated stiffened panel based on the DIO value and instability zone frequency range. Detailed parametric studies are then carried out considering the cutout sizes, cutout orientation, panel’s aspect ratio, and stiffener depth to understand the parametric instability behaviour of the panel in a hygrothermal environment. It is found that moisture significantly influences the dynamic instability behaviour of the perforated stiffened panel compared to the temperature exposure by shifting the instability zone towards the lower frequency. The width of the instability region of the stiffened panel broadens abruptly as the magnitude of the applied static in-plane edge load enhances. Also, for certain combinations of the dynamic and static load factors, the lower bound of the instability region reduces to zero, resulting in fluttering. In general, it is observed that stiffer the panel, wider is the instability zone with a higher unstable excitation frequency range.

Surrogate Modeling Accelerated Shape Optimization of Deployable Composite Tape-Spring Hinges

Composite tape-spring hinge (CTSH) is a simple yet elegant mechanical component for various deployable space structures. This paper formulates and addresses cut-out shape optimization of a CTSH, which is seldom touched upon in literature. Both the maximum strain energy stored during the folding process as well as the maximum bending moment during deployment were maximized in a concurrent way, and the multi-objective optimization problem was realized by merging data-driven surrogate modeling and shape optimization. Four different surrogate modeling techniques (radial basis function, kriging, Gaussian process regression, and artificial neural network) are evaluated and compared. The maximum stored strain energy at the fully folded state and the maximum bending moment during deployment for the optimal CTSH are increased by 50 and 35%, respectively, compared to the initial design under a previously developed composite failure criterion as constraint. To ensure reproducibility and foster future research, we publicly share our full implementation with the source codes and trained models with the community.

Optimal design of tube flexure cut-out geometries for deployment performance

A design methodology is proposed for deployable tube flexures made of ultra-thin carbon fiber composite. The methodology is developed to achieve desired stowage and deployment performance in the absence of material failure. The cut-out shape in the tube flexure is determined by means of a Bayesian optimization technique. The objective function is defined based on both desired moment characteristics and Hashin failure criteria. Multiple cut-out parameterization schemes are presented. Bayesian optimization is shown to be effective and significant performance improvements are achieved thought use of spline-based optimization in comparison to more conventional forms. The efficiency of the approach is validated via experiment.