Number Of Cutouts Research Articles

Analytical justifications of constructive parameters of bionic colters for vertical soil treatment

Bionic coulters imitate natural forms and functions, which help reduce energy costs for soil tillage. The aim of the research was to justify the design and structural parameters of turbo discs (coulters) for vertical tillage based on the principles of bionic reverse engineering. Using this method, an equation for the shape of the turbo discs (coulters) was derived, which was obtained by approximating the shell of the argonaut (Argonauta argo). The equation takes into account the main structural parameters of the turbo discs: diameter Dd, cutout height Hm, wave height Hw, number of cutouts n, and spiral coefficient k. As a result of analytical studies on the interaction process between a solid disc and plant residues, the optimal diameter value was determined to be Dd=460 mm under the condition of submerging stems with a thickness of 10-20 mm to a depth of 80 mm. The analytical studies confirmed that the presence of cutouts on the disc prevents stem deflection and ensures better stem capture. In analysing the obtained dependencies using the Wolfram Cloud software package, the optimal values for the cutouts were determined: cutout height Hm=40 mm, number of cutouts n=8. The presence of waves on the disc surface ensures that the interaction with plant residues is independent of their position on the field surface and creates conditions for vertical soil tillage. It was found that, to minimize specific cutting resistance and maximize the degree of soil fragmentation, the optimal wave parameters for the coulter are a wave height of Hw=24.4 mm. The justified parameters of the coulters provide the best balance between soil fragmentation efficiency and reduction in energy consumption for soil tillage. The obtained results can be used to adapt existing agricultural machinery to the new structural parameters of coulters to improve its efficiency.

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.

Evaluation of tensile properties of hybrid kevlar-glass reinforced epoxy composite for multi holes configuration

Abstract Most modern structures are comprised of synthetic composites with more number of cut outs. For the design of synthetic composite with varying shapes with different sized cut-outs are often used in engineering structures. The effects of stress concentration factor and tensile behaviour has to be thoroughly investigated for providing better design aids to be utilized by design engineers. The present paper focuses on the tensile behaviour of the Kevlar and glass fiber reinforced hybrid polymer composite by varying size and position of the cut outs. The test specimens are prepared according to the ASTM standard D3039. The composite laminates are prepared by traditional hand layup method. The overall dimension of plates were 25 mm*250 mm (width*length) and with the gauge length was 110 mm. These plates were drilled with the circular holes of 8 mm and 5 mm. The larger hole of diameter 8 mm was drilled at centre of all the specimens and smaller holes of diameter 5 mm was drilled on either sides of 8 mm hole. The pitch for smaller 5 mm holes were increased in the order of 0, 15, 20, 25 and 30 mm respectively. The specimen with smaller holes at 25 mm pitch showed highest allowable stress of 97.22 MPa. The experimental results were compared to find the optimum position for placing the holes. This research also intends to find out if there exists any relationship between the pitch, diameter of smaller and larger holes present in the specimen.

DETERMINATION OF THE RATIONAL PROFILE FOR THE DISK WORKING TOOL WHEN CULTIVATING OF SOD PODZOLIC SOILS

Maintaining soil fertility is one of the main objectives of agricultural production. An important factor in soil fertility is its optimal structure. For the minimum cultivation of soil widely used equipped with spherical cut-off discs heavy harrows. The purpose of their use, along with others, in the cultivation of heavy soils, for example, chernozems, is the depression of soil boulders and, thus, the optimal structure. In the conditions of intensification of agricultural production under the influence of such soil-working tools in the cultivation of malocontuitive sod-podzolic soils and running gears of mobile equipment, the destruction of the soil structure, the reduction of the number of agronomically valuable water-supply units, and the spread of soil. Thus, for the cultivation of such soils, it is necessary to use discs of another profile, which would ensure the minimum destruction of agronomically valuable watertight aggregates. In order to create such a working body, the process of structuring the agronomically valuable water-conserving aggregates, factors influencing it and analyzing the energy criteria for the formation of a water-tight structure is considered. The features, which arise during mechanical cultivation of soil, influence of cultivation on its structure and features of the stress-strain state of soil are studied. A mathematical model is developed that allows calculating the stress state of the soil and designing the most rational form of disk working bodies. In the conducted studies, the influence of the depth of cultivation, the number of cutouts, the size of the cutout angle and the length of the chord of the projection were studied. On the basis of the developed mathematical model, a rational profile of the disk working organ for the cultivation of small-coupling sod-podzolic soils was obtained and its tests were performed, which showed a decrease of the erosion-dangerous particles of the soil by (<0,25 mm)  24%.

Influence of shape, size and location of cutouts on crashworthiness performance of aluminium conical frusta under quasi-static axial compression

Abstract The influences of different shape, size and number of lateral cutouts at various locations on the load-bearing capacity, buckling behaviour and energy absorption (Eabs) characteristics of aluminium conical frusta under quasi-static axial loading condition were studied from both experimental and numerical procedures. In this regard, 18° semi-apical angled aluminium conical (AC18) frusta were fabricated through the metal spinning process; and circular, square, and trapezoidal shapes of cutouts with required dimensions were introduced at various lateral locations of the frustum. These conical frusta were subjected to quasi-static axial loading at a rate of 2 mm/min using a universal testing machine (UTM), and the corresponding load-deformation characteristics were recorded for axial compression of 50 mm from its original height. In addition to that, similar to experimental studies, Finite Element Analysis (FEA) was performed with conical frusta having various cutouts using ABAQUS® finite element software to study the influence of cutouts on the changes on crashworthiness performance of conical frusta. From both studies, it is observed that the energy absorption capacity of 18° semi-apical angled aluminium conical frusta was found to be decreasing in the range of 3.67%–47.60% according to the shape, size, number and location of cutouts. Further, the load resistance parameters such as first peak load (Pfst), maximum peak load (Pmax) and average load (Pavg) also are found to be decreasing with an increase of cutout size. The change of cutout location from mid-height to three-fourth from the base of the frustum also resulted in a reduction of Eabs capacity, regardless of shape, size and number of cutouts. From these studies, it observed that the energy absorption characteristic of conical frusta having circular cutouts are found to be better than the conical frusta having square and trapezoidal cutouts at same locations. It is also observed that the Eabs capacity of conical frusta having cutouts was found to be non-linearly decreasing with the linear increase in the number, location, shape and size of cutouts. The specimens with a large-size of cutouts had exhibited large deformation over the cutout region that led to an unstable non-linear global buckling during axial compression. Consequently, their Eabs capacity was found to be decreased significantly as compared with the conical frusta with a small size of cutouts. The specimens with the small size of the cutouts exhibited progressive local buckling during axial compression, and they exhibited better energy absorption characteristics as compared with the conical frusta with large size of cutouts.

Numerical method based parametric investigation of isotropic annular plate

Annular plates play a vital role as a part of machine elements for different applications, hence characterization and investigation of annular plate for different parameters is of crucial importance. The current work deals with investigation of isotropic annular plate to study the behavior of annular plate for variation in boundary conditions, number of cutouts and type of cutouts in the annular plate on its static and dynamic behavior. The numerical method is successfully utilized for determination of effect of various parameters on stresses induced, deflection, natural frequency and mode shape.

Static bending and buckling of perforated nonlocal size-dependent nanobeams

Due to their superior electronic, mechanical and thermal properties of nanomaterials, they have been widely used in nano-electromechanical systems (NEMS). Nanobeams are common elements in these systems. In some situations perforation is necessary in nanostructures for manufacturing process and technological reasons. Therefore, studying of static bending and buckling behavior of perforated nanobeams is essential for accurate and reliable design of nanostructures. Because of the importance of size effects on the mechanical performance of these structures the size-scale effect should be considered in their design. In this paper an analytical model capable of predicting bending response and critical buckling load of perforated nanobeams is presented for the first time. The model is formulated based on both Timoshenko and Euler–Bernoulli beam theories with nonlocal differential form of Eringen model. The present model is validated by comparing the obtained predictions with that of the available published results in literature for fully beam. Effects of size-scale and perforation parameters (perforation size and number of cutouts) on the static and buckling behavior of the perforated nanobeams are analyzed.

Buckling of axially compressed composite cylinders with geometric imperfections

Cylindrical shell structures buckle at service loads which are much lower than their associated theoretical buckling loads. The main source of this discrepancy is the presence of various imperfections which are created on the cylinder body during different processes as manufacturing, handling, assembling and machining. Many cylindrical shell structures are still designed against buckling based on the experimental data introduced by NASA SP-8007 as conservative lower bound curves. This study employed the numerical based Linear Buckling mode shape Imperfection (LBMI) method and modified it using a stochastic method to assess the effect of geometrical imperfections in more details on the buckling of cylindrical shells with and without the cutout. The comparison of results with those obtained from the numerical Simcple Perturbation Load Imperfection (SPLI) method for cylinders with and without cutout revealed a good correlation. The effect of two parameters of size and number of cutouts on the buckling load was investigated using the linear buckling and Modified LBMI methods. Results confirmed that in cylinders with a small cutout inserting geometrical imperfection using either SPLI or modified LBMI methods significantly reduced the value of the predicted buckling load. However, in cylinders with larger cutouts, the effect of the cutout is dominant, thus considering geometrical imperfection had a minor effect on the buckling loads predicted by both SPLI and modified LBMI methods. Furthermore, the modified LBMI method was employed to evaluate the combination effect of cutout numbers and size on the buckling load. It is shown that in small cutouts, an increasing in the cutout size up to a certain value resulted in a remarkable reduction of the buckling load, and beyond that limit, the buckling loads were constant against D/R ratios. In addition, the cutout number shows a more significant effect on decreasing the buckling load at small D/R ratios than large D/R ratios.

Free vibration analysis of a thin rectangular plate with multiple circular and rectangular cut-outs

The present work is to investigate the variation in the natural frequency of a rectangular plate with the change in position of cut outs of different sizes along its diagonal and major axis line by considering different aspect ratios of plates. In this regard the free vibration analysis of an isotropic rectangular plate of various aspect ratios with different sizes of multiple circular and rectangular cut-outs is carried out by using an Independent coordinate coupling method (ICCM) under simply supported boundary condition. The ICCM utilizes independent coordinates separately for plate domain and hole domain, in which the reduced mass and stiffness matrices can be derived, by matching the deflection conditions for each hole imposed on the expressions. The resulting equation is useful for the calculation of the Eigen values. The position, size, and number of cutouts have been varied in all the possible ways to investigate their effects on the natural frequency of the rectangular plate.

Thermal buckling analysis of functionally graded perforated annular sector plates using 3D elasticity theory

ABSTRACTThermal buckling of annular sector plates with circular cutouts made of functionally graded material is analyzed in this article. Graded material is considered with two parts of ceramic structure made of zirconia and metal structure which is aluminum. Unlike most conducted research, the direction of property change is observed in three main directions. Thermal loading is assumed as a uniform increase in temperature influencing the whole sector. 3D-finite element method based on elasticity theory is used in this analysis, which resets first and second variations of potential energy of the sector to zero to find equilibrium and stability equations, respectively. Green’s nonlinear strain–displacement relations are used to obtain geometrical stiffness matrix. In the finite element method, unlike most studies, a 3D eight-nodded element is used, which has nodes in the direction of thickness. The circular cutouts of the sector have added to the complexity of the analysis. The finite element formulation is coded in MATLAB. Finally, the effect of different parameters such as dimension and number of cutouts, power law index, and orientation of graded material on the critical thermal buckling temperature is studied.

Thermal Buckling Analysis of Perforated Functionally Graded Plates

In this research, the buckling behavior of functionally graded (FG) plates under thermal loading is investigated based on finite element analysis. It is assumed the plate is subjected to a uniform temperature rise across plate thickness. First-order shear deformation theory (FSDT) is utilized for developing the solution method. By using an appropriately designed mesh structure for a perforated plate, the critical thermal buckling temperature is obtained by numerical solution of the problem based on finite element method (FEM). The FG plate is perforated by multiple cutouts. The number of cutouts is assumed one, two, four, or six. Also different geometrical shapes of cutouts including triangle, square, rhombus, pentagon, hexagon, and circle are considered. The influence of the number of cutouts and their geometrical shapes on thermal buckling response is investigated. The effects of the number of sides of cutouts from three (triangle) to infinity (circle) are discussed. Two different boundary conditions are taken into account. Also the influences of the distance between the cutouts and the orientation of cutouts on critical buckling temperature are studied. In addition, the effects of the orientation of ellipse cutouts are studied. Some remarkable conclusions are gained that can be useful in practical applications.

Free vibration analysis of functionally graded plates with multiple circular and non-circular cutouts

Cutouts are inevitable in structures due to practical consideration. In order to investigate the free vibration of functionally graded plates with multiple circular and non-circular cutouts, finite element method is used. The volume fraction of the material constituents is assumed to follow a simple power law distribution. The parameters considered in this paper are as follows: cutout size, cutout location, number of cutouts and different boundary conditions. It should be mentioned that free vibration for FG plates(such as rectangular/skew/trapezoidal/circular plates) with multiple cutouts has not been studied yet and hence the results out coming from this paper may be used as bench marks for future works.