Cylinder Wall Thickness Research Articles

3D-printed bioinspired spicules: Strengthening and toughening via stereolithography

Recently, the replication of biological microstructures has garnered significant attention due to their superior flexural strength and toughness, coupled with lightweight structures. Among the most intriguing biological microstructures renowned for their flexural strength are those found in the Euplectella Aspergillum (EA) marine sponges. The remarkable strength of this sponge is attributed to its complex microstructure, which consists of concentric cylindrical layers known as spicules with organic interlayers. These features effectively impede large crack propagation, imparting extraordinary mechanical properties. However, there have been limited studies aimed at mimicking the spicule microstructure. In this study, structures inspired by spicules were designed and fabricated using the stereolithography (SLA) 3D printing technique. The mechanical properties of concentric cylindrical structures (CCSs) inspired by the spicule microstructure were evaluated, considering factors such as the wall thickness of the cylinders, the number of layers, and core diameter, all of which significantly affect the mechanical response. These results were compared with those obtained from solid rods used as solid samples. The findings indicated that CCSs with five layers or fewer exhibited a flexural strength close to or higher than that of solid rods. Particularly, samples with 4 and 5 cylindrical layers displayed architecture similar to natural spicules. Moreover, in all CCSs, the absorbed energy was at least 3–4 times higher than solid rods. Conversely, CCSs with a cylinder wall thickness of 0.65 mm exhibited a more brittle behavior under the 3-point bending test than those with 0.35 mm and 0.5 mm wall thicknesses. CCSs demonstrated greater resistance to failure, displaying different crack propagation patterns and shear stress distributions under the bending test compared to solid rods. These results underscore that replicating the structure of spicules and producing structures with concentric cylindrical layers can transform a brittle structure into a more flexible one, particularly in load-bearing applications.

Utilizing numerical simulation to determine the reasonable parameters for the design of hydraulic rock-splitting head

The hydraulic rock splitter with a wedge-type splitting head has various advantages, such as simple operation, high work efficiency, safety, shortened work time, and minimal environmental impact. The splitting head driven by a hydraulic cylinder, is the focus of this research, as it directly influences work efficiency. This paper introduces the general structure of the rock splitter machine and the hydraulic cylinder-driven splitting head, along with the method for selecting suitable parameters. To evaluate and select suitable variables, this study establishes procedures and calculation methods for two sets of problems: determining the parameters for the wedge and the parameters for the hydraulic cylinder. The numerical test results provide a design dataset applicable to real-world scenarios, including the wedge angle, cylinder stroke, cylinder diameter, pressure, minimum cylinder wall thickness, and piston rod diameter, corresponding to the respective rock-splitting forces. These parameters meet the set objectives of cylinder pushing force and minimize the cross-sectional area of the cylinder body, contributing to weight reduction and operational convenience.

Multi-objective optimisation of heat transfer and structural strength of aero-piston air-cooled engine cylinder based on orthogonal test

Owing to their compact and lightweight structure, air-cooled aviation piston engines are used in general aviation, agriculture, and military fields. To address the kind of engine thermal load problem, this study used a horizontal four-cylinder four-stroke aviation piston air-cooled gasoline engine as the research object. Tested the engine cylinder temperature and pressure under calibrated power conditions, built a one-dimensional simulation model and a fluid–structure interaction simulation model. Four main structural parameters—fin thickness, fin spacing, fin length, and cylinder wall thickness—were considered as factors. Each factors have five levels to construct orthogonal tests to analyse their influence on the cylinder heat transfer and structural strength performance. A range analysis of the orthogonal test showed that the fin thickness had the most significant influence on the thermal stress, while the fin length most significantly influenced the temperature and cylinder hole deformation. A comprehensive frequency analysis method combining intuitive and range analyses is used to determine the optimal combination scheme, and the heat transfer and strength performance of the engine cylinder before and after optimization is compared. The results indicated that the fin thickness and length had the most influence on cylinder performance. After optimisation, the temperature decreased by 3.3 % from 198.3 ℃ to 191.8 ℃, while the thermal stress decreased by 21.9 % from 100.5 MPa to 78.5 MPa. In addition, the cylinder hole deformation decreased by 11 %, from 0.273 mm to 0.243 mm. These research results can provide a reference for the design and optimisation of heat fins of air-cooled aviation piston engines.

Analytical Formulation to Predict Residual Stresses in Thick-Walled Cylinders Subjected to Hoop Winding, Shrink-Fit, and Conventional and Reverse Autofrettages

Abstract Shrink-fit, wire-winding, and autofrettage processes and their combinations can be effectively used to increase the strength and fatigue life of metallic thick-walled cylinders for a given volume. While several numerical solutions have been developed for determining the residual stress profile through the thickness of thick-walled cylinders for different combinations of the shrink-fit and autofrettage processes, there are no analytical solutions available to predict the residual stress profile induced by the combination of the shrink-fit and inner and outer autofrettage processes with the hoop winding. In this study, the analytical formulations to predict the residual stress distribution for various combinations of the three processes (hoop-winding, shrink-fit, and autofrettage) have been formulated considering the same manufacturing sequences. The results demonstrate that combinations that include the wire-winding process significantly improve the residual stress profile through the wall thickness of single- or two-layer thick-walled cylinders. Specifically, when the wire-winding process is included, the residual stress at the inner surface increases by 25% in single-layer configurations and by 12% in two-layer thick-walled cylinders, respectively, compared to configurations without the wire-winding process.

Modeling of creep-fatigue features of hydrogen storage bed and its parameter optimizing based on finite element method and orthogonal experimental design with artificial neural networks

Regarding the creep-fatigue behavior of hydrogen storage bed (HSB) structures under high-temperature loading and internal pressure loading under repeated hydrogen absorption and desorption process, the heat transfer characteristics and creep-fatigue life during a complete service process in HSB were calculated using Ansys Workbench and Ncode software, and the reliability of the life results calculated by finite element method were validated using ASME code. Based on orthogonal experimental design (OED) theory, an orthogonal experimental table with 4 factors and 5 levels was compiled for the four process parameters: diameter of cooling tube, thickness of cylinder wall, spacing between inner and outer layers, and heat transfer coefficient of condensate. Moreover, an optimization method based on OED coupled with BP ANNs was proposed to find the best process parameters. And the importance of each parameter was analyzed based on range analysis and analysis of variance (ANOVA) to divide the process parameters into rough optimized parameters and precise optimized parameters in this method. In order to identify the optimal process parameter combination of HSB, the maximum life and corresponding process parameter combinations were identified based on OED and the combined method, respectively. The maximum life identified by the combined method proposed in this work is increased by 10.23 % than that identified by OED, which shows the superiority of this combined method.

Parametric Study of Cavity IEMP Responses in a Cylinder by Coupling Monte Carlo Method and 3-D Electromagnetic Particle-in-Cell Method

Internal electromagnetic pulse generated inside a cavity, known as Cavity IEMP, would disturb or damage sensitive electronic systems inside a spacecraft when illuminated by transient X-rays. To ensure their normal operations, accurate prediction and analysis of Cavity IEMP responses are required. In this article, the physical phenomena involved in three-dimensional (3-D) Cavity IEMP problems are numerically studied, including the interaction process between X-rays and the cavity wall material and the self-consistent process involving the motion of electrons and the evolution of electromagnetic fields. The interaction process is simulated with the Monte Carlo method to obtain the actual emission characteristics of forward electrons emitted into a cavity, including their yields, energy, and angular spectra, while the self-consistent process is simulated with a proposed 3-D electromagnetic particle-in-cell method to solve electromagnetic fields generated inside a cavity, whose driving forces are forward electrons with the calculated emission characteristics. This method fully considers electrons with different energies and directions and their impacts on the generated electromagnetic fields. With such method, the electromagnetic field distribution inside a cylinder exposed to transient X-rays is discovered based on the actual emission characteristics of X-ray-induced forward electrons. Furthermore, as forward electron emission characteristics are determined by properties of X-rays and cavities, the impacts of the blackbody temperature in X-ray energy spectrum, the cylinder wall thickness, and the cylinder wall material on the intensity of generated electric fields are fully explored. Based on the results, several suggestions are given to protect electronic systems in cavities against the electromagnetic coupling from Cavity IEMP. The study would guide radiation hardening design of electronic systems in spacecraft.

Неосесимметричная нестационарная задача термоэлектроупругости для длинного пьезокерамического цилиндра

A new closed solution to the uncoupled non-axisymmetric problem of thermoelectroelasticity was constructed for a long hollow piezo-ceramic cylinder for the case of non-stationary temperature alteration on its inner surface, taking into account the convective heat transfer between the outer surface and the environment. Cylindrical surfaces were electroded and connected to a measurement device with large input resistance (idle mode), while the internal surface was grounded. The Fourier—Kirchhoff non-stationary heat conduction equation was considered without taking into account the influence of alteration in the body dimensions and the electric field on the temperature field. The closed solution to the heat conduction problem was constructed by the finite integral transformations (FIT) method. The quasi-static coupled electroelasticity problem at a certain temperature field was solved without taking into account the cylinder inertial properties by the FIT method. The calculated relations obtained made it possible to determine the temperature field, the stress-strain state, as well as the electric field in the long piezo-ceramic cylinder under non-stationary non-axisymmetric action in the form of a function of the temperature alteration. Numerical analysis of the results made it possible to determine the cylinder wall thickness and the region of the temperature effect alteration, where deformation could most efficiently transform into the electrical pulse.

РЕКОМЕНДАЦИИ К ВЫБОРУ ТИПОРАЗМЕРОВ КОРПУСА И УДАРНЫХ ЭЛЕМЕНТОВ ПОМОЛЬНО-СМЕСИТЕЛЬНОГО РОТОРНО-ПУЛЬСАЦИОННОГО КОМПЛЕКСА

In this article, the main recommendations aimed at the optimal choice of body sizes and impact elements of the grinding and mixing rotary pulsation complex, taking into account the power consumption, were analyzed and given. These recommendations were aimed at solving design problems related to determining the dependencies of the size of the housing with its main technological parameters, with the possibility of using data in the design of these complexes. Calculations of a number of basic standard sizes of the complex have been made taking into account the ratios of the diameter and width of the complex, the dimensions of the working elements, their body area, the number of slots based on the following input values, productivity, power consumption and a parameter characterizing the efficiency of the complex – alternating pressure in the channels of the rotor and stator.
 In the work, the power criteria calculated for the turbulent regime were determined. Graphical dependences of the total power costs of the complex on the rotational speed of the stator and rotor elements for a number of basic sizes of the complex are obtained. The housing of the complex was designed taking into account the accepted standard sizes. Taking into account the obtained values of the total power costs for each gap of the complex, the maximum radius of the rotor was determined. Taking into account the conditions of structural strength of the cylinder wall thickness of the complex, calculations were made for the diameters of the stator and rotor for a number of standard sizes of the complex. Based on these calculations, we selected the number of slots on the rotor and stator, their width and height

Numerical Investigation of Conjugate Natural Convection From a Vertical Cylindrical Open Cavity

AbstractAn extensive numerical analysis is performed on a vertical cylindrical open cavity made of aluminum with varying thicknesses to study conjugate natural convection. The key purpose of this study is to evaluate the effect of cylinder wall thickness on natural convection at the outer wall of the cylinder, which is coupled to the inner cylinder wall that has a constant temperature of 450 K and the ambient air which temperature is 300 K. The Navier–Stokes equations, continuity equation, and energy equations are solved numerically. The finite volume method is applied in the computational domain that includes the vertical cylindrical open cavity by using ansys-fluent 18 to specify the properties of flow and exchange of thermal energy. A couple of pertinent parameters are used for the numerical investigation like Rayleigh number within laminar regime (within range 104–108), aspect ratio (undefined proportion of length to diameter of the cylinder (L/D)) of the vertical cylindrical open cavity (2, 4, 6, 8, 10), and cylinder wall thickness (0, 1, 2, 3, 4 mm). This study presents the velocity vector field and thermal plume contours. An approximate Nusselt number to Rayleigh number equation is developed for the vertical cylindrical cavity within the range of Rayleigh numbers addressed by this work.

Magnetic circuit design of MR controller for improving the performance of the suspension

Magnetorheological (MR) damper is widely used in civil engineering, heavy-duty vehicles to speed up safely, and so on. In this paper, an MR controller for adjusting the stiffness and damping of a semi-active air suspension is designed to improve the vibration resistance of the Electric Multiple Units suspension system. The 3D magnetic field simulations of the MR controller are carried out. The influences of factors such as shaft material, damping channel width, cylinder wall thickness on the magnetic induction intensity at the damping channel are studied. An orthogonal experiment is carried out and the optimal combination of the structural parameters is determined. Then, the four working conditions of the MR controller are simulated and analyzed, respectively, and its structure is improved to ensure its stability. Finally, using fluid simulation software analysis, it can be seen that due to the fluidity of magnetorheological fluids (MRFs), the heat generated by the coil has little effect on MRFs.

Composite structure of the magnesium ball valve element for a drilling well

In the oil industry, balls are used in the process of hydraulic fracturing (HF). The material that meets the basic requirements for HF balls is magnesium. Soluble magnesium balls are designed to activate HF couplings. When the coupling seat is reached, during the pumping of HF fluid, the ball temporarily blocks the passage section inside the shank column, which makes it possible to create excess pressure and open the windows of the HF coupling. However, since magnesium has a low density, in drilling fluids with a high density, leaky contact of the ball with the valve seat is possible due to insufficient gravity. This may lead to leakage of the working fluid. The purpose of the work is to create and study a method of manufacturing a ball aimed at weighing it down. The developed method of manufacturing a two-layer ball valve element by stamping is described. The two-layer ball consists of a magnesium shell, inside which a steel ball is placed. A steel ball is placed in a magnesium cylindrical glass with a bottom, the glass is closed with a magnesium lid. The resulting composite assembly is deformed by being compressed with two punches with ends in the form of hemispheres until the ends of the cylindrical cup are tightly closed. As a variant, the shell of the ball is proposed to be made of Mg90 grade magnesium. It is theoretically established that the mass of a bimetallic ball is 2.74 times larger than a magnesium ball. Modeling of stamping of a composite billet is performed in order to establish the possibility of obtaining a ball according to the proposed method. The stress-strain state of a composite billet in the process of shaping is considered. Successful computer simulation of the process gives grounds to recommend the proposed method for implementation in a real experiment. The smallest value of the ratio of the cylinder wall thickness to its height is also established, which ensures the stability of the cylinder wall during deformation.

Influence of the Printing Orientation on Parallelism, Distance, and Wall Thickness of Adjacent Cylinders of 3D-Printed Surgical Guides

This in-vitro study aimed to evaluate the influence of the printing orientation on parallelism, distance, and thickness between adjacent cylinders of 3D-printed surgical guides. CAD software was used to design a surgical guide with two adjacent parallel cylinders (reference); the design was saved as standard tessellation software (STL) and 63 samples were printed using three different orientations (0, 45, and 90 degrees). A metrology digital microscope was used to measure the distance, the angle and the thickness of the guides cylinders. Afterwards, the printed guides were scanned and cloud comparison software was used to compare STL files from the printed guides against the reference CAD model. One-way analysis of variance and Tukey test were used for multiple comparisons between groups and significance was p < 0.05. The printing orientation affected the distance between cylinders, the parallelism and the wall thickness. In addition, there were global deviations in all printing orientations. Printing with 90 degrees orientation produced almost-parallel cylinders but walls thicker than the reference model; all the cylinders converged toward the coronal but printing at 0 degrees produced the closest distance to the reference value. Within the limitations of this experimental in-vitro study it can be concluded that all the printing orientations influence the angle, the distance, and the thickness between adjacent cylinders of a surgical guide. Printing at 90 degrees produces the best global correspondence with the master model.

An efficient, safe, and energy-saving saddle for pressure vessel based on electro-permanent magnet technology

In this paper, a novel magnetic transport saddle based on the electro-permanent magnet (EPM) technology is proposed. A strong and stable magnetic force can be generated by passing only a momentary current during loading and unloading since the magnetic force is provided by the internal permanent magnet, not the electromagnet. The EPM system is convenient to control and has low energy consumption. This research commenced with a preliminary design of the magnetic circuit structure and circuit structure. The feasibility of this magnetic circuit structure is verified by theoretical derivation and magnetic field simulation, and the factors influencing the magnetic force are further investigated. Subsequently, transient thermal analysis was performed for the extreme case of continuous magnetization and demagnetization. Then, a series of experiments such as electrical circuit, magnetic field, and tensile test were performed for the EPM chuck. Based on the magnetic element, the magnetic transport saddle is designed and the magnetic field simulation is performed for the magnetization state. In addition, when the wall thickness of the transport cylinder is too thin and the magnetic force is insufficient, this paper proposes a solution to increase the cushions inside the transported equipment. Finally, the energy-saving performance of the magnetic transport saddle based on the EPM technology is calculated.

Parameter optimization of rubber cylinder of expansion liner hanger based on numerical simulation

The expansion liner hanger has great advantages over the traditional slip liner hanger. Therefore, scholars at home and abroad have carried out extensive research on the expansion liner hanger, but there are few researches on the optimization design of the rubber cylinder of the expansion liner hanger. How to select the size and material of the rubber cylinder is very important to the suspension performance of the expansion liner hanger. Based on the Ø245 mm × Ø178 mm expansion liner hanger as the research object, the condition of the changes under the wall thickness and friction coefficient, using the finite element analysis software of rubber cylinder elongation rate, stress conditions are numerically simulated. The results show that when the wall thickness of the rubber cylinder is t = 1.5 mm, the elongation rate of the rubber cylinder is 2.14 mm, and then the elongation rate of the rubber cylinder increases rapidly with the increase of the wall thickness, and the growth of elongation rate slows down when the wall thickness is t ≥ 3.0 mm. The contact stress of the inner and outer walls of the rubber cylinder increases with the increase of the wall thickness, and the contact stress of the inner wall of the rubber cylinder fluctuates, and the fluctuation tends to be gentle when t ≥ 2.5 mm, and the residual stress of the rubber cylinder is uniformly distributed when t ≥ 2.5 mm. When different friction coefficients (0.05, 0.1, 0.15, 0.2, 0.25, 0.3) were taken between the rubber cylinder and the outer casing, the elongation rate of the rubber cylinder was negatively correlated with the friction coefficient, and the average contact stress on the wall was positively correlated with the friction coefficient. The results of this paper provide guidance for the design and material optimization of the rubber cylinder in the expansion liner hanger.

Modeling and Fatigue Characteristic Analysis of the Gear Flexspline of a Harmonic Reducer

The failure of harmonic gear drive is mainly caused by the fatigue fracture of flexible wheels and the fatigue damage of flexible bearings. In this paper, the stress sensitivity and fatigue life characteristics of flexible wheels with thin-walled vulnerable components are studied. Firstly, the structure of the flexible wheel of a B3-80 general harmonic gear reducer is designed, the finite element model of the flexible wheel is established by using ANSYS finite element software, and the finite element analysis results are compared with the theoretical calculations to verify the correctness of the model. Finally, by changing the cylinder length, smooth cylinder wall thickness and load, the maximum equivalent stress curves of the flexible gear ring, smooth cylinder and flexible wheel bottom are obtained, and the influence law of structural parameters on the stress characteristics of flexible wheel is obtained. At the same time, the influence laws of flexible wheel cylinder length and smooth cylinder wall thickness on the fatigue life of flexible wheel is studied, which provides a theoretical basis for the structural optimization design of the cup flexible wheel.

DEVELOPMENT AND MATERIAL OPTIMIZATION OF 0.67HP PETROL GENERATOR CYLINDER BLOCK USING TAGUCHI DESIGN AND FINITE ELEMENT ANALYSIS

The development of 0.67Hp gasoline generator cylinder block and the material optimization of the component using Taguchi Design and Finite Element Method were carried out successfully. The cylinder block is known to create an avenue for the piston to carry out its reciprocating effect on the crankshaft for onward transmission for the machine output. The designed cylinder block had an engine power of 5.11kw which drove piston through a bore and stroke length of 46.10mm and 51.20mm respectively. The determined clearance volume of 9.46cm 3 was contained in a cylinder wall thickness and block length of 3.04mm and 58.88mm respectively. The designed values were found to be in consonance with recommended values obtained in standard engineering text. The developed mathematical model was determined to be adequate with a statistical Coefficient of determination (R 2 ) of 98.62% and the Adjusted coefficient of determination (Adj R 2 ) was found to be 97.79%. The comparison of optimal values developed from the Taguchi design and genetic algorithm optimizations showed that obtained values from both methods were noticed to be very close as only a difference of about 0.0005 existed among the input parameters. The genetic algorithm result was seen as a kind of validation for the Taguchi design optimization. The Finite element analysis result showed that the temperature output result recorded the highest temperature of 100 o C around the cylinderical bore axis while the lowest temperature of 51.97 o C was found on the cooling fins of the component. Keywords: Optimization, Taguchi Design, Genetic Algorithm and Finite Element Analysis. DOI: 10.7176/JIEA/12-1-04 Publication date: March 31 st 2022

Stress analysis of multi-layered composite cylinders subjected to various loadings

Composite cylinders are widely used in many applications, common examples for these applications are power drive shafts, chemical storage tanks, rocket motor cases and pressure vessels used in aerospace vehicles. The structure of the composite cylinder can be represented as a cylinder composed of coaxial orthotropic layers. In this paper, an analytical method is used to calculate stresses, strains and displacements through the wall thickness of multi-layered composite cylinder made of orthotropic material. The method is based on the theory of elasticity of bodies having cylindrical anisotropy. This method permits accurate stress analysis of thin and thick-walled composite cylinders subjected to axial load, torsional load and bending moment. The analytical method is modified to incorporate internal and external pressure loads beside the prescribed load cases. A numerical example is presented for a composite cylinder subjected to internal pressure load with a tensile axial load. The resulted stresses and strains are used to validate 3-dimensional finite element model. A parametric study has been performed using the analytical method to investigate the influencing parameters on stress distribution within the cylinder thickness and the results are found to be beneficial to look into during the preliminary design phase.

Stress Distribution and Fracture Toughness of Underground Reinforced Plastic Pipe Composite.

Reinforced composite materials have many applications in the aerospace, marine, and petroleum industries. Glass fiber-reinforced pipes are of considerable importance as pressurized vessels, infrastructure materials, and petroleum wastewater pipelines. The stress intensity factor due to through-thickness discontinuities is a major parameter in fracture mechanics to understand the failure mechanisms in glass fiber-composite pipes. The stress intensity factor is calculated for a composite cylinder subjected to internal pressure using the linear extended finite element method based on the law of energy release evaluation of surface damage. The analytical model needs two material properties; they are the tensile strength and the fracture toughness; therefore, a standard tensile test was carried out on a standard specimen taken from the pipe’s wall thickness. Moreover, the compact tension test specimen was manufactured from the pipe’s wall thickness to obtain the fracture toughness. The average tensile strength was measured as 21.5 MPa with a standard deviation of 5.59 MPa, moreover, the average Young’s modulus was measured as 32.75 GPa with a standard deviation of 6.64 GPa. The fracture toughness was measured as 2322 () with a standard deviation of 142.5 (), whereas the average surface release energy () was 153.6 kJ/m2 with a standard deviation of 22.53 kJ/m2. A valuable design equation was extracted from the finite element model to measure the effect of cracks on the hoop stress of the cylinder wall thickness based on a nonlinear model. Moreover, an acceptable equation was used to calculate the correction and shape factor of a cylinder with movable and unmovable through-thickness cracks. This study provides useful tools and guidance for the design and analysis of composite cylinders.

A novel biomimetic design inspired by nested cylindrical structures of spicules

Among the major groups of materials, some polymers and resins are limited in usage due to their brittleness. To date, we lack a comprehensive solution to overcome brittleness. Mimicking from biological structures made up of ceramics with excellent strength and flexibility can help us to find a solution to this problem. In this study, for the first time, we mimicked the structure of spicules in Euplectella aspergillum (EA) sponges and developed a novel structure to improve the mechanical properties of brittle rods. In the newly developed structure, cylinders with various diameters were printed by a 3D printer and then inserted into each other. The nested cylindrical structures (NCSs) with optimized mechanical properties had a cylinder wall thickness of 1.30 mm with a density of 1.27 ± 0.01 g/cm3 (approximately 8.6% less than that of solid rods (SRs)). The flexural strength, strain, modulus and toughness of SR were improved in the NCSs from 108.04 ± 11.30 MPa, 1.95 ± 0.20%, 3.98 ± 0.05 GPa and 1.42 ± 0.20 kJ/m3 to 168.45 ± 14.45 MPa, 4.10 ± 0.41%, 5.52 ± 0.05 GPa and 6.71 ± 0.80 kJ/m3, respectively. The NCSs showed a lower density as well as improved mechanical properties compared to SRs. According to the SEM observations, the dominant mechanisms on the toughening of NCSs with a cylinder wall thickness of 0.80 mm were crack branching, crack bridging, and crack deflection. However, for NCSs with a cylinder wall thickness of 1.00 and 1.30 mm the dominant mechanism was crack deflection. The results of this paper open a new horizon for designing new structures from brittle materials with higher strength and flexibility.

Crack propagation and toughening mechanisms of bio-inspired artificial spicules fabricated by additive manufacturing technique

In this study, for the first time, we produced synthetic spicule-inspired structures (SISs) by 3D printing technology to improve both strength and toughness of brittle rigid resin. The SISs with 0.375 mm cylinder wall thickness without cores showed an improvement of 21%, 1450%, 6000% and 68% in flexural strength, strain, specific toughness and buckling stress (compared to the control samples), respectively. The Shear test results showed that SISs, provide a structure with better dispersing stress. Changing the architecture of solid rods to spiculic structures led to stopping and deflecting the crack path, and subsequently prevented catastrophic failure in these structures. Therefore, SISs can offer a novel and promising approach to increase the strength and flexibility of these brittle materials.