فهرست مطالب

Mechanics of Advanced Composite Structures - Volume:10 Issue: 2, Summer-Autumn 2023

Mechanics of Advanced Composite Structures
Volume:10 Issue: 2, Summer-Autumn 2023

  • تاریخ انتشار: 1402/08/10
  • تعداد عناوین: 18
  • Reza Nazemnezhad *, Roozbeh Ashrafian Pages 221-232
    To solve a differential equation of motion via more reliable procedures, it is essential to realize their efficiency. Whether Rayleigh's theory can be a compatible platform with two-phase local/nonlocal elasticity to render more reliable results compared to other theories or not is the main question that will be answered by this paper. Thus, nanobeam modeled by Rayleigh beam theory is analyzed by two-phase local/nonlocal elasticity. Governing equation in presence of the axial and transverse displacements is derived by means of Hamilton’s principle and differential law of two-phase elasticity. Next, fourth-order Generalized Differential Quadrature Method (GDQM) is utilized to attain the discretized two-phase formulation. In order to confirm, the method and the results are compared with the exact solution prepared and presented in the literature. Moreover, the effects of various parameters such as geometrical properties like thickness, mode shape number, Local phase fraction coefficient, and nonlocal factor on the natural frequency are investigated to clarify that utilizing these theories with a common goal how ends with more accurate results, and how affects the natural frequencies.
    Keywords: Longitudinal Vibration, Nanobeam, Two-Phase Elasticity
  • Partha Borah, Satadru Kashyap *, Sanjib Banerjee, Sushen Kirtania Pages 233-246
    Pineapple leaf is a natural fibre possessing superior mechanical strength which can be used as a reinforcing component in natural fibre-based composites. In general, composites can endure a wide variety of loads while in service. This work reports the buckling analysis of pineapple fibre reinforced epoxy composites and compared it to an isotropic composite reinforced with a synthetic fibre such as E-glass. The effects of changing the fibre volume fraction and plate aspect ratio, on physical buckling behaviour have been reported. The elastic parameters were calculated analytically, whereas the buckling studies were carried out using the finite element method. Buckling was shown to be significantly influenced by the changes in volume fractions, plate aspect ratio, and buckling mode. Additionally, the influence of design parameters such as optimum ply angle for composite stacking-sequence was also investigated under no shear conditions. It was observed that pineapple leaf fibre composites yielded better buckling characteristics than contemporary synthetic E-glass fibre composites.
    Keywords: Pineapple leaf fibre, E-glass fibre, Buckling Analysis, Finite element modeling
  • Jaber Mirzaei *, Meysam Nouri Niyaraki, Hamidreza Zarei Pages 247-256
    Composite vessels are widely used in industry due to their high strength and low weight. In this research, a composite vessel with a metal liner was designed, manufactured, and subjected to internal pressure. The liner of the tank is made of 304 steel, which is screwed on its main part with two patterns of polar and peripheral twisting. In this research, S-glass fibers and epoxy resin 5052 were used. The vessel was subjected to a pressure of 40 bars. Electric strain gauges were used to measure the strain, and stresses were calculated using Hooke's law. In addition to the experimental method, the vessel was also analyzed numerically. ABAQUS (finite element) software was used to examine the experimental data, and the simulation results showed good consistency with the experimental data. The results of the numerical analysis determined the location of the strain gauges. The results of the two methods were compared and discussed. It was found that at low pressures (pressures lesser than 40 bar), composites do not have a significant role in tolerating vessel stress. It has been observed that changes in the geometry of the structure (the joint of the spherical part and the cylinder) resulted in turbulences in the strain and stress curves near the change site.
    Keywords: Composite Vessel, Internal Pressure, Spherical Cap, Numerical analysis, Experimental Analysis
  • Mohammadreza Eghbali, Seyyed Amirhsoein Hosseini * Pages 257-270
    This paper uses different higher-order shear deformation theories to analyze the axial and transverse dynamic response of carbon nanotube-reinforced composite (CNTRC) beams under moving harmonic load. The governing equations of the CNTRC beam are obtained based on the shear deformation beam theory and the Hamilton principle. The exact solution for dynamic response is presented using the Laplace transform. A comparison of previous studies has been published, where a good agreement is observed. Finally, some examples were used to analyze aspect ratio, other higher-order theories, excitation frequency, the volume fraction of Carbon nanotubes (CNTs), the velocity of a moving harmonic load, and their influence on axial and transverse dynamic and maximum deflections. It was observed that the X-beam is a stronger beam than other CNT patterns, Reddy theory is the lower limit, and HSDT theory is the upper limit. The vibration response and dynamic movement of the structure can be controlled by choosing the appropriate items.
    Keywords: CNTRC beams, Moving harmonic load, Laplace transform, Analytical Solution, Higher-order theories
  • Behrooz Shahriari *, Keyvan Shojaei Pages 271-282
    The correct materials selection in the design of aerospace structures reduces the weight and increases structural efficiency. Since the rotor in gas turbine engines has a significant weight, it is important to reduce its weight. The rotating disks in these rotors are subjected to mechanical and thermal loads and experience high-temperature gradients and angular velocities. This work aims to analyze the stress of a rotating disk made of carbon-carbon (C/C) composite to withstand mechanical and thermal loads and reduce the weight of the rotor. The behavior of constant thickness C/C composite disks is studied based on the Tsai-Wu Failure Theory. To do so, first, the basic properties of the material, disk size, rotation speed, temperature distribution, and other requirements are determined. The differential governing equations are obtained by assuming the plane stress state, Hooke's law, and compatibility condition, and the stresses, strains, and displacements are obtained. Considering the safety factors of 1 and 1.5, the critical velocities are calculated using the Tsai-Wu failure theory. Finally, according to the information obtained from the analysis, the evaluation of disks with different layers is compared with other similar disks made with different materials.
    Keywords: Axial Compressor, Rotating Disk, Carbon-Carbon Composite, Mechanical Stress, Thermal Stress
  • Mohsen Azizi, Ali Choopanian Benis, Mehdi Vaezi, Majid Jamal-Omidi * Pages 283-294
    Composite sandwich structures are vastly utilized in the transportation and aerospace industries as highly effective energy absorbers. This paper aims to study a comparative study on the role of the composite corrugated sheet as a core in sandwich panels under low-velocity loading conditions. In this regard, three types of sandwich structures with different corrugated cores, including three unit cells that have identical mass and mechanical properties, are designed and manufactured. The material system utilized for the face skins and core is woven E-glass/epoxy. Corrugated cores are fabricated using specially designed molds and press techniques and afterward bonded to face sheets for the production of corrugated sandwich panels. In the following, by performing the compression tests on corrugated sandwich panels, the impact response, failure modes, and energy absorption ability for different core shapes are explored. The results reveal that the sandwich panels with the rectangular core have a higher capacity in load carrying and energy absorption than the triangular and arc-shaped cores. It is found that the composite sandwich panels with a rectangular profile increased by 1.14 and 3 times in the SEA compared to the other two types of profiles. It is also observed that the initial mode of failure in these core geometries is buckling of cell walls, and continued loading leads to the fracture of the cell walls (fiber breaking), delamination, and debonding between face sheets and core. The present results provide valuable information on corrugated configurations in the design of sandwich structures and engineering applications.
    Keywords: sandwich panel, Corrugated core, Glass, epoxy, Quasi-static impact, energy absorption
  • Khaled Kharrati *, Madiha Salhi, Jemaa Sliman, Ridha Abdeljabar Pages 295-308
    The main objective of this experimental study is to valorize local materials in order to use them as composite Materials (CM) for construction. In this study case, the CM is composed of fibers of Luffa sponge embedded in plaster. Although material resources are abundant in Tunisian territories, their use is very limited. Plaster, the by-product of heat treatment of gypsum, is used in building as coatings and decorative elements. Despite its satisfactory isolation, it has a weakness in its mechanical strength. In this research study, we focus on the enhancement of the thermo-mechanical properties of plaster by adding Luffa sponge fibers into its Matrix. The experimental studies rely on varying the mass fractions of Luffa sponge fibers chemically treated by an alkaline solution (NaOH) in the plaster matrix and then testing thermo-mechanical and physical properties. The results showed that an adequate optimum compromise linking all properties (mechanical, thermal, and chemical) is reached by CM made up of 1% Luffa sponge fibers for the following condition of chemical treatment of 1% NaOH at a temperature of 50°C for 90 min.
    Keywords: Luffa sponge fibers, reinforced plaster, mechanical characteristics, thermo-physical properties
  • Mahsa Soheil Shamaee *, AhmadReza Ghasemi Pages 309-318

    Grid-stiffened composite shells are one of the most important structures in many industries. These structures based on their fabrication method, provide both high strength and light structural weight. In this study, buckling analysis under external hydrostatic pressure is performed to obtain critical buckling pressure and the optimum values of parameters for stiffeners. First-order shear deformation theory (FSDT) based on the Ritz method is used to calculate the critical buckling load of these structures. The effects of shell thickness, angle of helical stiffeners, rib section area, and the stiffeners number into the buckling load are determined. Comparing the calculated buckling load for stiffened and non-stiffened structures shows that stiffeners significantly optimize structural performance. Furthermore, optimization of stiffener parameters is done by Genetic Algorithm. The results show that the introduced structure has the minimum mass. So, the stiffener parameters would be better. According to the results, the optimum dimensions for stiffener buckling load for the optimal stiffener have been increased by about 80% compared to non-stiffened.

    Keywords: Grid Stiffeners, Buckling load, Composite Shell, Optimization, Genetic algorithm
  • Masoumeh Soltani * Pages 319-332
    This paper intends to introduce a new and simple technique to precisely assess the axial instability of a shear deformable sandwich nanobeam. The section of the considered beam element is composed of two metal face layers and an axially functionally graded (AFG) core. The power volume fraction law is utilized to describe the properties of spatially graded materials of the core. The coupled governing differential equations in terms of transverse displacement and angle of rotation due to bending are extracted within the context of first-order shear deformation theory and Eringen’s nonlocal elasticity model. The resulting equilibrium equations are then combined and transformed into a unique fifth-order differential equation. Then, the numerical differential quadrature technique is used to estimate the endurable axial critical loads. The most beneficial feature of the proposed technique is to simplify and decrease the essential computational efforts to obtain the endurable axial buckling loads of sandwich shear-deformable nano-scale beams with AFG core. In the case of an axially loaded Timoshenko nanobeam subjected to simply supported end conditions, the obtained results are compared with those accessible in the literature to confirm the correctness and reliability of the proposed approach. Eventually, comprehensive parameterization research is performed to investigate the sensitivity of linear buckling resistance to slenderness ratio, nonlocal parameter, volume fraction exponent, and thickness ratio. The numerical outcomes indicate obviously that the stability strength of sandwich Timoshenko nanobeam is significantly affected by these parameters.
    Keywords: Sandwich nanobeam, Functionally graded core, Nonlocal parameter, Buckling, First-order shear deformation theory
  • Majid Safarabadi *, Mehran Shahryari, Amin Montazeri, Amin Mohammadi Barkchay Pages 333-342
    In the aerospace industry, the usage of sandwich panels in a variety of space structures such as satellites is increasing due to their excellent features like high strength-to-weight ratio, and thermal insulation. These structures are subjected to a variety of thermal loads depending on their working conditions, which cause them to expand or contract. Since these panels are connected simultaneously by twists, buckling is possible due to thermal loads. In this paper, the thermal buckling analysis of a CCCC Aluminum honeycomb core sandwich panel is performed under asymmetric thermal loading, using ABAQUS. The face sheets are attached to the core by adhesive. Thermal loading is assumed to be two heat fluxes of 70 watts and 20 watts, which are asymmetric, and face sheets radiate heat to their surroundings. The modeling results showed the panel does not buckle under the mentioned thermal loading. The critical buckling stress is 750 MPa and 400 MPa where the maximum thermal stress is 95 MPa and 37 MPa for vertical and horizontal edges respectively, which shows a significant difference of 8 to 11 times. The temperature distribution of the various points of the panel was also obtained by calculating the maximum temperature of 84 °C at the 70-watt heat flux location and the minimum temperature of 15.65 °C in the lower-left corner. The influence of various parameters like face sheets and core cell wall thickness on buckling occurrence is also discussed.
    Keywords: sandwich panel, Thermal buckling, Finite element analysis, Composites
  • Sandeep Pendhari *, S. Harwande, Sharawari Kulkarni, Tanmay Vora, Jainil Visariya Pages 343-362
    A simple semi-analytical approach is used in the present studies to achieve a thermal response of composite and sandwich layered materials in stresses and displacements. Three-dimensional (3D) heat conduction formulation has been formulated as a boundary value problem (BVP) to obtain accurate through-thickness temperature variation, which is further used for thermal stress analysis. Four layered domains of composite and/or sandwich laminate with variable degrees of orthotropic and several transverse and in-plane aspect ratios have been used for numerical investigation. Exact solutions from past studies have been used for comparison with the outcomes received in the present study and proved the accuracy and efficiency of current developments. Additionally, simple constant and linear through-thickness temperature variation has been considered for stress analysis to highlight the importance and need for exact temperature distribution for thermal stress analysis of composite and sandwich laminates. The presented semi-analytical approach achieves the benefit of exact analysis and numerical analysis and leads to accuracy and computational efficiency.
    Keywords: Composites, Laminate, BVP, PDE, ode
  • Meera Saheb Koppanati *, Mukkala Naga Rani, K Krishna Bhaskar Pages 363-374
    Graphene has become a significant and handy nanomaterial due to its excellent tensile strength, electrical conductivity, and stiffness, and is the thinnest material. It could be utilized to reinforce the polymer matrix of composites, increasing their strength and stiffness. In this study, the vibration behaviour of carbon fiber graphene-reinforced hybrid polymer plate, graphene-reinforced polymer plate, and carbon fiber-reinforced polymer plate (CFRP), is examined in the context of developing laminated composite plates. The material properties of the graphene-reinforced matrix are estimated using the applicable Halpin-Tsai models. Following that, the orthotropic mechanical properties of a composite carbon fiber and hybrid matrix lamina are evaluated. Plates are modeled using finite element modeling methods while taking into account a specific stacking order and geometric layouts. The impact hammer modal testing method is used to document the plates' reaction to vibration. In order to see the intrinsic frequencies and mode shapes of the plate, the recorded time domain responses are translated to the frequency domain using the Fast Fourier transform (FFT). The ME Scope software is used for post-processing. The modes of vibration response are assessed by applying various boundary conditions. Results indicate that natural frequencies increase with increasing graphene volume fraction. The larger the volume percentage, the higher the plate’s frequency for all transverse modes, as seen. By incorporating 1% graphene into the polymer matrix, the first, second, third, and fourth mode forms increase by up to 32.35%, 48.96%, 22.17%, and 30.08%, respectively. Adding graphene to the composite raises the frequency of higher modes relative to the basic mode.
    Keywords: Halpin- Tsai Model, finite element method, Stacking sequence, Experimental modal analysis, Fast Fourier Transform
  • Vishwas Mahesh * Pages 375-382
    Natural fiber composites are increasingly replacing synthetic fibers in today's world due to their numerous benefits. The current study focuses on the production and characterization of hybrid composites incorporating jute/bamboo fibers with a variety of stacking sequences created by the hand layup process. Tensile, flexural, impact, and interlaminar shear strength, Shore D hardness, flammability, and water absorption qualities of manufactured stacking sequences were all examined. Thermogravimetric Analysis (TGA) was used to examine the thermal characteristics of the produced composites. The tensile-fractured surface was studied using a scanning electron microscope (SEM). The obtained results revealed that the tensile, impact and flexural strength of the hybridized composite Bamboo/Jute/Jute/Bamboo (BJJB) was better compared to its counterparts. The hybridization of the composites proved beneficial against impact resistance compared to non-hybridized composites. The flammability of the Jute/Jute/Jute/Jute (JJJJ) composite and the thermal stability of the Bamboo/Bamboo/Bamboo/Bamboo (BBBB) composite is found to be better compared to its counterparts. The fracture mechanism involved in the proposed composites is studied with the help of SEM images. The proposed composites are found to be suitable for light load conditions of automobiles and building equipment.
    Keywords: Jute, Bamboo, Thermo-mechanical characterization, Sustainable composite, Light load automobile applications
  • Jigyasa Singh, Ram Prasad * Pages 383-392
    This paper presents the free vibration and buckling responses of a skew sandwich plate using higher-order shear deformation theory (HSDT).  The governing differential equations (GDEs) for the skew sandwich plate are obtained using Hamilton's principle, which states that the actual motion of a system minimizes the total potential energy of the system. The GDEs obtained are discretized using radial basis function (RBF), which is a meshfree based numerical method. The vibration and buckling results for skew sandwich plates using meshfree methods and the effect of node distribution are not available in the open literature to the best of the author's knowledge. Numerous results are presented showing the non-dimensional frequency and buckling parameters of the skew sandwich plates for different values of the plate geometry, material properties, and boundary conditions. These results provide insights into the vibration and buckling behavior of skew sandwich plates and can be used to optimize the design and performance of these plates for various applications, such as aerospace structures, marine structures, and civil engineering structures. Convergence studies of present results are checked, and the results obtained are also validated with the results available in the open literature. The effect of span-to-thickness ratio, core-to-face thickness ratio, aspect ratio, boundary conditions, boundary node distribution, and skew angle is examined. The results presented in this paper can be useful for engineers and researchers working in the field of structural mechanics and can contribute to the development of safer and more efficient structures.
    Keywords: Skew plate, HSDT, Sandwich, Meshfree, vibration, Buckling
  • Pappula Bridjesh *, Narayanan Kannaiyan Geetha, G. Chandra Mohana Reddy Pages 393-406
    In functionally graded materials (FGM), pores have a key impact. A variety of properties, such as resistance to mechanical shock, thermal insulation, catalytic efficiency, and the release of thermal stress, can be added by gradually changing pores distribution from the inner surface to the exterior surface. Tensile strength and the material's Young's modulus are impacted by the level and distribution of porosity. Two directional functionally graded beams are subjected to different sets of boundary conditions by employing a fifth-order shear deformation theory. The power-law distribution shows that the material properties of the beam change in both axial and thickness directions. Axial and transverse cross-sectional deflections are given in polynomial forms in order to calculate the critical buckling load. The auxiliary functions are combined with the displacement functions to fulfill the boundary criteria. Considerations for the boundary conditions include the following three: Clamped - clamped (CC), Simply supported (SS), and Clamped-free (CF). The computed findings are contrasted with earlier attempts in order to aid in the convergence and verification investigations. The effects of different aspect ratios, boundary conditions, and gradient indices on the buckling responses of the two directional functionally graded beams are all investigated.
    Keywords: Functionally graded beam, Higher Order Shear Deformation Theory, Buckling, Porous FGB
  • Ali Khalili, Abdolvahed Kami *, Vahid Abedini Pages 407-418
    Fused deposition modeling is one of the most common methods of additive manufacturing that has enabled the 3D printing of composites. Compared with traditional procedures, this method reduces part cost and production time. This paper investigated the effects of layer height, print speed, and nozzle temperature on the tensile and flexural characteristics of polylactic acid/continuous carbon fiber (PLA/CCF) composite. Two predicting models were developed based on the mechanical tests' data to estimate composite specimens' tensile and flexural strength. These models were used in a two-objective optimization procedure to obtain the composite's highest tensile and flexural strength. The optimum layer thickness, print speed, and nozzle temperature values were 0.3 mm, 4 mm/s, and 200°C, respectively. Adjusting the optimal values of the study parameters increased tensile and flexural strength by 77 and 27.5 percent, respectively, over the unreinforced sample. Furthermore, the fracture section of the composite was examined by scanning electron microscopy (SEM). The SEM images showed that the printing parameters influenced fiber impregnation, which in turn affected the sample's strength. Finally, two composite samples were successfully 3D printed with higher complexity using the optimized values of the studied parameters.
    Keywords: Additive Manufacturing, Fused Deposition Modeling, Polymer matrix composites, Carbon fiber, Continuous Fiber Composites
  • Yajuvindra Kumar *, Imran Ali Pages 419-436
    In this paper, free transverse vibration and buckling analyses of a nanobeam are presented by coupling the Euler-Bernoulli beam (EBT) theory and Eringen’s nonlocal elasticity theory. The nanobeam is embedded in the Pasternak foundation. Hamilton’s energy principle is used to derive governing differential equations. The Lagrange polynomial-based differential quadrature method (PDQM) and a harmonic differential quadrature method (HDQM) are used to convert the governing differential equation and boundary conditions into a set of linear algebraic equations. The first three frequencies and the lowest critical buckling loads for clamped-clamped, clamped-simply supported, and simply supported-simply supported boundary conditions are obtained by implementing the bisection method through a computer program written in C++. The impacts of nonlocal Eringen’s parameter (scaling effect parameter), boundary conditions, axial force, and elastic foundation moduli on frequencies are examined. The effects of nonlocal Eringen’s parameter, boundary conditions, and elastic foundation moduli on critical buckling load are also studied. A convergence study of both versions of DQM is conducted to validate the present analysis. A comparison of frequencies and critical buckling loads with those available in the literature is presented.
    Keywords: Free vibration, Buckling, Nonlocal, Nanobeam, Euler-Bernoulli beam theory, Pasternak foundation, PDQM, HDQM
  • Azita Shafaee Fallah, Mostafa Sadeghian, MohammadEsmaiel Golmakani * Pages 437-448

    Considering the old methods of maintenance and repair of oil and gas pipelines such as welding or replacing a part of the damaged pipeline which include high costs and spending a lot of time, the important usage of novel methods with lower costs such as the use of composite patches can be highlighted. In this research, the strength of steel cracked pipe with composite patches of glass fibers and epoxy/polyester resins has been studied experimentally. A crack with a length of 15 mm in the longitudinal axis of the pipe is considered. The specimen was subjected to internal pressure by a hydraulic pump to evaluate the strength of the glass/epoxy and glass/polyester composite patches considering the effects of fiber distributions, fiber angles, number of layers, and dimensions. Also, a comparison has been made between glass/polyester composites in two modes of complete curing and initial curing. Finally, the experimental test results were compared with the numerical simulations obtained by Abaqus software and the accuracy and precision of the study were verified. Some of the obtained results indicate that arrangement and number of layers have significant roles in the pressure-bearing capacity of composite patches. In this paper, for the first time, the effect of composite patches with different fiber orientations and the number of layers as well as curing effects are considered for the cracked pipe. The results show that the pressure-bearing capacity of composite patches rises with increasing the number of composite layers. Also, it can be seen that after complete curing of the glass-polyester composites, the pressure-bearing capacity rises about 3 times in 3- and 5-layer composites, and in 7-layer ones, it increases about 2 times.

    Keywords: Repaired steel pipe, Composite patch, Hydrostatic test, Experimental Study, Numerical simulation