Fiber Stacking Sequence Research Articles

Optimal design of a multilayered piezoelectric transducer based on a special unit cell homogenization method

Piezoelectric transducers with high directional-dependent response are of interest in several applications because of their ability to sense and actuate along specific directions where they can distinguish individual principal strain components. This paper presents an improved unidirectional sensor obtained using a multi-laminate piezocomposite that maximizes the electromechanical coupling factor or the piezoelectric strain constant in one direction with respect to the other directions. Furthermore, multi-laminate structures provide significant design potential by the variation of the orientation and stacking sequence of fibers to obtain the desired properties. The effective properties depend on the number of layers, the fibers orientation as well as the thickness of each layer, and they are estimated by the variational asymptotic method for unit cell homogenization. A design that guarantees maximum directional dependence in terms of piezoelectric strain constant is determined by a global optimization technique using a genetic algorithm. Layered transducers composed of several orthotropic passive layers and a single active layer are considered.

Lock-in thermography for investigation of impact damage in hybrid polypropylene/glass composites

In this contribution, the impact damage modes of a new class of hybrid systems, obtained by the coupling of polypropylene (PP)-based laminates with different interlaminar interface strength and coded as interlaminar-graded interphase strength (IGIS) laminated structures, have been investigated. Several specimens were fabricated by suitably alternating the reinforcement layers with films of the matrix having different intrinsic natures; some specimens were impacted at two energies. All the specimens (impacted or not) have been nondestructively evaluated with lock-in thermography (LT) that is a noncontact, noninvasive technique [10]. The obtained results have been analysed to obtain information on the role played by both the matrix and fibre-stacking sequence on the damage modes, as well as on the overall damage relevance.

Investigation of Thrust Force and Torque Induced Failure on Stacking Sequence of Glass Fibers in GFRP Composite Laminates during Drilling Process

Investigation of Thrust Force and Torque Induced Failure on Stacking Sequence of Glass Fibers in GFRP Composite Laminates during Drilling Process

Crashworthiness of Glass/Polyester Composite Tubular Structures

Advances in automotive and aircraft sectors lead to production of very high speed vehicles. The amount of energy that a vehicle absorbs during collision is a concern to ensure safer and more reliable vehicles. The FRP composite structural members dissipate huge amount of energy during collision and improves the vehicle crashworthiness. Thin walled FRP composite cylindrical shells are used as energy absorbers and absorb large amount of impact energy during collision. The energy absorbing capability of thin walled composite shells is quantified by specific energy absorption (SEA), the energy absorbed per unit mass of crushed material. The SEA of composite shells depends on the way in which the tube material is crushed (axially or laterally). Progressive deformation and stable collapse significantly reduce the forces experienced by the passengers in the event of sudden collision. This paper investigates the influence of fibre orientation and stacking sequence on the SEA of six-ply, 0°/90° Glass/Polyester composite cylindrical shells under axial and lateral compression. The crushing resistance and SEA vary with proportion of axial (0°) and hoop (90°) fibre content and stacking sequence in the tubes. The energy absorption capability under lateral crushing is compared with that of axial compression.

Effect of Fiber Orientation and Stacking Sequence on Mechanical and Thermal Characteristics of Banana-Kenaf Hybrid Epoxy Composite

The usage of hybrid natural composites has surged in almost all fields of engineering due to their advantage of possessing high strength to weight ratio and biodegradability. This paper deals with the fabrication and investigation of mechanical and thermal properties of banana-kenaf glass fiber reinforced epoxy composite which is relatively a newer hybrid composite. In this study, the composite is fabricated by a hand layup process with different fiber orientations and also with different volume fractions. The composites are prepared with five different proportions of banana-kenaf fibers. Various mechanical and thermal tests are conducted and the result shows that the hybrid composite in which fibers are arranged at 450 inclination has better properties than the others. Also, failure morphology analysis is done using a Scanning Electron Microscope (SEM) through which the internal structures of the tested specimen are analysed.

Low-weight Impact Behaviour of Carbon Fibre Reinforced Methyl Methacrylate Nanocomposites

Inthis study, the carbon fibre reinforced methyl methacrylate (CF/MMA) compositetoecap for safety shoes was manufactured to increase the energy absorptioncapacity during impact. Different types of nanofillers such as organic andinorganic nanotubes, unmodified and organically modified nanoclays were appliedto modify matrix impact properties. The drop-weight impact tests of thenanocomposite toecap were performed with respect to nanofiller nature andcarbon fibre stacking sequence. It was found that the most influence on thestiffness and impact damage of the carbon fibre methyl methacrylatenanocomposite toecaps besides stacking sequence show organic and inorganic nanotubesor unmodified nanoclay. DOI: http://dx.doi.org/10.5755/j01.ms.21.2.7075

Multi-objective Optimization of Hybrid Carbon/Glass Fiber Reinforced Epoxy Composite Automotive Drive Shaft

In design and fabricate drive shafts with high value of fundamental natural frequency that represented high value of critical speed; using composite materials instead of typical metallic materials could provide longer length shafts with lighter weight. In this paper, multi-objective optimization (MOP) of a composite drive shaft is performed considering three conflicting objectives: fundamental natural frequency, critical buckling torque and weight of the shaft. Fiber orientation angle, ply thickness and stacking sequence are also considered as the design variables in this MOP. To solve this MOP, Modified Non-Dominated Sorting Genetic Algorithm (modified NSGA II) is employed. To calculate fundamental natural frequency and critical buckling torque, finite element model of a truck composite drive shaft has been carried out using commercial software ABAQUS/Standard. Finally optimum design points are obtained and from all non-dominated optimum design points, some trade-off points are picked using multi-criteria decision analysis methods and the points are discussed.

Role of in-plane stacking sequence on transverse effective thermal conductivity of unidirectional composite laminates

Laminated polymer matrix carbon fiber composites have poor thermal conductivity in through thickness direction as all the conductive fibers are within the plane. One can increase the through thickness thermal conductivity by introducing conductive fibers in that direction or by modifying the form, direction and architecture of the fiber network. In this paper we conduct a parametric study using finite element analysis to investigate the relation between the local fiber architecture and its effective through-thickness thermal conductivity. The role of the fiber tow orientation, volume fraction and stacking sequence is explored. Unidirectional laminates containing fiber tows aligned in the same direction for all laminae exhibit higher through thickness thermal conductivity than the stacking sequence with other orientations. A conductive coating surface layer enhances the thermal conductivity of laminates independent of fiber orientation configuration. A geometric scalar parameter is proposed to correlate laminate through-thickness thermal conductivity with fiber tow stacking sequence. The influence of different boundary condition types on the through-thickness thermal conductivity is also assessed.

Buckling Analysis of thin FRP laminate under Thermal Loading

The present work deals with the prediction of temperature at which buckling starts for a thin FRP laminate using 2-D finite element method that works on classical lamination theory. The problem is modeled in commercial software ANSYS WORKBENCH version 12. Effect of geometrical parameters such as i) Thickness ratio, ii) in-plane aspect ratio, and material parameters such as i) fiber orientation, ii) Fiber stacking sequence on buckling temperature is studied.

The effect of different boundary conditions on crushing behavior of hat-shaped polymer composite energy absorber

Side-door impact b eams are widely used in car doors to improve the passenger’s safety during the side impact. Fiber-reinforced polymer composite materials have a high specific strength and stiffness and are considered suitable candidate for this application. The aim of this study was to investigate energy-absorbing capacity of hat-shaped structures made from fiber-reinforced polymer composite materials at different boundary conditions. A finite element analysis model was developed using ABAQUS/Explicit code to achieve optimized fiber orientation and stacking sequence. Unidirectional E-glass fiber/polyester resin was used to construct hat-shaped beam energy absorber. Finite element analysis has revealed the optimized fiber orientations of [75/0/0/−75], [−75/0/0/75], [60/−30/30/-60], [−75/−30/75/30], [30/60/−30/−60] for quasi-static loadings, and [60/45/−45/−60], [45/−45/−60/60], [75/60/−60/−75], [−30/30/45/−45], [−75/−60/75/60] for impact loadings. Quasi-static bending as well as pendulum type impact test was carried out on specimens made with fiber orientation adopted from numerical analysis. Quasi-static bending test demonstrated that in fully clamped boundary conditions, composite layup orientation of [−75/0/0/75] showed maximum energy-absorbing capacity, but in other boundary conditions, composite layup orientation of [60/−30/30/−60] had the maximum energy-absorbing capacity. Contrarily, pendulum impact test for similar boundary conditions showed the highest energy absorption happened in fiber orientations of [−30/30/45/−45] and [−75/−60/75/60]. It was postulated that different modes of loading were the reason for this discrepancy.

Mechanical Properties of Basalt and Glass Fiber Reinforced Polymer Hybrid Composites

This study describes the mechanical properties of Basalt fiber and Glass fiber reinforced hybrid composites developed by using compression moulding techniques. Woven Basalt fibers and Glass fibers were used for fabricating the hybrid composites, polyester resin as matrix with different fiber stacking sequences. The mechanical properties of hybrid composites like Flexural strength, Impact strength and tensile strength of the various specimens are calculated by using computer assisted Universal testing machine and Charpy Impact testing machine as per the ASTM standards. The result shows that the reinforcement of woven Basalt and Glass fibers hybrid composites significantly influencing on the mechanical properties of the composites and it found that the intermediate properties between basalt glass fibers reinforced composites.

Design Factor Analysis of Fiber Metal Laminates under Concentrated Load by Using Design of Experiment

This research studied quality engineering design of FML (Fiber Metal Laminate) under concentrated load. 1st DOE (Design of Experiment) was conducted to find out vital few Xs. 16 experiments were performed and their results were statistically analyzed. Pareto chart analysis shows that the thickness of fiber prepreg and metal laminate are more important than the material property of fiber prepreg or stacking sequence angle. Also, the stacking sequence of 1st layup prepreg is more important than that of 2nd layup prepreg. The main effect plots shows that the maximum deflection of FML is minimized with increasing layer thickness and modulus of metal laminate. 2nd DOE was conducted to obtain RSM (Response Surface Method) equation. 27 experiments were conducted. The CCD (Central Composite Design) technique with four factors was used. The coefficient of determination (R2) for the calculated RSM equation was 0.97. Optimum design was conducted using the RSM equation. MMFD algorithm was used to optimum design. Optimum values for thickness of prepreg, thickness of metal, modulus of metal, fiber orientation 1 and fiber orientation 2 are 0.135mm, 0.135mm, 80GPa, 0O, 0O, respectively. Quality engineering design was conducted to find out guideline for control range of design parameter. To acquire six sigma level reliability, the standard deviation of design parameter should be controlled within 1% of average design value

Modal Properties of a Cantilevered Laminated Woven Composite Plate as Affected by Stacking Sequence and Fiber Orientation: An Experimental Study

The use of laminated composites in aircraft structures is not totally new. However, the idea of using woven fiber glass as reinforcement in primary structural members is not widely addressed as compared to unidirectional fibers. In an effort to characterize the dynamic behavior of a woven laminated composite subject to dynamic loads, modal testing is performed experimentally on a cantilevered laminated woven glass fiber/epoxy composite flat plate which resembles an aircraft wing with aspect ratio of 5. To that end, the effect of stacking sequence and fiber orientation of the laminated composite plate on the modal properties is assessed. 6-layer laminated composite configurations with various stacking sequence and fiber orientation are fabricated so as to generate variable stiffness plates. The modal test employs the single roving hammer technique to obtain the frequency response of the plate and the results of the first five modes against the fiber orientation and stacking sequence are analyzed.

BONDED JOINTS DESIGN AIDED BY COMPUTATIONAL TOOL DOI 10.5028/jatm.2012.04032912

In order to aid the design of bonded joints, a computational tool named System of Analysis for Joints (SAJ) was developed. The software can analyze single and double lap bonded joint with composite-composite or metal-composite materials as adherent parts. Thus, SAJ can calculate the stress distribution, loads and displacements. Their results were compared to finite element software (ABAQUSTM) and to specific composite analysis software (ESACompTM). After that, a study about the influence of joint design parameters on the mechanical behavior of the bonded joint was carried out. In regards to parametric study, SAJ leads to some conclusions, which can be used as a guide during the product design process. Therefore, aided by the computational tool, it is possible to perform a conceptual and preliminary design of bonded joints with more accuracy and varying many parameters (materials; fiber orientation and stacking sequence of the laminate; thickness; overlap length).

Residual Stress Analysis of Steel Fibre Reinforced Composite Inverted-Tooth Chains

Abstract The aim of this study is to investigate effects on the residual stresses of the fibre orientations and stacking sequences of the inverted-tooth chains which are made of transversely reinforced steel fibre thermoplastic laminated composite materials. For this purpose, fifteen different tooth chain models were created and stress analysis was performed with ANSYS 11.0 finite element program. For each fibre orientation and stacking sequence values of the yield loads where yielding of the inverted-tooth chain just initiates were determined. Then, loads subjected to the inverted-tooth chains were incrementally increased beyond the yield limits to determine plastic and residual stresses that were obtained by removing applied loads from the inverted-tooth chain. As a result of the analysis, it was observed that all values of residual stress components increased depending on the rising applied loads for all fibre orientation as well as for all stacking sequences.

Finite Element Modeling and Analysis of Skin Panel Based On the Fiber Orientation and Stacking Sequence

Composite materials are ideal for structural application where high strength-to-weight and high stiffness-to-weight ratios are required. In particular, Aircraft and Spacecraft are the typical weight-sensitive structures in which composite material are cost-effective. A major purpose of lamination is to tailor the directional dependence of strength and stiffness of a composite material to match the loading environment on the structural element. Since the fiber orientation enables the optimization of the mechanical behavior along a specific direction, the study has been made to analyze the behavior of the laminate properties and strength based on the fiber orientation.

Interlaminar stress analysis for carbon/epoxy composite space rotors

This paper extends the previous works that appears in the International Journal of Multiphysics, Varatharajoo, Salit and Goh (2010). An approach incorporating cohesive zone modelling technique is incorporated into an optimized flywheel to properly simulate the stresses at the layer interfaces. Investigation on several fiber stacking sequences are also conducted to demonstrate the effect of fiber orientations on the overall rotor stress as well as the interface stress behaviour. The results demonstrated that the rotor interlaminar stresses are within the rotor materials' ultimate strength and that the fiber direction with a combination of 45°/-45°/0° offers the best triple layer rotor among the few combinations selected for this analysis. It was shown that the present approach can facilitate also further investigation on the interface stress behaviour of rotating rotors.

Vibration and damping analysis of a composite blade

This paper is concerned with the damping design of a composite propeller blade. A hybrid method is proposed for predicting the structural damping of the composite blade. This method consists of the statistical prediction of high-frequency material damping, the numerical calculation of modal damping, and the conceptual modification of Rayleigh damping. The vibration damping experiment is carried out to investigate the validity of the hybrid method. The effects of fiber orientation angle and stacking sequence on the damping characteristics are investigated. The damped dynamic responses of the composite blade under parametric variations are evaluated. The results show that the dynamic performance of the composite structure can be improved by completing the damping design.

Formation of Resin-Rich Zones in Composites Processing

Resin-rich zones are a common phenomenon in liquid composite molding processes. These resin-rich zones cause unwanted residual stress and deformation, and part-to-part variation, and thus they need to be studied in the design of composite structures. An experimental study on the formation of resin-rich zones in angled composite parts is presented in this paper. Two open-channel mold sets were designed and fabricated. Fiber preforms were loaded into these molds and the gaps formed were visually inspected by a microscope. The influences of corner radius, fiber volume fraction, enclosed angle, and stacking sequence were investigated, and significant factors affecting gap thickness were identified by Design of Experiments (DOE). It can be concluded from the experimental results that: 1) Fiber volume fraction is the most significant factor affecting gap thickness. Gap thickness is inversely proportional to fiber volume fraction; 2) Gap thickness is inversely proportional to radius; 3) The gap thickness of unidirectional preforms is larger than that of the cross-ply preforms.

Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites

In this paper, the damping and dynamic stiffness of UHN125C carbon fiber/epoxy composite beam was experimentally measured. The effect of fiber orientation angle and stacking sequences on damping, resonance frequency, and dynamic stiffness was discussed with a focus on the effect of moisture absorption. Dried specimens were immersed in distilled water for a certain period to absorb water for 8, 16, and 24 d, respectively, and the moisture content absorbed in the specimen was measured. Furthermore, using the impact hammer technique, the measurements of dynamic responses were conducted on a cantilever beam specimen with one end clamped by bolts and metal plates. The damping properties in terms of loss factor were approximated by half-power bandwidth technique. The dynamic stiffness was evaluated using resonance frequency as a function of moisture content. The damping increased with the increase of moisture content; however, the dynamic stiffness reduced with the reduction of resonance frequency. The results of the dynamic stiffness were aided by measuring the dynamic strain using DBU-120A strain-indicating software. The increment in the dynamic strain strengthened the results obtained for dynamic stiffness.