Types Of Laminates Research Articles

Damage prediction of thick composite laminates subjected to low-velocity impact loads

Experimental and numerical studies have been carried out to predict the behavior of composite laminates under low-velocity impact loads. Numerical models were built based on shell elements in order to simulate it efficiently. A strain-based failure theory was employed to predict the damaged area of laminates using a user-defined subroutine. Drop-weight impact tests were performed for verifying the analysis results of the low-velocity impact. The damaged areas were inspected using ultrasonic C-scans, and three types of thick composite laminates were examined. The impactor velocity was measured at time before and after contact with the target. Finally, the proposed numerical model with the failure theory was verified in that it well predicted the impact damage of the three composite laminates chosen for this study.

Investigation on Mechanical and Thermal Properties of a Kenaf/Jute Fiber-Reinforced Polyester Hybrid Biocomposite

This study investigates the mechanical and thermal properties of biocomposite in relation to their hybridization. Compression moulding was utilised to produce hybrid biocomposites composed of polyester resin reinforced with kenaf, jute, and three distinct combinations of kenaf/jute fibers. To increase the bonding of kenaf and jute fibers with polyester resin, a 5 percent NaOH solution was administered to them. The following stacking sequences were used to manufacture a total of five different types of laminates: polyester resin 80 wt%/kenaf fiber 20 wt%, polyester resin 80 wt%/jute fiber 20 wt%), polyester resin 80 wt%/kenaf fiber 5 wt%/jute fiber 15 wt%, polyester resin 80 wt%/kenaf fiber 10 wt%/jute fiber 10 wt%, and polyester resin 80 wt%/kenaf fiber 15 wt%/jute fiber 5 wt%. In the mechanical and thermal tests, it was discovered that the polyester resin 80 wt%/jute fiber 20 wt% biocomposites had increased strength compared to the other hybrid biocomposites investigated.

Ballistic impact experiments of titanium-based carbon-fibre/epoxy laminates

In this paper, high-velocity impact resistance of lightweight laminates with multi-layers of carbon-fibre/epoxy laminates sandwiched by two titanium alloy skins and aluminium alloy skins was extensively investigated by experiments with a total of 48 impact tests conducted. The ballistic limit of the titanium-based carbon-fibre/epoxy laminate was estimated to be between 241.6 m/s and 257.1 m/s. Impact velocity governed energy absorption and the corresponding damage modes were characterised and identified. The influence of fibre metal laminates configuration on the impact resistance was then experimentally investigated at a fixed impact velocity with full penetration in ten types of laminates. The results also showed that thicker skin and higher number of fibre layers favoured the specific energy absorption in the tested matrix.

Structural design of the composite blades for a marine ducted propeller based on a two-way fluid-structure interaction method

Compared to metal materials, fiber-reinforced composites have many advantages such as higher specific strength, higher specific stiffness, lighter weight, better damping performance, and better design ability. By reasonably choosing the material and arranging the stacking sequence, the directional stiffness properties of composite laminates can be tailored to match the actual needs. Hence, the effects of the laminate type on the performance of the composite ducted propeller in both hydrodynamic and structural are analyzed in this paper. The two-way fluid-structure interaction (FSI) method is applied to the composite ducted propeller, whose hydrodynamic performance is compared with the metallic one. The efficiency, deformation, stress, failure and pitch angle properties are compared with different laminate types under various working conditions. Moreover, a parameter optimization method is proposed to obtain the most suitable laminate type for the composite ducted propeller with the optimum hydrodynamic performance and structural properties. The research results can provide references for the design of composite ducted propellers.

Effects of composite material layering on the buckling mode of a cylindrical shell

Introduction. At present, composite materials are widely used in building structures and their components. The relevance of the work is determined by the buckling study of a shell structure made of a carbon fiber reinforced polymer. Despite the available experience in creating geometric models of finite element grids and studying the buckling of shell structures, the task of analyzing the mechanical behavior of shell layers remains insufficiently investigated. Therefore, research into the effects caused by polymer layering variations on a buckling mode appears to be urgent for regulating the layering process at various angle combinations due to a lack of sufficient data.Aim. The study was aimed at identifying a layering pattern, under which maximum and minimum critical forces operate.Materials and methods. The object of the study involves a cylindrical shell with a radius of 300 mm, a height of 600 mm, and a wall thickness of 1.56 mm made of eight variously-oriented carbon fiber layers impregnated with epoxy resin. The design modeling was performed using the finite element method. The cylindrical shell walls were modeled in terms of Laminate type flat elements, taking into account the composite layers. At the lower end, the cylinder was rigidly fixed and 100 kN axial compressive force was applied to the upper end of the cylinder. Using a software package, the variants of buckling modes were obtained for further analysis.Results. The data, describing the buckling of a cylindrical shell, including the critical load coefficient at the first buckling mode were obtained by the finite element method. In addition, the dependence of a critical force on layering patterns was determined. Depending on the critical force value and the buckling mode, the most and least favorable patterns of layering in a package of a composite material were selected.Conclusions. The orientation of layers in a composite material package affects the buckling mode and the value of critical force. An optimal selection of the layer orientation increases the critical force value by 2.25 times based on the information about the conditions of structural loading and fastening.

Composite lay-up configuration effect on double and single sided bonded patch repairs

Understanding the failure modes of damaged or cracked structures and repaired by bonding a composite patch is an essential point to improve its resistance to failure and subsequently extend its service life. In the present study, a 3D finite element analysis using ANSYS software was performed to elucidate the failure modes of the repaired structures by double and single sided bonded composite. The plate is represented by an aluminum plate (Al2024 T3), cracked at the edge and repaired by three types of laminates, with different fiber orientation in order to determine its effect on the repair. The contact interfaces patch-adhesive and aluminum-adhesive were modeled by cohesive zone modeling (CZM) using bilinear interface of delamination (BID) method to determine the failure at the adhesive layer. The obtained results show the importance of the impact of the composite patch fiber orientation on the structure design for suitable repair.

Nuclear mechanoprotection: From tissue atlases as blueprints to distinctive regulation of nuclear lamins.

Two meters of DNA in each of our cells must be protected against many types of damage. Mechanoprotection is increasingly understood to be conferred by the nuclear lamina of intermediate filament proteins, but very different patterns of expression and regulation between different cells and tissues remain a challenge to comprehend and translate into applications. We begin with a tutorial style presentation of “tissue blueprints” of lamin expression including single-cell RNA sequencing in major public datasets. Lamin-A, C profiles appear strikingly similar to those for the mechanosensitive factors Vinculin, Yap1, and Piezo1, whereas datasets for lamin-B1 align with and predict regulation by the cell cycle transcription factor, FOXM1, and further predict poor survival across multiple cancers. Various experiments support the distinction between the lamin types and add mechanistic insight into the mechano-regulation of lamin-A, C by both matrix elasticity and externally imposed tissue strain. Both A- and B-type lamins, nonetheless, protect the nucleus from rupture and damage. Ultimately, for mechanically active tissue constructs and organoids as well as cell therapies, lamin levels require particular attention as they help minimize nuclear damage and defects in a cell cycle.

Research on the mechanical and water-repellent properties of bionic carbon fiber reinforced plastic composites inspired by coelacanth scale and lotus leaf

Carbon fiber reinforced plastic (CFRP) laminates are widely used in vessel side plate, underwater propeller, and submarine oil pipeline because they possess superior specific strength and hydrophobicity compared with metal materials. However, conventional CFRP laminates are limited by insufficient mechanical properties and incompetent water-repellent performance. Herein, a biomimetic double-helicoidal superhydrophobic laminate (BDHSL) was designed and manufactured through a method combining hot press forming and two-step spraying. The BDHSL was composed of double-helicoidal (inspired by coelacanth scale) carbon fiber prepreg and SiO2-based coating with multiscale hierarchical structures (inspired by lotus leaf), which displayed excellent mechanical properties and water-repellency. Besides, mechanical tests were carried out systematically. Remarkably, the peak impact force of the BDHSL at the impact energy of 20 J was 2865.25 N, which increased by 136.88% compared with traditional unidirectional laminate (UL 1209.56 N). Meanwhile, the finite element simulation was conducted using 3D Hashin's failure criteria. The simulation results showed that the predicted stress-deflection curve for four types of laminates correlated well with experimental results. Moreover, the water contact angle of BDHSL reached approximately 156.5°, which indicated its superhydrophobicity. What is more, the durability and water-repellency of the SiO2-based coatings were investigated, which further confirmed its potential underwater applicability. The investigations in this work offer a promising way to effectively design and fabricate exquisitely structured CFRP laminates with hierarchically textured coatings that are more suitable for various marine applications under practical conditions, such as offshore oil drilling platform, autonomous underwater vehicle, high-speed ship, and so forth.

Influence of yarn-hybridisation on the mechanical performance and thermal conductivity of composite laminates

Recently, advanced composite materials have been widely used in numerous applications due to their superior properties. However, their sensitivities to damages during impact loading event limits their usage. In this regards, the influence of yarn hybridisation on the mechanical and thermal performance of composite laminates have been studied using low velocity impact, compression after impact (CAI), flexural and thermal conductivity tests. Two types of composite laminates were manufactured using hybrid yarns (S-glass and polypropylene [PP]) and S-glass yarns through the combination of commingling and core-wrapping methods and converted to non-crimp cross-ply preforms for both laminates. C-scan tests and cross-section microscopy examinations were adopted to identify the damaged areas of impacted laminates and explain the damage failures, which occurred during impact loadings. Results revealed that the hybrid laminates displayed higher damage area reduction compared to glass composites. Although the hybrid composite laminates illustrated considerably lower compressive strength, their residual compressive strength (damage tolerance) was significantly higher than glass composites. Fractography analysis has illustrated that the new damage failure modes such as intra-yarn cracks have been observed in the hybrid yarns laminates. These damage modes have contributed for higher energy absorpsion leading to an enhancement of the damage tolerance of the hybrid laminates. Furthermore, the incorporation of PP fibres resulted in a reduction of thermal conductivity of hybrid laminates compared to pure glass laminates.

Elastic-plastic progressive damage model and low-velocity impact failure mechanism of composite materials

An elastic-plastic progressive damage model (PDM-3DEP) was proposed to study the mechanical response and damage development of composite laminates under low-velocity impact. The 3D Hashin failure criterion and an improved three-dimensional damage evolution model that considers strain component of ε33 and shear stain are implemented to describe the initiation and evolution of damage modes. The zero-thickness cohesive elements which follow bilinear traction-separation law are applied to simulate delamination. The numerical and experimental mechanical curves and damage distribution of composite laminate with a stacking sequence of 03o/45o/−45oS were compared to verify the proposed PDM-3DEP. The consistent results of the numerical and experimental data indicates that the proposed method can accurately describe damage mechanical behavior under low-velocity impact. Moreover, another type of composite laminate with a stacking sequence of 02o/902o/02o/902o/02oS is adopted for further verification. It is concluded that the proposed model can accurately analyze the mechanical responses of different composite laminates.

Comprehensive analysis of expression and prognosis for LMNB family genes in human sarcoma.

Previous studies indicated that lamin proteins were thought to be related to gene expression, chromatin structure, and unclear stability. There are 2 types of vertebrate lamins, including A and B. The 2 B type proteins are encoded by lamin B1 (LMNB1) and lamin B2 (LMNB2). The LMNBs factor has been found to be associated with the development of multiple tumors, but its association with sarcoma has been barely mentioned.The transcription levels of LMNBs were analyzed via Oncomine database. Gene Expression Profiling Interactive Analysis (GEPIA) dataset was adopted to analyze the differential expression of LMNBs in sarcoma. Cancer Cell Line Encyclopedia dataset was used to explore the expression of LMNBs in sarcoma cell line. We analyzed the prognostic value of LMNBs in GEPIA and Kaplan-Meier Plotter. Oncomine and GEPIA datasets were also used to detect the relationship between LMNBs and their co-expressed genes. We used the Database for Annotation, Visualization and Integrated Discovery to conduct the Gene Ontology analysis of LMNBs and their co-expressed genes. Kyoto Encyclopedia of Genes and Genomes was also used to analyze the pathway of LMNBs.LMNB1 and LMNB2 were reported to be hyperexpressed in sarcoma. The expression of LMNBs was elevated in various sarcoma cell lines. According to the results, we observed that LMNBs were connected to the poor overall survival, recurrence-free survival, and disease-free survival of sarcoma patients.This study indicated that hyperexpression of LMNBs was significantly related to worse outcome of sarcoma, LMNB1 and LMNB2 were expected to become potential biomarkers for human.

Automatic void content assessment of composite laminates using a machine-learning approach

Voids have a substantial impact on the mechanical properties of composite laminates and can lead to premature failure of composite parts. Optical microscopy is a commonly employed imaging technique to assess the void content of composite parts, as it is reliable and less expensive than alternative options. Usually, image thresholding techniques are used to parse the void content of the acquired microscopy images automatically; however, these techniques are very sensitive to the imaging acquisition conditions and type of composite material used. Additionally, these algorithms have to be calibrated before each analysis, in order to provide accurate results.This work proposes a machine-learning approach, based on a convolutional neural network architecture, with the objective of providing a robust tool capable of automatically parsing the void content of optical microscopy images, without the need of parameter tuning.Results from training and testing datasets composed of microscopy images extracted from three distinct types of laminates confirm that the proposed approach parses void content from microscopy images more accurately than a traditional thresholding algorithm, without the need of a previous calibration step. This work shows that the proposed approach is promising, despite sometimes lower than expected precision in individual void statistics.

Buckling analysis of multilayer FG-CNT reinforced nanocomposite cylinders assuming CNT waviness, agglomeration, and interphase effects using the CUF-EFG method

In this article, the Carrera unified formulation (CUF) is developed for the buckling analysis of multilayered functionally graded carbon nanotube (MFG-CNT) reinforced cylinders. For this purpose, the CUF is obtained in the cylindrical coordinate system as a first step. Then, the displacement-based CUF is derived from the principle of virtual work in each individual layer in the framework of the element free Galerkin (EFG) method. The mechanical properties of each CNTs-reinforced layer are estimated using the modified Halpin–Tsai (H-T) micromechanical model and rule of mixture. In this model, the waviness, interphase, and agglomeration of CNTs are accounted using influencing factors in terms of CNTs geometric and processing characteristics. Four types of laminates, which are composed of several reinforced layers with different arrangements (distributions) along the radial direction, are taken into account to examine the effect of the layers’ arrangement on the buckling capacity of the cylinder. The proposed CUF-EFG formulations and solution method are validated by comparing the present buckling loads with those obtained by theoretical formula for the homogeneous slender cylinders. A parametric study is conducted to investigate the effects of CNTs weight fraction, waviness, agglomeration and interphase of CNT, distribution of layers, power-law index, radius-to-thickness ratio, length-to-radius ratio, and boundary conditions (BCs) on the critical buckling loads of MFG-CNT reinforced cylinder. The results show the high performance of the proposed CUF-EFG method for buckling analysis of MFG-CNT reinforced cylinders with a wide range of aspect ratios.

WlCount: Geological lamination detection and counting using an image analysis approach

The manual identification and count of laminae in layered textures is a common practice in the study of geological records, which can be time consuming and carry large uncertainty for dense or disturbed lamina textures. We present here a novel image analysis approach to detect and count laminae in geoscientific imagery, called WlCount. Based on Dynamic Time Warping and Wavelet analysis, WlCount firstly aligns persistent vertical elements to increase the continuity of the lamina structure. Then, using a graphical interface, the user extracts the most significant signal frequencies and allows the automatic count of the laminae. The software, tested on a series of stalagmite cut images showing different types of laminations and a tree-ring image, provides an estimation of the laminae detection and count comparable to the manual one. WlCount presents as a useful open-source tool to help geoscientists, sensibly speeding up the lamination count process.

Improving the mechanical performance and impact damage tolerance of glass composite laminates via multi-scales of hybridisation

The glass fabric composite laminates are widely used in the various applications compared to the non-crimp cross-ply laminates due to their high fracture toughness and better impact damage tolerance. However, their in-plane properties are limited owing to the interlacements of their warps and wefts. In this regard, an experimental investigation of the multi-scales hybridisation (i.e. yarns-hybridisation and hybrid layers methods) for improving the mechanical performance, and impact damage tolerance of continuous glass fibre-epoxy composite laminates has been presented. The two types of composite laminates that have intra yarns (i.e. hybrid yarns) and inter-ply (i.e. hybrid layers) with multi-stacking sequence were manufactured via vacuum infusion process and then compared with 2D hybrid fabrics and glass cross-ply composite laminates with respect to in-plane properties and impact damage tolerance respectively. The tensile strength properties and the low-velocity impact response of all laminates were identified by using tensile strength and drop-weight impact tests at different energy levels. The impact damage tolerance was studied by using compression-after-impact (CAI) strength tests, measuring the residual compressive strength of the damaged laminates. The damage characterisation based on impact and compression, and compression after impact was also examined using scanning electronic microscopy (SEM). The outcome of this investigation demonstrated that the intra- and inter-ply hybrid composite laminates showed higher tensile strength and modulus of elasticity, compared to hybrid fabric composites. Moreover, the impact damage tolerances of intra- and inter-ply hybrid laminates were found to be slightly higher than the non-crimp cross-ply glass laminates for certain-impact energy levels.

Vol4 num2-15 Failure prediction in the neighbourhood of the hole in riveted joints with composite materials

In riveted joints, typically two groups of failure mechanisms must be verified, those that affect the joining elements and those that affect the parts that must be drilled to be joined. In this last group, at least, three failure mechanisms must be taken into account: tension, shear and bearing. In each of these failure mechanisms, it must be verified that the component of the stress state responsible for the failure does not exceed a certain critical value that causes the failure. In the case of riveted joints with composite materials, the task is doubly complex. On the one hand, the stress state in the neighbourhood of the hole is complex, not only because of the non-linearity of the problem (the contact of the rivet with the walls of the hole) but also because of the non-isotropic nature of the material. This makes the stresses to have a strong dependence on the type of fiber, stacking sequence, and in general, on the mechanical properties (non-isotropic) of the laminate. On the other hand, the determination of the critical values, associated with each component of the stress state, responsible for each failure mechanism, is difficult to obtain, due to the fact that these strength values also depend on the particular orientation along the hole contour, where they are evaluated. In the present work, the stress state in the neighbourhood of the hole is evaluated in riveted joints with composite materials, analyzing different types of laminates, to serve as a basis for the prediction of the different failure mechanisms potentially acting.

Evaluation of tensile properties of carbon fiber reinforced polymers produced from commercial prepregs

This paper presents the tensile properties of real products produced from prepregs based on the carbon fiber-reinforced polymer (CFRP) composite. In this study, we compared tensile properties of the two types of CFRP laminates with a different number of layers, different type of used carbon fiber woven fabrics, and epoxy resins. Both types are used for production of some interior and exterior parts of the luxury automobiles. This research showed that material No. 1 with DT121HT epoxy resin matrix, which has a higher number of reinforcing layers, is characterized by a higher value of tensile strength. Material No. 2 with DT121R epoxy resin matrix with higher reactivity and higher viscosity, which has a lower number of reinforcing layers, is characterized by a lower value of tensile strength. Reproducibility verification of tensile properties of both chosen materials showed that the CFRP laminates produced from commercial prepregs provide a guarantee of safety of the entire production of the CFRP parts.

Monitoring damage evolution with acoustic emission in two types of glass epoxy laminates

This study concerns the identification and monitoring by acoustic emission (AE) of the different damage mechanisms leading to the final rupture of glass/epoxy laminates. The series of specimens are subjected to static and fatigue loading in order to follow the progression of the various damage mechanisms over time and to identify the most critical ones leading to material failure. The specimens are made with two stacking sequences ([0/90]s and [90/0]s) using the vacuum infusion process. Several parameters such as the energy, the amplitude, the rise-time, the counts and the duration are used for the AE technique in order to identify the damage mechanisms evolutions to classify the collected events (AE). The damage mechanisms recorded in each stacking sequence are identified and characterized using a multi-parametric analysis. The damage accumulated in the test specimen is first of all transverse cracking, followed by interlaminar decohesion and finally fiber breakage leading to total composite failure.

Experimental comparison of Glass and Jute Fiber with & without Eggshell Additive Reinforced Hybrid Composite

The Fiber-Reinforced Composite Is Widely Used Instead Of Traditional Material As It Consists Of Superior Mechanical Properties.An ApplicationOf Fiber-Reinforced Composite Is Defense, Marine, Aircraft, Household Components. In This Paper, An InvestigationWasCarried Out To Compare The Two Types Of Composite Laminate. The First Set Of Composite Laminate Is Made Up Of Jute And Glass Woven Fiber, AndThe Second Composite Laminate Is Made Up Of Jute And Glass Woven Fiber With Eggshell Additive Powder. The Composite Laminate Consists Of 11 Layers. Out Of 11 Layers, 6 Layers Are Glass Fiber And 5 Layers Are Jute Fiber. The Above Two Composites Are Made By Hand Lay Technique And Tested According To Astm Standard. Compare Results Of Two Composite With Eggshell And Without An Eggshell.

Bow structure damage analysis for hybrid coir-glass fiber composite fishing boat hull subjected to front collision load

Abstract Hybridization of natural and synthetic fibers has the ability to improve composite performance. It means that the combination of natural fibers such as coir, jute, bamboo, and sisal with synthetic or glass fiber can broaden the role of the composite material, especially for structural application. This study developed a finite element simulation to investigate the damage to the bow structure of the fishing boat hull, which was produced using hybrid coir-glass fiber composite (HCGFRP) material subjected to front collision load. The experimental measurement was conducted to determine the mechanical properties of four hybrid composite laminates defined based on the differences in their layers number, fiber types, and orientation angle. Moreover, a numerical simulation model was applied to the traditional fishing boat colliding with fishery harbor quay, and the scenario was defined by varying the boat speed and the types of laminates adopted on the hull structure. The results showed the damage level for the bow structure of the HCGFRP boat due to the collision accidents, while the numerical findings are expected to be used as the basic knowledge in applying the hybrid coir-glass fiber laminates composite as an alternative hull construction material.