High Damage Tolerance Research Articles

Mechanical and thermal properties as a function of matrix composition of all-oxide ceramic matrix composites fabricated by a sequential infiltration process

The microstructural design of matrices for all-oxide ceramic matrix composites (Ox/Ox) with damage tolerant fracture behavior is challenging. Therefore, the potential use of different matrix materials might be limited even though they appear to offer advantageous functional properties, such as thermal insulation or corrosion resistance. In this study, we investigated the hypothesis of simultaneously adjusting mechanical and functional properties by separate matrix phases within and between the fiber bundles in Ox/Ox. A sequential infiltration process was used to manufacture Ox/Ox with an alumina-zirconia matrix phase (high damage tolerance) and a mullite-alumina matrix phase (thermal insulation). The effect on the mechanical and thermal properties was governed by the infiltration sequences. A property combination was achieved for either the mechanical or the thermal behavior. This was due to a shear-induced mixing of the matrix phases during the lamination process, which renders it difficult to achieve distinctly separated matrix phases within the composite.

Tailored directional porosity in ceramic matrix composites (CMCs) for hypersonic applications

AbstractIn the field of hypersonic systems and their missions, the occurring flows impose extreme mechanical and thermal loads on the materials used. At the German Aerospace Center (DLR), extensive research is conducted in this area, ranging from design and specification to the development of suitable materials concluding with the proof of concept under realistic conditions in wind tunnels. In recent years, ceramic matrix composites (CMCs) have been investigated for specific aspects of hypersonics. These materials exhibit consistent mechanical behavior over a wide temperature range (up to 1600 °C), coupled with high damage tolerance and thermal shock resistance, distinguishing them from metals and superalloys. Particularly, special porous C/C–SiC ceramics (carbon-fiber-reinforced carbon with silicon carbide) enable innovative material applications for components in transpiration cooling, fuel injection, or boundary-layer transition control. The work presented focuses on the next generation of porous C/C–SiC ceramics currently in development. By deliberately modifying the textile preform, the resulting microstructure and pore morphology are influenced, allowing for control over both the total volume and the orientation of the pores. Relevant parameters influencing porosity have been determined based on the results, and an initial characterization has been conducted. It has been demonstrated that there is a preferred direction of porosity within the sample thickness (Z-axis), and in terms of hypersonic-relevant properties, an absorption coefficient of 0.58 for an acoustic wave at 500 kHz (static pressure of 15 kPa), as well as a length-specific flow resistance of 3.4 MPa s/m2 and an overall porosity of 12.25% were determined. Building upon these promising initial findings, the goal is to further expand the understanding of the parameters influencing porosity and to generate a tailored material for different application scenarios by correlating them with hypersonic properties.

Synthesis and evaluation of thermal and optical properites of Fe2AlB2 phase alloy for thermal control in space applications

Ternary laminated Fe2AlB2 alloy holds its significance in displaying high strength, damage tolerance, oxidation and radiation cracking resistance. It is synthesized through a pressureless sintering route from elemental powders. Synthesis of Fe2AlB2 is studied from two different molar ratios (2/1/2 and 2/1.5/2) and three different sintering temperatures (1100°C, 1150 °C and 1200 °C). Phase analysis is carried out through an x-ray diffractometer and scanning electron microscopy (SEM). In addition, thermal decomposition, thermal conductivity and absorbance spectra are examined. Fe2AlB2 begins to decompose at 1169 °C into borides and aluminides. Thermal conductivity and diffusivity of Fe2AlB2 decreases with increase in temperature. Lower solar reflectivity and high thermal emittance of Fe2AlB2 implies the thermal control and optical behavior that can be expected for extreme space environments.

Corrosion protective properties on 2024‐T3 of chitosan‐modified montmorillonite epoxy coatings based on Ce3+ loading

Abstract2024 aluminum alloy has high strength, processing performance, and good damage tolerance performance, but it is prone to intergranular corrosion and pitting. Therefore, the development of corrosion protective coatings is essential for the aluminum alloy. In this paper, cerium ion (Ce3+) was doped into chitosan‐modified montmorillonite (Ce‐CS‐MMT) by ion exchange method, and the corrosion protective performance of Ce‐CS‐MMT epoxy coating (Ce‐CS‐MMT/EP) was investigated. The electrochemical analysis of aluminum alloy in cerium‐containing solution showed the corrosion inhibition efficiency reached 95.52%. The result indicates the corrosion inhibition effect of cerium‐containing solution was better than pure NaCl solution and MMT solution. The corrosion study of the coating illustrates that the protection rate of Ce‐CS‐MMT/EP reached 95.82%, which was higher than that 91.83% of Ce‐MMT/EP. The result indicates the resistance of charge transfer was greater and the better shielding effect for electrolyte corrosion ions than MMT and Ce‐MMT epoxy coatings, and the corrosion protective performance was excellent.

Compressive Failure Characteristics of 3D Four-Directional Braided Composites with Prefabricated Holes.

The low delamination tendency and high damage tolerance of three-dimensional (3D) braided composites highlight their significant potential in handling defects. To enhance the engineering potential of three-dimensional four-directional (3D4d) braided composites and assess the failure mode of hole defects, this study introduces a series of 3D4d braided composites with prefabricated holes, studying their compressive properties and failure mechanisms through experimental and finite element methods. Digital image correlation (DIC) was used to monitor the compressive strain on the surface of materials. Scanning acoustic microscope (SAM) and scanning electron microscopy (SEM) were used to characterize the longitudinal compression failure mode inside the material. A macroscopic model is established, and the porous materials are predicted by using the general braided composite material prediction theory. While reducing the forecast cost, the error is also controlled within 21%. The analysis of failure mechanisms elucidates the damage extension mode, and the porous damage tolerance ability aligns closely with the bearing mode of braided material structure. Different braiding angles will lead to different bearing modes of materials. Under longitudinal compression, the average strength loss of 15° specimens is 38.21%, and that of 30° specimens is 8.1%. The larger the braided angle, the stronger the porous damage tolerance. Different types of prefabricated holes will also affect their mechanical properties and damage tolerance.

Bending performance and failure mechanism of CFRP/Al hat-shaped thin-walled hybrid beams

Hat-shaped beams played an important role in the body load-bearing structure, such as B-pillar. Fiber metal laminates possessed great advantages of excellent stiffness/strength, high damage tolerance and lightweight effect. In order to improve the catastrophic damage mode of carbon fiber, the hat-shape thin-walled hybrid beams consisting of carbon fiber reinforced thermoplastic (CFRP) prepreg and aluminum (Al) sheet were proposed and fabricated by hot-pressing molding. The effects of carbon fiber layer numbers, CFRP/Al stacking sequence, and the CFRP layup orientation on the three-point bending performance and failure mode of the hat-shaped hybrid beams were investigated. The results showed that the more CFRP layer, the better the bending performance of the hybrid hat-shaped beams. The CA-2 hat-shaped beams generated overall lateral deformation. The ACA (Al/CFRP/Al) hat-shaped beams achieved a higher CFE (ratio of average load to peak force) value and better energy absorption effect. The deformation processes of AC (Al/CFRP) and ACA stacking structures was similar, the horizontal web concave and the side walls on both sides convex. In terms of fiber lay-up orientation, ACA-OR (orthogonal) possessed superior bending performance and energy absorption to the ACA-UD (unidirectional) hybrid beams. Furthermore, the failure mechanism of the ACA hybrid beams was analyzed and the cross-sectional microstructure at different sections were observed by SEM. Matrix cracking, interfacial delamination, fiber fracture and metal plastic deformation were detected, which played a supporting effect and energy absorption role.

Fatigue deformation behavior and fracture mechanism of high fatigue-resistant laser directed energy deposition fabricated titanium alloy: Effect of multi-scale microstructure

The application of the laser directed energy deposition (LDED) titanium (Ti) alloys has been severely impeded by their poor low cycle fatigue (LCF) properties in aerospace industry. Herein, we propose to improve the LCF properties of LDED-ed Ti6Al4V alloys via microstructure adjustment. A solid solution aging 850AA treatment is made to regulate the microstructure into a multi-scale composition dominated by discontinuous αGB and coarsened αP+(αS+β) phases. The LCF properties of LDED-ed Ti6Al4V with a multi-scale microstructure even outperform the wrought Ti6Al4V at high strain amplitudes. Furthermore, this multi-scale microstructure has special local plastic deformation behavior and dislocation activities under cyclic stress loading, which strongly affects the internal stress evolution and crack propagation. The fatigue softening behavior is attributed to the combined effect of back stress and friction stress. Fatigue cracks are deflected by the α/β boundary when the angle (φ) between the long axis of α lamellae and the crack direction is less than 35°. The transgranular fracture occurs when φ is close to 90° (70°–90°). Meanwhile, the fatigue crack usually propagates along the basal or prismatic planes with high Schmid factors. These findings provide novel insights into the microstructure design of LDED-ed Ti alloys with high fatigue damage tolerance.

Design and additive manufacturing of bionic hybrid structure inspired by cuttlebone to achieve superior mechanical properties and shape memory function

Lightweight porous materials with high load-bearing, damage tolerance and energy absorption (EA) as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications, e.g. aerospace, automobiles, electronics, etc. Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient, enabling stress homogenization, significant load bearing, and damage tolerance to protect the organism from high external pressures in the deep sea. This work illustrated that the complex hybrid wave shape in cuttlebone walls, becoming more tortuous from bottom to top, creates a lightweight, load-bearing structure with progressive failure. By mimicking the cuttlebone, a novel bionic hybrid structure (BHS) was proposed, and as a comparison, a regular corrugated structure and a straight wall structure were designed. Three types of designed structures have been successfully manufactured by laser powder bed fusion (LPBF) with NiTi powder. The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4 μm. Microstructural analysis indicated that the LPBF-processed BHS had a strong (001) crystallographic orientation and an average size of 9.85 μm. Mechanical analysis revealed the LPBF-processed BHS could withstand over 25 000 times its weight without significant deformation and had the highest specific EA value (5.32 J·g−1) due to the absence of stress concentration and progressive wall failure during compression. Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity. Importantly, the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated (over 99% recovery rate). These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.

Research on foldable two-matrix 3D braided composites: Manufacturing and bending progressive damage

Research on foldable two-matrix 3D braided composites: Manufacturing and bending progressive damage

Enhanced 3D printing and crack control in melt-grown eutectic ceramic composites with high-entropy alloy doping

As a 3D printing method, laser powder bed fusion (LPBF) technology has been extensively proven to offer significant advantages in fabricating complex structured specimens, achieving ultra-fine microstructures, and enhancing performances. In the domain of manufacturing melt-grown oxide ceramics, it encounters substantial challenges in suppressing crack defects during the rapid solidification process. The strategic integration of high entropy alloys (HEA), leveraging the significant ductility and toughness into ceramic powders represents a major innovation in overcoming the obstacles. The ingenious doping of HEA particles preserves the eutectic microstructures of the Al2O3/GdAlO3(GAP)/ZrO2 ceramic composite. The high damage tolerance of the HEA alloy under high strain rates enables the absorption of crack energy and alleviation of internal stresses during LPBF, effectively reducing crack initiation and growth. Due to increased curvature forces and intense Marangoni convection at the top of the molt pool, particle collision intensifies, leading to the tendency of HEA particles to agglomerate at the upper part of the molt pool. However, this phenomenon can be effectively alleviated in the remelting process of subsequent layer deposition. Furthermore, a portion of the HEA particles partially dissolves and sinks into the molten pool, acting as heterogeneous nucleation particles, inducing the formation of equiaxed eutectic and leading primary phase nucleation. Some HEA particles diffuse into the lamellar ternary eutectic structures, further promoting the refinement of eutectic microstructures due to increased undercooling. The innovative doping of HEA particles has effectively facilitated the fabrication of turbine-structured, conical, and cylindrical ternary eutectic ceramic composite specimens with diameters of about 70 mm, demonstrating significant developmental potential in the field of ceramic composite manufacturing.

Impact response characteristics and damage mechanism of continuous carbon-fiber-reinforced magnesium matrix composite materials

The continuous carbon-fiber-reinforced magnesium matrix composite (C_f/Mg) is a new type of composite material made of a magnesium alloy sheet and carbon-fiber-reinforced composite material with alternating layers. It has the advantages of high damage tolerance, light weight, and corrosion resistance, and has become the first choice of lightweight materials in aerospace, transportation, and other fields. Because impact-resistance serves as an important index for its structural design and performance stability, a continuous carbon-fiber-reinforced magnesium matrix composite with indirect bonding using a modified epoxy resin was designed in this study. Moreover, C_f/Mg was chosen to be the object of research through the selection of constituent materials such as magnesium alloys, carbon fibers, resins, and other properties, which matched the aim of realizing a lightweight material. With the help of hot-compression molding technology, dynamic impact mechanical behavior, and damage analysis technology, the structural design and preparation process optimization of epoxy resin carbon-fiber prepregs and magnesium alloy layer materials, as well as the dynamic impact mechanical response characteristics and damage evolution process under different impact energy conditions, were studied. Accordingly, through a combination of low-velocity impact experiments and numerical simulations, the effects of continuous multiple impacts at the same location with the same impact energy, as well as impacts with the same impact energy and different punch diameters, on the low-velocity impact damage behavior and dynamic impact response characteristics of C_f/Mg were investigated. The results of this study show that when the 5J impact is applied four times consecutively, the peak impact load gradually increases with the increasing number of impacts. Moreover, the peak impact loads of the second, third, and fourth impacts increase by 6.09%, 10.7%, and 14.5%, respectively, compared with the results of the first impact.

Theoretical study on the influence of grain size on the strength, toughness and plastic deformation mechanism of pre-cracked polycrystalline high entropy alloys

High entropy alloys (HEAs) is a kind of structural material with excellent mechanical properties. The material exhibits excellent damage tolerance at low temperature, which is closely related to its potential crack tip plastic mechanism and overall fracture mode. In the research, the plastic deformation and fracture mechanical properties of polycrystalline CrMnFeCoNi HEAs with pre-crack under type I tensile load were investigated by molecular dynamics (MD) simulation. The effects of grain size and crack length on the strength, toughness and microstructural deformation of the alloy were analyzed. It is found that with the increase of grain size, the strength of the material increases and the toughness decreases. With the increase of crack length, the strength and toughness decrease, and the influence of grain size on the strength is weakened. The plastic mechanism of crack initiation in nanocrystalline HEAs is ductile cracking under the joint action of dislocations, amorphization and grain boundary plasticity, which provides high damage tolerance. As the grain size increases, additional cavities appear near the crack tip or at the grain boundary, resulting in brittle fracture mode along the grain boundary or at the end of the cavity, which greatly affects the plastic properties of the material. The initial crack length has a significant effect on the transformation of the fracture mode. With the increase of the initial crack size, the critical grain size of the brittle fracture mode increases, and its proportion in the whole fracture mode decreases. This study provides a theoretical reference for the design and application of nanocrystalline HEAs.

Synthesis, crystal structure and properties of YB2C2

ABSTRACT YB2C2 is a novel ultra-high temperature ceramic material with high damage tolerance. In this work, the synthesis mechanism, crystal structure, electronic structure, elastic properties and thermal shock resistance of YB2C2 were systematically investigated through experiments and calculations. It was determined by differential scanning calorimetry with the heating rate of 10°C/min that YB2C2 was formed by the reaction of YB2C and C at about 1202°C, and became the main phase at 1450°C. The space group of YB2C2 was determined to be P4/mbm by X-ray diffraction, transmission electron microscopy, Rietveld refinement and first-principles calculations for the first time. The lattice constants are a = b = 0.5351 nm and c = 0.3561 nm. The atom positions are as follows: Y is located at 2a (0, 0, 0), B is located 4 h (0.133, 0.633, 0.5) and C is located at 4 h (0.662, 0.162, 0.5). The chemical bonding of YB2C2 displayed sharp anisotropy, with strong B-C bond within the B2C2 nets, and weak Y-B/Y-C bond between Y atom layers and B2C2 nets. Additionally, YB2C2 exhibited abnormal thermal shock resistance when the thermal shock temperature exceeded 800°C, with the residual flexural strength at 1300°C being more than 70% of the strength at room temperature.

A review of modification methods, joints and self-healing methods of adhesive for aerospace.

In recent years, the adhesive technology has been widely used in the production of high-strength joins and precise positioning of various materials, such as metals, glass and composite materials. The adhesive technology has become a promising assembly process in the aerospace field due to its versatility, low creep and high damage tolerance. However, the reliability and predictability of adhesive bonding still require further development due to the complex operating conditions involved. Therefore, this article reviews and discusses the latest advances in aerospace adhesive technology, such as methods for improving bonding performance, bonding techniques (including joints structure and failure modes) and self-healing adhesive layers. Additionally, the current research results are summarised, and possible development trends and research directions in the field of adhesive bonding are prospected.

Enhancing structural resilience by using 3D printed complex polymer reinforcement for high damage tolerant structures

Conventional cementitious structures demonstrate high compressive strength, yet they are inherently prone to brittleness. The development of materials or building blocks with high damage tolerance is essential for constructing robust buildings and structures, capable of withstanding various forms of damage. In this study, we introduce a novel approach that involves incorporating 3D printed complex schwarzites and zeolite based biodegradable polymer porous structures (soft phase) as a reinforcement medium within cement matrices (brittle phase). In the case of composite using primitive schwarzites and primitive gyroids, the specific resilience increases by 128.1% and 121.30%, respectively, compared to the control 3D printed structures. The most remarkable enhancement was observed in zeolites based structures, where the specific resilience was improved by 125.63% w.r.t the cement cube and an 505.33% compared to the control pristine 3D printed structure, respectively. This transformation effectively would mitigate the inherent brittleness of cement blocks, imparting a more ductile and damage-tolerant charecteristic to the composite material. These findings highlight the superior resilient structure and energy absorption capabilities of the composite blocks with different 3D printed polymer structures compared to pure cement cubes.

Fiber Synergy of Polyvinyl Alcohol and Steel Fibers on the Bond Behavior of a Hybrid Fiber-Reinforced Cementitious Composite.

Based on multi-scale characteristics inherent in the cracking process of cementitious composites, fibers with different geometric dimensions are simultaneously used to restrain the formation and development of cracks at different scales. Accordingly, hybrid fiber-reinforced cementitious composites (HyFRCCs) exhibit excellent bond behavior and deformation capacity in terms of tension and compression, accompanied by higher damage tolerance. Using these benefits of the mechanical properties of HyFRCCs, the structural performance of HyFRCC structures under complex loading conditions can be improved. To objectively evaluate the contributions of all fibers to the mechanical properties of HyFRCCs, steel macro-fibers, and polyvinyl alcohol (PVA) micro-fibers were used to design several reinforced cementitious composites. Four of the specimens were mono-fibrous cementitious composites, three specimens were cementitious composites reinforced with hybrid fibers, and one was a non-fibrous cementitious composite. The synergy effect of the steel and PVA fibers was analyzed using various fiber combinations. The results indicated a significant enhancement of the bonding properties of HyFRCCs through the incorporation of PVA and steel fibers. Specifically, the peak bond strength, peak slip displacement, and residual bond strength exhibited increments ranging from 31.0% to 41.7%, 60.6% to 118.4%, and 34.6% to 391.3%, respectively, in comparison to the reference test block. Notably, the combined presence of the PVA and steel fibers consistently demonstrated a positive confounding effect on the residual bond strength. However, negative confounding effects were observed in terms of the peak bond strength and peak slip displacement, particularly with 1.0% steel fiber content and 0.5% PVA fiber content.

First-principles investigations of Fe-based A3BX ceramics with high stiffness and damage tolerance.

In the search for high-stiffness and damage-tolerant materials, Fe-based A3BX carbide and nitride anti-perovskites were studied using first-principles calculations. These perovskites were found to be stable in cubic structures, as substantiated by the formation energy, elastic Born stability criterion, and phonon dispersion spectrum analysis. The GGA functional was applied for geometry optimization, and the lattice constants are found to be 3.730 Å, 3.715 Å, 3.832 Å, and 3.828 Å for Fe3AlC, Fe3AlN, Fe3SnC, and Fe3SnN, respectively. Elastic property analysis reveals that all the materials have large elastic moduli, high sound velocities, and high Debye temperatures. Among them, carbides have superior stiffness and quasi-ductile properties, and they can be further improved by applying additional pressure. Preliminary analysis of electronic properties indicates that they are ferromagnetic and metallic compounds. Their high melting temperatures (>2600 K) confirm their potential in high-temperature applications. The lowest thermal conductivity of Fe3SnN suggests its potential in efficient solid-state refrigeration application. Moreover, Fe3SnC is proposed to be a viable damage-tolerant material with good prospects. Under 10 GPa external pressure, it possesses a ductile structure with a Young's modulus of 402.15 GPa and bulk modulus of 280.25 GPa.

A comprehensive first-principles insights into the physical properties of binary intermetallic Zr3Ir compound

We have looked into the structural, mechanical, optoelectronic, superconducting state and thermophysical aspects of intermetallic compound Zr3Ir using the density functional theory (DFT). Many of the physical properties, including detailed direction dependent mechanical properties, hardness in different formalisms, Fermi surface topology, machinability, fracture toughness, optical properties, chemical bonding nature, and charge density distributions, are being investigated for the first time. According to this study, Zr3Ir exhibits ductile features, high machinability, significant metallic bonding, a small Vickers hardness with low Debye temperature, and a modest level of elastic anisotropy. Ductility, high level of machinability, and damage tolerance make this compound attractive for engineering applications. The mechanical and dynamical stabilities of Zr3Ir have been confirmed. The metallic nature of Zr3Ir is seen in the electronic band structures with a high electronic energy density of states at the Fermi level. The bonding nature has been explored by the charge density mapping and bond population analysis. Zr3Ir shows a remarkable electronic stability, as confirmed by the presence of a pseudogap in the electronic energy density of states at the Fermi level which is situated between the bonding and antibonding states. Energy dependent optical parameters show very good agreement with the electronic density of states profile. The reflectivity spectra reveal that Zr3Ir is a good reflector in the infrared and near-visible regions. Zr3Ir is an excellent ultra-violet (UV) radiation absorber. High refractive index at visible photon energies indicates that Zr3Ir could be used to improve the visual aspects of electronic displays. All the optical constants exhibit a moderate degree of anisotropy. Zr3Ir has a moderate melting point, high damage tolerance, and very low minimum thermal conductivity. The thermomechanical characteristics of Zr3Ir reveal that it is a potential thermal barrier coating material. The superconducting state parameters of Zr3Ir are also explored.

Enhanced tribological performance of nanotwinned copper enabled by sliding-induced heterostructure

Nanotwinned metals have many advantages such as high strength, reasonable ductility and high damage tolerance. However, studies on their tribological properties are scarce, especially the tribological performance relative to the counterparts with comparable hardness. Here, dry sliding tests of electrodeposited nanotwinned copper sample (NT-Cu) are carried out in comparison with the nanocrystalline copper (NC-Cu) and coarse-grained brass (CG-Br) samples that have similar initial hardness. Their worn surface morphologies, chemical compositions and worn subsurface microstructures are characterized in detail. At a load of 3 N, the friction coefficient of NT-Cu is 0.25, which is 44 % and 58 % lower than CG-Br and NC-Cu, respectively. The wear rate is 1.4×10−6(mm−3/Nm), which is 3.8 % of NC-Cu and 10.4 % of CG-Br, respectively. When the load is increased to 5 N, their difference in wear rate increases obviously. The superior tribological performance of NT-Cu is attributed to the sliding-induced layered heterostructure that can effectively accommodate frictional work and suppress the cracking and peeling-off of dynamic recrystallized structures.

Fibre stacking sequence and mechanical characterization of polymer hybrid composites: An experimental study

With rapid development in the field of polymer-reinforced composites, the trend has shifted towards hybridization. Natural fibres have been found to have poor water resistance and synthetic fibres like glass fibres are hybridized to enhance the mechanical strength of individual fibres. In this regard, carbon fibre has good strength but poor damage tolerance, whereas kevlar fibre has a high strain capacity and good damage tolerance. Glass fibres have high toughness and are less expensive. Meanwhile, basalt fibre is cheaper than carbon fibre and stronger than glass fibre. To obtain optimized results of costs and superior mechanical properties, these fibres can be blended into hybrid laminates. This research work involves examining the significance of hybridization and as well as the stacking sequence of fibre-reinforced composites. The hand layup method was implemented to produce five different types of composite laminates containing ten layers each. The micro structural analysis of the fracture surface was conducted. The study revealed that the stacking sequence plays a tremendous role in enhancing the strength of polymer composites. From the test results, it was found that sample A exhibited tensile load of 15428 N, impact strength of 5.8 J and flexural strength of 677 N which was maximum compared with other samples B, C, D and E. It was found that the hybrids produced with kevlar and carbon fibres as the outer layer exhibited a significant effect on the overall composite laminate and showed more tensile, flexural, impact strength, and hardness.