Impact Fracture Mechanism Research Articles

FEM, DEM and FDEM applications on impact fracture of glass and laminated glass – A revie

Structural glass components are prevalently used in engineering. Due to the brittle nature, glass or laminated glass may fracture during an impact action, and the flying fragments may spread over a wide range, resulting in human injuries and asset losses. In this article, the authors aimed at providing a comprehensive review concerning the numerical applications on the impact fracture of glass and laminated glass. Relevant numerical applications employing the finite element method (FEM), discrete element method (DEM) and combined finite-discrete element method (FDEM) were reviewed, and features of the simulations were summarised. Insights into the accuracy, efficiency, ease of implementation and range of applicability were also provided. This review is meant for the rapid and beneficial understanding towards the impact fracture mechanism of glass and laminated glass.

Analysis of the dynamic impact behavior and fracture mechanism of coal samples at various temperatures

A thorough understanding of the mechanical properties and fracture mechanisms of coal under high-temperature conditions is crucial for preventing deep coal and rock dynamic disasters. Utilizing the Hopkinson pressure bar experimental system, this study conducts an in-depth analysis of the strength characteristics, failure modes, microscopic properties, and energy consumption effects of coal between 0 and 250℃. The findings reveal that during the heating process, coal’s mass loss increases with temperature, but at a decreasing rate. Significant changes in the coal samples’ dynamic strength, fragmentation, microscopic features, energy evolution, and fracture mechanisms occur at 100℃, marking a turning point in their dynamic behavior. Both dynamic strength and elastic modulus experience a transient increase at 100℃, while the fractal dimension experiences a brief decrease. At 100℃, the thermal expansion of coal particles predominates over the thermal damage from high temperatures, resulting in an increase in the coal samples’ dynamic strength. As the temperature further rises, thermal damage to the coal samples intensifies, leading to a decrease in dynamic strength. Similarly, the absorption and dissipation energy index K of the coal samples experiences a brief increase at 100℃, signifying a sudden change in the energy evolution pattern. Observations of the coal samples’ failure modes upon impact reveal a transition from tensile failure to a combined shear-tensile failure with increasing temperature.

Impact fracture failure analysis and mechanism study of a TBM disc cutter ring

The fracture of the disc cutting ring significantly impedes the efficiency of TBM. This phenomenon is particularly obvious in geological conditions with high impact loads, such as fracture zones and extremely hard rock areas. In these environments, the incidence of disc cutter ring fracture failure escalates dramatically. To explore the impact fracture failure causes and mechanisms of the disc cutter ring under high impact loads, and to guide the improvement of cutter ring manufacturing process, an in-depth analysis was conducted. The chemical composition, tensile strength, hardness, impact toughness, structure morphology and impact specimen fracture morphology of the cutter ring from a TBM project were measured and analyzed. The results show that the tensile strength point of the disc cutter ring coincides with the fracture point, demonstrating that the ring has an extremely strong brittleness. The impact toughness of the surface of the disc cutter ring is lower than that of the inside, and cracks are easy to start on the surface of the disc cutter ring. According to the microstructure analysis, there are coarse Al-rich inclusions precipitated between grains, accompanied by microcracks and microvoids, which reduce the mechanical properties of the disc cutter ring. Through the fracture morphology analysis, the type of the disc cutter ring impact fracture is a mixture of quasi-cleavage, cleavage and intergranular. When a very high impact load is applied, cracks first nucleate at hard points such as coarse carbides, Al-rich inclusions and voids, and then the main crack propagates in a tortuous manner parallel to the force direction.

Dynamic mechanical response and failure characteristics of coal and rock under saltwater immersion conditions

The stability of coal and rock masses in water-rich mines is affected by both mine water erosion and dynamic disturbances. Thus, it is necessary to study the dynamic mechanical response and failure characteristics of coal and rock under the combination of saltwater and a high strain rate. To this end, a split Hopkinson pressure bar device was employed to investigate the effects of impact velocity, water content, and immersion liquid on the dynamic mechanical behaviours of coal and rock. The results revealed that the weakening effect of saltwater on the dynamic mechanical properties of coal and rock is much greater than that of distilled water. With increasing moisture content, the dynamic compressive strength of the coal specimens decreases monotonically, while that of the rock shows a trend of first increasing and then decreasing. The failure process and destruction of coal and rock are comprehensively affected by both the external impact load and the physical and mechanical properties of the material. The degree of damage of the coal and rock specimens increases with increasing impact velocity and water content. Moreover, the influence of various factors on the impact fracture mechanism of coal and rock under saltwater immersion conditions was revealed. These findings are highly important for the design and maintenance of underground coal and rock building structures.

Comparison of the Mechanical Properties of Hardfacings Made by Standard Coated Stick Electrodes and a Newly Developed Rectangular Stick Electrode.

Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilution rate at the same time-a new type of electrode was developed, exhibiting a rectangular cross-section instead of a round one. Hardfacings, welded with E Fe8 electrodes according to EN 14 700 Standard were welded on mild steel S355 J2 base material with three different coated stick electrodes. The first one was a commercially available, standard, round hardfacing electrode, the second was the same, but with a thinner coating, and the third one was a newly developed rectangular electrode. All three types had equal cross-sections of the metallic core and the same type of coating. Manufacturing of the rectangular electrodes in the laboratory is explained briefly. One- and multi-layer deposits were welded with all three types. Differences were observed in the arc behavior between the round and rectangular electrodes. With the rectangular electrode, the microstructure of the deposit was finer, penetration was shallower, and dilution rates were lower, while the hardness was higher, residual stresses predominantly compressive, and the results of instrumented Charpy impact tests and fracture mechanics tests were better.

Experimental and numerical investigation of impact behavior in honeycomb sandwich composites

This paper presents an experimental and numerical study on the low-energy impact fatigue and bending behavior of sandwich panels reinforced with composite laminate glass and carbon fabric facesheets, supported by a honeycomb core made of Nomex. The crushing behavior of honeycomb sandwich specimens subjected to the impact test was compared and discussed. Our results indicate that the carbon composite facesheets have a significant effect on the impact, resulting in an increase in impact resistance and a 157.14% increase in crack depth in the elastic region compared to glass facesheets reinforcement. This increase serves as an indicator of the laminate's ability to resist damage initiation and impact fracture mechanisms. Also, an increasing in flexural strength about 45.72% was observed in carbon facesheets honeycomb specimens compared to glass facesheets reinforcement. Microscopic illustration of the damaged honeycomb sandwich specimens was conducted to evaluate the interfacial characteristics and describe the damage mechanics of the composite facesheets and core adhesion under the impact test. The numerical approach proves to be efficient in terms of accuracy and simplicity compared to existing methods for predicting the damage mechanisms of honeycomb sandwich structures. It was noted that results of numerical study show best agreements with experiment results and the model can be used to predict the low-energy impact fatigue.

Failure mechanism of 6252-armor steel under hypervelocity impact by 93W alloy projectile

In this study, we analyzed the fracture mechanism of the 6252-armor steel target exposed to the impact of a kinetic energy projectile made of 93W alloy. By examining the impact pressure, crater morphology, and fracture mechanism at various impact velocities, we established the relationship among these factors. As the impact velocity increased, the ratio of penetration depth to crater diameter initially increased, then stabilized, and ultimately approached 0.7 when impact pressures exceeded 49.78 GPa. For impact pressures below 70.71 GPa, macroscopic cracks were predominantly observed on the side of the crater, with no macroscopic cracks found at the bottom. However, if the pressure exceeded 70.71 GPa, the majority of macroscopic cracks occurred at the bottom of the crater. We also found a decrease in spacing between cracks or shear bands and the recrystallized grain size at the interface when the impact velocity increased. Notably, the fracture patterns demonstrated a mixture of brittle and ductile failure modes simultaneously.

Effect of microstructure on impact fracture mechanism of a high-strength Ti-5Al-7.5V-0.5Si-0.25Fe-0.2O alloy

The impact property of high-strength Ti-5Al-7.5V-0.5Si-0.25Fe-0.2O alloy (Ti575) with trimodal microstructure (TM) and lamellar microstructure (LM) were investigated by combining instrumented Charpy U-notch impact test with microstructure characterization. Impact load-displacement curves illustrated that the higher impact toughness of LM (47.8 J/cm2) than TM (38 J/cm2) were attributed to both intrinsic toughening during crack initiation and extrinsic toughening during crack propagation. In crack initiation stage of LM, electron back-scattered diffraction (EBSD) evidenced the nucleation of numerous {10–12} <–1011> tensile twins in coarsened lamellar α (αl) in vicinity of the crack notch. The high intrinsic toughness of LM was due to the dynamic microstructure refinement and facilitation of prismatic/pyramidal slip induced by twins during impact. For TM in contrast, smaller-sized primary α(αp) and αl suppressed the nucleation of twins, exacerbated stress concentration and reduced plastic deformation near the crack notch. In crack propagation stage, the kinking, shearing of αl, crack deflection at αl/β interfaces and secondary crack in αl colony borders contributed to a tortuous crack path and large energy dissipation in LM, whereas crack could bypass αp and cut through thin αl in TM easily, resulting in a flat crack path and poor extrinsic toughness of TM. In summary, this work provided a basic understanding of the impact fracture mechanism of Ti575 with different microstructures.

Toughening of polypropylene by elastomer‐coated brominated polystyrene

AbstractBrominated polystyrene (BPS) is an effective additive for improving fire retardancy of polymers. However, BPS reduces impact strength due to its brittleness and poor compatibility with most polymer matrices. The present study aims at using BPS both as a flame retardant and as a toughening agent to improve polymer properties. Specifically, styrene‐ethylene‐butylene‐styrene (SEBS) elastomer was chosen as a compatibilizer to control dispersion and particle size of BPS in polypropylene (PP). By choosing appropriate type and amount of SEBS and proper processing parameters, it is found that both impact fracture toughness and fire retardancy of PP can be greatly enhanced. The impact fracture mechanisms responsible for the observed toughening effect is investigated. The usefulness of the above study for the preparation of multifunctional fire‐retardant particles for enhancing polymer properties is also discussed.

Numerical and experimental investigation of impact strength and fracture mechanism of Kevlar and Hemp elastomeric thin biocomposite laminate under high-velocity impact: A comparative study

Thin composite structures reinforced with woven fabrics are widely used in many industrial sectors due to their lightweight, easy access, and high specific performance. Due to safety, the study of fracture mechanisms and energy absorption of thin composite structures is significant. In this study, Kevlar and Hemp elastomeric thin biocomposite laminates with an elastomeric matrix filled with natural lignin filler with a low carbon footprint and with the aim of the sustainability concept of environmental protection have been designed experimentally and numerically for testing under high-velocity impact. The impact resistance of elastomeric composites reinforced with natural fillers is less reported. Good interaction of lignin-filled elastomeric matrix with woven hemp fabric is expected to show impact performance comparable to Kevlar-reinforced composites. For this purpose, Kevlar and hemp thin elastomeric biocomposites are tested under high-velocity impact with almost the same surface density. Also, tensile and dynamic compression tests (Hopkinson test) were performed to check the mechanical properties of the elastomer layer. The proposed laminates' penetration resistance and fracture behavior during an impact according to the Kevlar and hemp fabric constituent material model and the user-defined material model (VUMAT) for the nonlinear behavior of elastomeric materials considering the damage criterion in ABAQUS/Explicit confirmed. The results show, In the thin elastomeric hemp biocomposites, the tensile failure and stress transfer to the surrounding bundles cause more yarns to participate in the load-carrying process. As a result, the low penetration depth and more significant protection margin in fully green hemp composites provide impact performance comparable to Kevlar elastomeric composites.

Influence of laser surface treatment on the microstructure distribution, bearing capacity and impact property of 1.0C‐1.5Cr steel

A diode laser with a rectangular spot was used to perform laser surface treatment on a 1.0C‐1.5Cr steel. Based on the numerical simulation, an empirical equation was developed to predict the peak temperature, and the microstructure distribution was analyzed. The bearing capacity and impact fracture mechanisms were also studied. The results indicated that the relationship between the peak temperature and scanning rate was affected by the depth, and the peak temperature on the outer surface was approximately linear with the reciprocal of the square root of the scanning rate. The higher peak temperature leads to cementite dissolution and coarsening near the outer surface. Cementite dissolution was postponed during the laser surface treatment. The bearing capacity was a combined result of strengthening in the surface region and softening in the heat affect zone. Under a lighter contact load, laser surface treatment had no adverse effect on the bearing capacity. However, under a heavier contact load, the plastic deformation of the heat affect zone slightly decreased the bearing capacity. The impact fracture started at the outer surface of the laser-hardened layer, and propagated intergranularly near the crack source, and then propagated inward through the transgranular fracture. Owing to the stress concentration near the interface between the cementite and martensite matrix, cementite particles tend to appear along the crack propagation path. The decrease in the impact absorbed energy is attributed to the brittleness of the hardened layer and tensile residual stress, and the impact toughness can be improved by preheating.

Impact strength and fracture behavior of Halloysite nanotube (HNT)-modified carbon fiber-reinforced polymers (CFRPs) based on the electrophoretic dispersion (EPD) process

Because particles that accumulate without movement can lead to a deposition gradient, the formation of a stable suspension is essential for the electrophoretic dispersion (EPD) process. The hydrophobic properties of Halloysite nanotubes (HNTs) were easily dispersed in many nonpolar polymers without further deformation steps. However, the uniform dispersion of HNTs in aqueous solutions is a pre-EPD process task. The zeta potential controls the main parameters of EPD processes, such as the density of deposits, particle orientation and velocity, and repulsive interactions between particles, which determine the stability of the suspension. In this study, the solution stability range for the addition of nanoparticles was measured and the optimal dispersion range was determined. In addition, an HNT-reinforced composite material was created by determining the optimal dispersion stability range of HNT, and the impact strength and fracture mechanism of the interface were analyzed. The solution stability and dispersion were the best between pH 6.6 and 6.8, and the highest impact strength was confirmed at 0.7 wt%. The HNT confirmed the interfacial dispersion of the EPD-fibers using scanning electron microscopy and dispersive X-ray spectroscopy (SEM-EDS).

Impact toughness and fractography of diverse microstructure in Al-Cu alloy fabricated by arc-directed energy deposition

To investigate the effects of heterogeneous microstructure, precipitates, and pore defects on dynamic impact toughness of Al-Cu alloy fabricated by arc-directed energy deposition (Arc-DED). Samples with diverse microstructures were prepared by adjusting the forming parameters, namely air cooling (AC), water cooling (WC), and the post-treatment, hot isostatic pressing (HIP), and heat treatment (T6) samples. The impact fracture behavior of samples with Charpy V-notched was studied by an instrumented drop hammer impact testing machine which can provide a load-displacement curve. The important load parameters and the absorbed energy at different stages can be determined by the load-displacement curve. The results show that the impact absorbed energy of the AC/WC/HIP/T6 sample was 1.33 ± 0.20, 1.96 ± 0.26, 1.91 ± 0.18, and 2.54 ± 0.21 J, respectively. The impact fracture mechanism was discussed as the corresponding fractographic observations. Brittle fractures with inhomogeneous dimples were observed in all the samples. The key determinant of the impact toughness was the block-shaped brittle θ phase that precipitated along the grain boundaries and pore defects. The equiaxed/columnar heterogeneous microstructure affects not only the coordinated deformation ability of grains but also the distribution of brittle θ phases. Therefore, compared with the AC sample, the impact toughness of the WC sample with a low-volume fraction θ phase, the HIP sample with low porosity, and the T6 sample with a large amount of ductile θ″/θ' phases was significantly improved. This study provides valuable insights for improving the dynamic impact resistance of Arc-DED fabricated Al-Cu alloy.

Impact fracture mechanism and heat deflection temperature of PLA/PEICT blends reinforced by glass fiber.

To enhance the crack propagation and initiation properties and heat deflection temperature of poly(lactic acid) (PLA), PLA/poly(1,4-cyclohexanedimethylene isosorbide terephthalate) (PEICT) blend systems were prepared and glass fibers (GF) were incorporated as reinforcements. Due to high shear force during extrusion and injection molding the length of GF was reduced and was oriented towards the flow direction. Although the reinforcing effect of the GF deviated from the theoretical values calculated by the Halpin-Tsai equation, both tensile and flexural properties were greatly enhanced with increasing GF content. Dynamic mechanical and thermal testing showed improved storage modulus throughout the entire temperature range showing outstanding reinforcing ability. By incorporating GF into the PLA/PEICT blend, the crack propagation and initiation properties were enhanced compared to pristine PLA. Such an increase in crack propagation properties was the result of enhanced modulus with the added GF. Moreover, because of the increased modulus, the heat deflection temperatures of the GF reinforced blends were drastically increased showing a value of 91.4 °C at 20 wt% GF loading. The high performance reached by the biomass-based composites developed in this research shows great possibility of replacing these conventional petroleum-based polymer systems.

Analiza udarne žilavosti i kritičnog faktora intenziteta napona KIc kod feritno-austenitnih zavarenih spojeva različitim unosom toplote

Introduction/purpose: Constructions always have several critical points that can be sources of possible defects. All these critical places must be taken into account in safety assessment where the most unfavorable exploitation factors are considered and the local safety of a joint is assessed. Today, joints of various compositions are becoming more frequent in metal constructions. Due to the requirements of economy and ecology, welded joints of microalloyed ferritic steels with high-alloyed austenitic steels are increasingly encountered during the construction of power plants, chemical facilities, etc. Tests of such welded joints have been performed on tanks for oil derivatives, where parts of the tank shell are made of microalloyed ferritic steel and the roof structure is made of high-alloyed austenitic steel. Methods: In the paper, an experimental analysis of crack propagation in an austenitic-ferritic welded joint was performed. The welding was performed by the MIG welding process with two different heat inputs, and the same filler material MIG 18/8/6 was used. Two types of welded plates were tested. the characteristics of the base, filler and auxiliary materials and welding 16 technologies are given. Notched test specimens with an initiated crack-type fracture were made in order to determine the impact properties and fracture mechanics parameters. The results: The research carried out within this study aimed to compare the obtained results of the impact toughness and fracture toughness at flat deformation in a ferrite-austenitic welded joint. An evaluation of the results obtained during the testing of the experimental plates welded with different amounts of heat input is also given. Conclusion: These test results established the dependence of the geometry of a propagating crack and the stress conditions for further crack propagation. It is possible to determine the values of the parameters that describe the behavior of the material, both in linear-elastic and in elastoplastic fracture mechanics.

Impact energy absorption and fracture mechanism of FFF made fiberglass reinforced polymer composites

PurposeThe fiber reinforced polymer composites are becoming more critical because of their exceptional mechanical properties and lightweight structures. Fused filament fabrication (FFF) is a three-dimensional (3D) printing technique that can manufacture composite structures. However, the effect of impact performance on the structural integrity of FFF made composites compared to the pre-preg composites is a primary concern for the practical usage of 3D printed parts. Therefore, this paper aims to investigate the effect of different processing parameters on the impact performance of 3D printed composites.Design/methodology/approachThis paper investigates the impact of build orientation, fiber stacking sequence and fiber angle on the impact properties. Two build orientations, three fiber stacking sequences and two different fiber angles have been selected for this study. Charpy impact testing is carried out to investigate the impact energy absorption of the parts. Onyx as a matrix material and two different types of fibers, that is, fiberglass and high strength high temperature (HSHT) fiberglass as reinforcements, are used for the fabrication.FindingsResults indicate that build orientation and fiber angle largely affect the impact performance of composite parts. The composite part built with XYZ orientation, 0º/90º fiber angle and B type fiber stacking sequence resulted into maximum impact energy. However, comparing both types of fiber reinforcement, HSHT fiberglass resulted in higher impact energy than regular fiberglass.Originality/valueThis study evaluates the damage modes during the impact testing of the 3D printed composite parts. The impact energy absorbed by the composite samples during the impact testing is measured to compare the effect of different processing conditions. The investigation of different types of fiberglass reinforced with Onyx material is very limited for the FFF-based process. The results also provide a database to select the different parameters to obtain the required impact properties.

Effect of microstructure homogeneity on the impact fracture mechanism of X100 pipeline steel laser–MAG hybrid welds with an alternating magnetic field

Laser–metal active gas (MAG) hybrid welding has broad application prospects in pipeline steel welding because of the advantages of high penetration and efficiency. Because very little of the wire and shielding gas will reach the bottom of the molten pool, inhomogeneous microstructures will appear in the thickness direction of laser-MAG hybrid welds. In this study, we introduced an alternating magnetic field (AMF) into laser-MAG hybrid welding to study the effect of microstructure homogeneity on the impact fracture mechanism of X100 pipeline steel laser-MAG hybrid welds. The results illustrated that the arc and laser zones of the welds without an alternating magnetic field (WAMF) were composed mainly of acicular ferrite (AF) and lath martensite (LM), respectively. The distribution of inclusions in the thickness direction of the weld became homogeneous, and a homogeneous microstructure composed of AF and LM was obtained in the AMF weld. Among the WAMF and AMF welds, the laser zone of the WAMF weld had the lowest impact toughness due to the low density of the effective grain boundaries and high kernel average misorientation value. The difference in the impact toughness between the laser and arc zones of the WAMF weld led to a difference in the fracture mode. In addition, the impact fracture mechanism of the AF and LM mixed microstructures was investigated, which showed that AF provided a basis for crack deflection and void formation because of its highly effective grain boundary density. The large-angle deflection of the main crack, secondary cracks in the prior propagation direction, and the combined action of plastic deformation and voids improved the impact energy. The results of this study provide guidance for the study of fracture processes in heterogeneous microstructures.

Effect of root welding heat input on microstructure evolution and fracture mechanism in intercritically reheat-coarse grained heat-affected zone of X80 pipeline steel

The impact toughness of X80 pipeline steel welded joints widely used in laying directly affects the service life of pipelines. The intercritically reheat-coarse grained heat-affected zone (ICCGHAZ) is an embrittlement zone in dual pass welded joints due to the existence of M-A constituents. Adjusting the heat input provides the possibility to optimize the microstructure distribution and improve the impact toughness. In this paper, microstructure, especially the M-A constituents, and fracture mechanism with different root welding heat inputs (4 kJ/cm, 6 kJ/cm, 12 kJ/cm) of ICCGHAZ in X80 pipeline steel welding joint were investigated. The results illustrated that the amount of reverted austenite decreased with increasing root welding heat input, which led to the variety of M-A constituent distribution from dense to sparse and type from island to coarse slender. With increasing root welding heat input, the impact energy of ICCGHAZ decreased (32 J→28 J→26 J) owing to the decrease of HAGBs ratio and the variety of M-A constituent types. The toughness of ICCGHAZ could be higher than the base metal at 4 kJ/cm. The impact fracture mechanism schematic diagram at 4 and 12 kJ/cm were summarized. During the impact process, cracks nucleated at the secondary thermal cycle product. Crack deflected when encountered the island-type M-A constituent. While it propagated straightly when encountered the course slender type M-A constituents. The less deflection propagation path could consume less energy and consequently decrease toughness.

A FDEM Parametric Investigation on the Impact Fracture of Monolithic Glass

Due to the brittleness, monolithic glass may fracture under impact, resulting in catastrophic sequences. The combined finite-discrete element method, i.e., FDEM, is employed to investigate both the oblique and the perpendicular impact failures of monolithic glass parametrically, particularly the soda-lime glass. Using FDEM, glass is discretised into discrete elements where a finite element formulation is incorporated, leading to accurate evaluation of the contact forces and structural deformation. Following the basic theories of the FDEM, a cohesive Mode I fracture model of glass is briefly introduced. Numerical examples are given for the verification of the employed fracture model and the applicability of the FDEM, and comparisons have been made against the computational and experimental results in the literature. The investigated parameters include the impact velocity, the impact angle, the material properties of glass, etc. The obtained results not only revealed the impact fracture mechanism of soda-lime glass but also provided guidance for its design and manufacturing.

Fracture mechanism and scratch behaviour of MWNTs reinforced 70/30 (wt/wt) PC/ABS blends and their nanocomposites

In this work, multiwalled carbon nanotubes (MWNTs) are dispersed in 70/30 (wt/wt) polycarbonate (PC)/acrylonitrile butadiene styrene (ABS) (PC70ABS30) blends and their nanocomposites by the melt-processing method. The morphology observations suggest the development of matrix-droplet morphology. There exists an interaction between MWNTs and the PC phase, which is observed from Raman spectroscopic investigation. Dynamic mechanical analysis (DMA) studies show the increase in storage modulus values depicting the stiffening effect of MWNTs, tanδ value increase depicting the energy dissipation. The flexural and impact properties increase significantly. The mechanism of flexural fracture is craze formation in the skin layer with a shear band and facets formation in the bulk region as observed from the SEM investigation of a flexural fractured surface of MWNTs reinforced PC70ABS30 blends and their nanocomposites. In addition, the deformation at the edge, river-like pattern, striation associated shear bands, craze, cavitation, and facets formation are the impact fracture mechanism as observed from SEM investigation of impact fractured surface of MWNTs reinforced PC70ABS30 blends and its nanocomposites. Scratch studies reveal the improved dispersion of MNNTs at 0.5–1 wt% in PC70ABS30 blends and their nanocomposites with a slightly higher scratch coefficient of friction and scratching force.