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This research employs the Taguchi method and analysis of variance (ANOVA) to investigate, analyze, and optimize the impact strength of tough polylactic acid (PLA) material produced through fused deposition modeling (FDM). This study explores the effect of key printing parameters—specifically, infill density, raster angle, layer height, and print speed—on Charpy impact strength. Utilizing a Taguchi L16 orthogonal array experimental design, the parameters are varied within defined ranges. The results, analyzed through signal-to-noise (S/N) ratios and ANOVA, reveal that infill density has the most substantial impact on Charpy impact strength, followed by print speed, layer height, and raster angle. ANOVA identifies infill density and print speed as the most influential factors, contributing 38.93% and 36.51%, respectively. A regression model was formulated and this model predicted the impact strength with high accuracy (R2 = 98.16%). The optimized parameter set obtained through the Taguchi method, namely, a 100% infill density, 45/−45° raster angle, 0.25 mm layer height, and 75 mm/s print speed, enhances the impact strength by 1.39% compared to the experimental design, resulting in an impact strength of 38.54 kJ/m2. Validation experiments confirmed the effectiveness of the optimized parameters.

The effect of dispersing multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in the matrix on the low-velocity impact resistance and post-impact residual tensile strength of the carbon fiber reinforced epoxy composite laminates has been experimentally analyzed in this study. The composite specimens with the matrix reinforced by different nanoparticle types and various nanoparticle concentrations (0.1, 0.3, and 0.5 wt.%) were prepared and impacted. The post-impact tensile quasi-static and fatigue tests were performed on the specimens with different configurations to study the influence of aforementioned factors on the impact resistance and damage tolerance. Experimental results show that adding nanoparticles in the matrix increases the maximum impact force, reduces the damage area, and alleviates the dent depth of the laminates remarkedly. Moreover, the improvement in these impact resistances increases with the applied nanoparticle concentrations. The nano-modified composite laminates present higher post-impact static strength and longer fatigue life than the specimens with a neat epoxy matrix. Furthermore, both the post-impact static tensile strength and fatigue life increase with the applied nanoparticle concentrations. The damage areas measured using infrared thermography were found to increase linearly with the applied fatigue cycles for all the studied specimens with various configurations. The damage area growth rates of nano-modified composite laminates decrease significantly as the applied nanoparticle concentrations increase. The MWCNTs present better performance than GNPs in improving post-impact static strength and extending the residual fatigue life, however the effect of applied nanoparticle type on the fatigue damage growth rate is slight.

The results of studying the effect of particles of few-layer graphene (FLG) synthesized by self-propagating high-temperature synthesis (SHS) on the complex of strength and thermo physical properties of polymer composite products obtained by digital light processing (DLP) 3D printing are presented. It was discovered to achieve an increase in thermophysical and strength parameters of polymers modified by FLG compared with samples made on the unmodified base resin. This result was achieved due to low defectiveness, namely the absence of Stone–Wales defects in the structure of FLG due to the homogeneous distribution of FLG over the volume of the polymer in the form of highly dispersed aggregates. It was possible to increase hardness by 120%, bending strength by 102%, Charpy impact strength by 205%, and thermal conductivity at 25 °C by 572% at concentrations of few-layer graphene of no more than 2 wt. %.

A series of hybrid fiber-reinforced composites were prepared with polyimide fiber and carbon fiber as the reinforcement and epoxy resin as the matrix. The influence of stacking sequence on the Charpy impact and flexural properties of the composites as well as the failure modes were studied. The results showed that hybrid fiber-reinforced composites yielded nearly 50% increment in Charpy impact strength compared with the ones reinforced by carbon fiber. The flexural performance was significantly improved compared with those reinforced solely by polyimide fibers and was greatly affected by the stacking sequence. The specimens with compressive sides distributed with carbon fiber possessed higher flexural strength, while those holding a sandwich-like structure with carbon fiber filling between the outer layers displayed a higher flexural modulus.

Currently, the automotive industry is looking for their new products to have a density as low as possible so that CO 2 emissions decrease. Metallic foams have attracted a great deal of interest in this industry because of their multiple advantages. They can be produced at a relatively low cost and have advantageous properties, especially due to their ability to absorb energy. In the framework of this study, 42 specimens were tested to determine the impact energy and Charpy impact strength according to the cutting orientation. Before being notched according to the ISO 148 standard, their specific mass was determined. For the tests, an Instron CEAST 9050 Charpy test machine was used. The impact strength was determined according to the cutting orientation, and the results obtained by the mass density groups were compared. It could be observed that the cutting orientation of the specimens does not have a clear influence on the impact strength; this is due to the irregular shape of the closed cell, however, the grouping of the specimens on specific density samples has influenced the impact strength.

In the present study, we prepared crosslinked particles of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) to investigate their performance as impact modifiers. The mechanical properties of crystalline PHBH comprising 5.6 mol% 3-hydroxyhexanoate (3HHx) were modified by the addition of amorphous particles of PHBH with 28 mol% 3HHx (PHBH28). The tensile impact strength of the mixture was improved by the addition of PHBH28 particles, particularly when they were crosslinked. The size of the dispersed uncrosslinked PHBH28 particles was sensitive to the processing method. However, the crosslinked PHBH28 particles retained their form under any processing conditions, and a smaller particle size was achieved, leading to shear yielding. The samples containing crosslinked PHBH28 particles exhibited intense stress-whitening after impact testing. The resulting voids were ascribed to cavitation in the particles, which must have been responsible for the improved mechanical properties of the samples. Moreover, the crosslinked particles did not affect the excellent biodegradability of PHBH in seawater.

This study investigates the effects of graphene reinforcement on the hardness and impact strength of glass epoxy composites. Four different materials were examined: pure epoxy (EP), glass epoxy (GE), glass epoxy with 1 wt.% graphene (GE1), and glass epoxy with 2 wt.% graphene (GE2). The results show that the incorporation of graphene significantly enhances the hardness of the composites. Pure epoxy (EP) exhibited a Shore D hardness of 60 and an impact strength of 0.09 J/m2. The glass epoxy (GE) showed a reduction in hardness to 56 but an increased impact strength of 0.15 J/m2 due to the inclusion of 33 wt.% glass fiber. Further addition of graphene in GE1 and GE2 led to notable improvements in hardness, reaching 68 and 74 Shore D, respectively. However, the impact strength displayed a decrease with the inclusion of graphene, with GE1 and GE2 showing values of 0.13 and 0.11 J/m2, respectively. When transitioning from pure epoxy (EP) to glass epoxy (GE), there is a 6.67% decrease in hardness, while the impact strength increases by 66.67%. Introducing 1 wt.% of graphene to the glass epoxy (GE1) results in a 21.43% increase in hardness but a 13.33% decrease in impact strength. Further adding 2 wt.% of graphene (GE2) leads to an additional 8.82% increase in hardness, though the impact strength decreases by 15.38%. X‐ray diffraction (XRD) analysis has revealed nano graphene presence and distribution, while fractography has revealed its effectiveness in enhancing interfacial adhesion and toughening mechanisms. Furthermore, XRD identifies potential changes in crystallinity or phase composition induced by nano graphene incorporation, further elucidating the composite's structure and properties. The study highlights the novel and significant trade‐offs encountered in optimizing the mechanical properties of epoxy‐based composites by incorporating graphene and glass fiber. Influence of nano graphene filler on hardness, impact strength and density of glass epoxy composites

This paper presents an experimental research on the mechanical properties of the hybrid composite thin-plates of the short basalt fibers (CBFs)/carbon textile-reinforced geomortar. The effect of fiber contents and lengths of CBFs on the flexural behavior of carbon textile-reinforced geopolymer specimens (TRGs) was investigated by the four-point flexural strength and Charpy impact test. The experimental results of hybrid TRGs, on the one hand, were compared with reference TRGs, without CBF addition; on the other hand, they were compared with the results of our previous publication. According to the mixing manner applied, fresh geomortar indicated a marked reduction in workability, increasing the CBF loading. Furthermore, using CBFs with lengths of 12 mm and 24 mm makes it easy to form the fiber clusters in geomortar during mixing. According to all the CBF loadings used, it was found that TRGs showed a significant improvement in both static and dynamic flexural strength. However, the failure mode of these TRGs is similar to that of the reference TRGs, described by the process of fiber debonding or simultaneously fiber debonding and collapse. In comparison with our prior work results, neither the CBF dose levels nor the fiber lengths used in this work have yielded a positive effect on the failure manner of TRGs. According to the results of the Charpy impact test, this reveals that the anchoring capacity of textile layers in geomortar plays an important role in specimens’ strength.

Based on differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, polarizing microscope (POM), and scanning electron microscopy (SEM) analysis, strategies to close the gap on applying conventional processing optimizations for the field of 3D printing and to specifically increase the mechanical performance of extrusion-based additive manufacturing of poly(lactic acid) (PLA) filaments by annealing and/or blending with poly(3-hydroxybutyrate) (PHB) were reported. For filament printing at 210 °C, the PLA crystallinity increased significantly upon annealing. Specifically, for 2 h of annealing at 100 °C, the fracture surface became sufficiently coarse such that the PLA notched impact strength increased significantly (15 kJ m−2). The Vicat softening temperature (VST) increased to 160 °C, starting from an annealing time of 0.5 h. Similar increases in VST were obtained by blending with PHB (20 wt.%) at a lower printing temperature of 190 °C due to crystallization control. For the blend, the strain at break increased due to the presence of a second phase, with annealing only relevant for enhancing the modulus.

Depending on the specific alloy composition and iron content, iron can have various effects on aluminum alloys. This work examines the influence of varying Fe content on the Charpy impact, tensile, and hardness properties of cast AlSi7Mg0.3 alloy (356). The samples contained 0.11, 0.25, 0.42, and 0.65 wt% Fe levels. The instrumented Charpy V-notch impact tests, conducted according to the ISO EN 148-3 standard, provided data on maximum impact force, crack initiation, crack propagation, and total Charpy impact resistances. Tensile tests, performed according to EN ISO 6892-1 standard, evaluated the yield strength (YS), ultimate tensile strength (UTS), and elongation (%ε) values. Hardness and density measurements were also taken. Additionally, the fracture surfaces of Charpy V-notch and tensile test samples underwent optical macroscopic and scanning electron microscopic analysis to understand the effects of Fe content. The study revealed that as the Fe content in AlSi7Mg0.3 alloy increases, the tensile properties and Charpy impact resistances decrease.