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Nowadays, the components of carbon fiber-reinforced polymer composites (an important material) are directly produced with 3D printing technology, especially Fused Filament Fabrication (FFF). However, such components suffer from poor toughness. The main aim of this research is to overcome this drawback by introducing an idea of laying down a high toughness material on the 3D-printed carbon fiber-reinforced polymer composite sheet, thereby making a hybrid composite of laminar structure. To ascertain this idea, in the present study, a carbon-reinforced Polylactic Acid (C-PLA) composite sheet was initially 3D printed through FFF technology, which was then laid upon with the Acrylonitrile Butadiene Styrene (ABS), named as C-PLA/ABS hybrid laminar composite, in an attempt to increase its impact toughness. The hybrid composite was fabricated by varying different 3D printing parameters and was then subjected to impact testing. The results revealed that toughness increased by employing higher layer thickness and clad ratio, while it decreased by increasing the fill density, but remained unaffected due to any change in the raster angle. The highest impact toughness (23,465.6 kJ/m2) was achieved when fabrication was performed employing layer thickness of 0.5 mm, clad ratio of 1, fill density of 40%. As a result of laying up ABS sheet on C-PLA sheet, the toughness of resulting structure increased greatly (280 to 365%) as compared to the equivalent C-PLA structure, as expected. Two different types of distinct failures were observed during impact testing. In type A, both laminates fractured simultaneously without any delamination as a hammer hit the sample. In type B, the failure initiated with fracturing of C-PLA sheet followed by interfacial delamination at the boundary walls. The SEM analysis of fractured surfaces revealed two types of pores in the C-PLA lamina, while only one type in the ABS lamina. Further, there was no interlayer cracking in the C-PLA lamina contrary to the ABS lamina, thereby indicating greater interlayer adhesion in the C-PLA lamina.

This work explores the development of biodegradable laminar composite foams for cushioning applications. The focus lies on overcoming the inherent brittleness of starch foams by incorporating various paper types as reinforcement. Tapioca starch and glutinous starch were blended in varying ratios (100:0–0:100) to optimize the base material’s properties. The morphology, density, flexural strength, and impact strength of these starch blends were evaluated. The results revealed a trade-off between impact strength and density, with increasing glutinous starch content favoring impact resistance but also leading to higher density. The optimal ratio of tapioca to glutinous starch for achieving maximum flexural strength and modulus was determined to be 60:40. The flexural strength of the composite material at this ratio reached a peak value of 5.3 ± 0.6 MPa, significantly surpassing the flexural strength of pure tapioca foam, which was measured to be 3.5 ± 0.4 MPa. Building on this foundation, novel laminar composite foams were fabricated using the 60:40 starch blend reinforced with mulberry paper, kraft paper, and newsprint paper. To enhance the interfacial adhesion between the starch matrix and paper reinforcement, a silane coupling agent was employed at a 10 wt% loading on the paper. The incorporation of paper reinforcement into starch foams was found to enhance their mechanical properties. Specifically, flexural strength values increased from 5.3 ± 0.6 MPa for the unreinforced starch foam to 6.8 ± 0.6 MPa, 8.1 ± 0.9 MPa, and 7.4 ± 0.1 MPa when reinforced with mulberry paper, kraft paper, and newsprint paper, respectively. Notably, kraft paper reinforcement led to the most enhancements in flexural strength, flexural modulus, and impact strength. This research paves the way for developing sustainable cushioning materials with competitive mechanical properties using bio-based resources like starch and paper.

Twisted laminar superconducting composite structures based on multi-wall carbon nanotube (MWCNT) yarns were crafted by integrating magnesium and boron homogeneous mixture into the carbon nanotube (CNT) aerogel sheets. After the ignition of the Mg–B–MWCNT system, under the controlled argon environment, the high exothermic reaction between magnesium (Mg) and boron (B) with stoichiometric ratio produced the MgB 2 @MWCNT superconducting composite yarns. The process was conducted under the controlled argon environment and uniform heating rate in the differential scanning calorimetry and thermogravimetric analyzer. The XRD analysis confirmed that the produced composite yarns contain nano and microscale inclusions of superconducting phase of MgB 2 . The mechanical properties of the composite twisted and coiled yarns at room temperature were characterized. The tensile strength up to 200 MPa and Young’s modulus of 1.27 GPa proved that MgB 2 @MWCNT composite is much stiffer than single component MgB 2 wires. The superconductive critical temperature of T c ~38 K was determined by measuring temperature-dependent magnetization curves. The critical current density, J c of superconducting component of composite yarns was obtained at different temperatures below T c by using magnetic hysteresis measurement. The highest value of J c  = 3.39 × 10 7  A cm −2 was recorded at 5 K.

A homogeneous and compact super-aligned carbon nanotube (SACNT)-reinforced nickel-matrix composite was successfully prepared by electrodeposition. The mechanical properties of the laminar SACNT/Ni composites were substantially improved compared with those of pure nickel. With increasing content of SACNTs, the tensile strength of the composite increased and the elongation decreased because of the high-strength SACNTs bearing part of an applied load and the fine-grained strengthening mechanism. The nanohardness of the SACNT/Ni composites was improved from 3.92 GPa (pure nickel) to 4.62 GPa (Ni−4vol%SACNTs). The uniform distribution of SACNTs in the composites and strong interfacial bonding between the SACNTs and the nickel matrix resulted in an improvement of the mechanical properties of the SACNT/Ni composites. The introduced SACNTs refined the nickel grains, increased the amount of crystal twins, and changed the preferred orientation of grain growth.

The well known trade-off between hardness and toughness (resistance to fracture) makes simultaneous improvement of both properties challenging, especially in diamond. The hardness of diamond can be increased through nanostructuring strategies 1 , 2 , among which the formation of high-density nanoscale twins — crystalline regions related by symmetry — also toughens diamond 2 . In materials other than diamond, there are several other promising approaches to enhancing toughness in addition to nanotwinning 3 , such as bio-inspired laminated composite toughening 4 – 7 , transformation toughening 8 and dual-phase toughening 9 , but there has been little research into such approaches in diamond. Here we report the structural characterization of a diamond composite hierarchically assembled with coherently interfaced diamond polytypes (different stacking sequences), interwoven nanotwins and interlocked nanograins. The architecture of the composite enhances toughness more than nanotwinning alone, without sacrificing hardness. Single-edge notched beam tests yield a toughness up to five times that of synthetic diamond 10 , even greater than that of magnesium alloys. When fracture occurs, a crack propagates through diamond nanotwins of the 3C (cubic) polytype along {111} planes, via a zigzag path. As the crack encounters regions of non-3C polytypes, its propagation is diffused into sinuous fractures, with local transformation into 3C diamond near the fracture surfaces. Both processes dissipate strain energy, thereby enhancing toughness. This work could prove useful in making superhard materials and engineering ceramics. By using structural architecture with synergetic effects of hardening and toughening, the trade-off between hardness and toughness may eventually be surmounted. A diamond composite with a hierarchical microstructure possesses a combination of hardness and toughness surpassing that of all known materials.

Fabric-based laminated composites are used considerably for multifaceted applications in the automotive, transportation, defense, and structural construction sectors. The fabrics used for composite materials production possess some outstanding features including being lighter weight, higher strength, and lower cost, which helps explain the rising interest in these fabrics among researchers. However, the fabrics used for laminations are of different types such as knit, woven, and nonwoven. Compared to knitted and nonwoven fabrics, woven fabrics are widely used reinforcement materials. Composites made from fabric depend on different properties such as fiber types, origin, compositions, and polymeric matrixes. Finite element analysis is also further facilitating the efficient prediction of final composite properties. As the fabric materials are widely available throughout the world, the production of laminated composites from different fabric is also feasible and cost-effective. This review discusses the fabrication, thermo-mechanical, and morphological performances of different woven, knit, and nonwoven fabric-based composites.

Recent high-profile fires involving combustible façades have exposed significant gaps in both the understanding and regulation of external wall systems. Modern façade designs frequently employ polymers as insulation and/or laminated composite materials that, while improving energy efficiency, can inadvertently create pathways for vertical fire spread. Thus, there is a need to establish fundamental principles for evaluating the fire spread performance of these systems. Drawing on notable incidents, it is shown how uncontrolled flame spread can defeat compartmentation strategies, compromise occupant egress, and overwhelm firefighting efforts. Extending on previous studies, a performance-based approach to fire spread is proposed, examining four levels of relevance: material properties, product characteristics, assembly configuration, and overall building context. Key factors include combustibility, ventilation effects, and real-world variables (e.g., building characteristics). Case studies of testing methods illustrate both utility and limitations in capturing metrics relevant to façade design. Ultimately, it is advocated that there is an urgent need for rigorous, tailored assessment protocols supported by professional competence, thereby ensuring that complex external wall systems can be designed and managed to balance fire safety with sustainability and safety objectives.

This paper presents the free vibration and buckling analyses of functionally graded carbon nanotube-reinforced (FG-CNTR) laminated non-rectangular plates, i.e., quadrilateral and skew plates, using a four-nodded straight-sided transformation method. At first, the related equations of motion and buckling of quadrilateral plate have been given, and then, these equations are transformed from the irregular physical domain into a square computational domain using the geometric transformation formulation via discrete singular convolution (DSC). The discretization of these equations is obtained via two-different regularized kernel, i.e., regularized Shannon’s delta (RSD) and Lagrange-delta sequence (LDS) kernels in conjunctions with the discrete singular convolution numerical integration. Convergence and accuracy of the present DSC transformation are verified via existing literature results for different cases. Detailed numerical solutions are performed, and obtained parametric results are presented to show the effects of carbon nanotube (CNT) volume fraction, CNT distribution pattern, geometry of skew and quadrilateral plate, lamination layup, skew and corner angle, thickness-to-length ratio on the vibration, and buckling analyses of FG-CNTR-laminated composite non-rectangular plates with different boundary conditions. Some detailed results related to critical buckling and frequency of FG-CNTR non-rectangular plates have been reported which can serve as benchmark solutions for future investigations.

To investigate the bending characteristics of composite laminates, parametric analysis was carried out based on finite element simulation. By analyzing the variation of the bending deflection with the aspect ratio, width thickness ratio, laying angle, and elastic modulus of the structure, the variation rule of the bending characteristics is obtained. The conclusion is as follows: (1) the larger the aspect ratio is, the larger the bending deflection is, but after reaching a certain ratio, the bending deflection begins to appear smaller. (2) the bending deflection changes more and more as the width-thickness ratio becomes larger. (3) the bending deflection of fixed at both ends is much larger than that of fixed at all four ends under the remaining conditions. (4) the larger the elastic modulus ratio is, the smaller the bending deflection is, under the remaining conditions remain unchanged.

The prosthetic socket, which transfers load from the residual limb to the prosthesis, is an integral part of the prosthesis. 3D printing has emerged as a potentially viable alternative to traditional fabrication for producing sockets that effectively transfer loads. We conducted a systematic review to better understand the current state of this newer fabrication method, with a focus on the structural integrity of 3D printed sockets and factors that can affect the strength of 3D printed sockets when tested using ISO 10328 standards. Literature searches were carried out in five databases (PubMed, Scopus, CINAHL, Web of Science and Google Scholar). Two reviewers independently performed the literature selection, quality assessment, and data extraction. A total of 1023 unique studies were screened in accordance with inclusion and exclusion criteria. Of 1023 studies, 12 studies met all inclusion criteria, with failure data for 15 3D-printed sockets and 26 standard laminated sockets. Within 3D printed sockets, the addition of composite materials such as carbon fiber particles and distal reinforcement using a compositing infill technique appears to improve socket strength. In light of the considerable amount of heterogeneity between studies in terms of materials and alignment used, the absolute values for failure could not be established for 3DS nor directly compared between 3DS and LCS. However, there is some evidence that the probability of a failure at a given load may be comparable between 3DS and LCS up to the P8 level. For all sockets, whether a laminated composite socket or a 3D printed socket, failure mainly occurred at the distal end of the socket or the pyramid attachment, which is consistent with the ISO testing protocol. Improving the strength of the 3D printed sockets through design modifications at the distal end and implementing emerging printing technologies could help to promote 3D printed sockets as a viable option, particularly when cost or access to care is limited.