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We introduce the fused sequential addition and migration (fSAM) algorithm for generating microstructures of fiber composites with long, flexible, nonoverlapping fibers and industrial volume fractions. The proposed algorithm is based on modeling the fibers as polygonal chains and enforcing, on the one hand, the nonoverlapping constraints by an optimization framework. The connectivity constraints, on the other hand, are treated via constrained mechanical systems of d'Alembert type. In case of straight, that is, nonflexible, fibers, the proposed algorithm reduces to the SAM (Comput. Mech., 59, 247–263, 2017) algorithm, a well‐established method for generating short fiber‐reinforced composites. We provide a detailed discussion of the equations governing the motion of a flexible fiber and discuss the efficient numerical treatment. We elaborate on the integration into an existing SAM code and explain the selection of the numerical parameters. To capture the fiber length distributions of long fiber reinforced composites, we sample the fiber lengths from the Gamma distribution and introduce a strategy to incorporate extremely long fibers. We study the microstructure generation capabilities of the proposed algorithm. The computational examples demonstrate the superiority of the novel microstructure‐generation technology over the state of the art, realizing large fiber aspect ratios (up to 2800) and high fiber volume fractions (up to 32%$$ 32\% $$ for an aspect ratio of 150) for experimentally measured fiber orientation tensors. [ABSTRACT FROM AUTHOR]

Piezoelectric Carbon Nanotube Reinforced Functionally Graded (P-CNT-FG) structures have great application potential in aerospace for vibration control. The precise modeling technique for P-CNT-FG plates and shells is a big challenge, especially for moderate thick and thick P-CNT-FG structures. This paper develops a Finite Element (FE) model for P-CNT-FG plates and shells. The FE model is derived by Reddy's third-order shear deformation theory with consideration of various CNT distribution forms, CNT volume fractions, boundary conditions and arbitrary fiber orientations. Eight-node quadrilateral elements are developed for P-CNT-FG structures with seven mechanical degrees of freedom (DOFs) at each node. The mathematical model is first validated by a simply supported square plate, a cross-ply plate with sinusoidally distributed loading and a CNT plate with PZT layers. Afterwards, vibration and dynamic responses of P-CNT-FG plates have been presented, later the effective of parameters on static and dynamic response of P-CNT-FG smart structures are carried out by the present model. [ABSTRACT FROM AUTHOR]

Polymer waste in the environment is a more and more serious problem for nature. Therefore, the industry is increasingly interested in the use of materials that are biodegradable. Polybutylene adipate terephthalate (PBAT) belongs to the group of biodegradable polymers, but this polymer often does not have the desired properties for many uses. Therefore, this polymer is often mixed with other biodegradable polymers to form blends with suitable properties. An alternative is, to change the polymer's properties with the addition of fibers. The aim of the present work is to use lyocell fibers to improve the mechanical properties of PBAT. Lyocell is an eco‐friendly cellulose fiber that is biodegradable. The lyocell fibers were embedded into a PBAT matrix in the form of a woven fabric, with different orientations of the fabric warp yarns to the long axis of composites. Consequently, composites with a warp yarn orientation of 0°, ±22.5°, ±45°, ±67.5°, and 90° were prepared. The mechanical properties were characterized by quasi‐static tensile testing and also by dynamic mechanical analysis. The elastic modulus as a function of warp yarn orientation was modeled with the modified rule‐of‐mixture theory and with the theory of elasticity. [ABSTRACT FROM AUTHOR]

The present work investigates the effect of process parameters on the microwave absorption performance of 3D printed continuous carbon fiber reinforced polylactic acid composites in the X‐band (8–12 GHz). The selection of process parameters in this work is based on an orthogonal experiment, explicitly focusing on the fiber orientation and printing temperature. The coupled effect between fiber orientation and printing temperature on the average absorptivity is further investigated by using response surface methodology (RSM), and the mechanism of these parameters on the microwave absorption performance is revealed, resulting in the optimal process parameters with a fiber orientation of 58.39° and a printing temperature of 230°C. The predicted average absorptivity is 0.525 and the mechanical properties of specimens corresponding to optimal parameters have been characterized. The experimental results demonstrate that the optimization of process parameters could lead to a significant improvement in the average absorptivity. Moreover, the microstructure observation shows that voids have the opposite effect on microwave absorption performance and mechanical properties. The above studies have specific guiding significance to the further application of 3D printed continuous fiber reinforced thermoplastic composites in structural absorbing materials. [ABSTRACT FROM AUTHOR]

This study aimed to observe human trapezius muscle (TpzM) development during early fetal period and apply diffusion tensor imaging (DTI) analysis to describe the muscle architecture that leads to physiological functions. Human embryonic and early fetal specimens were selected for this study. TpzM was first detected at Carnegie stage 20. The position of the TpzM changed with the formation of the scapula, clavicle, and vertebrae, which are its insertions and origins. DTI revealed the fiber orientation from each vertebral level to dissect each muscle. Fiber orientation in the ventral view gradually changed from the cervical to thoracic vertebrae, except for the middle part at which the insertions changed, which was almost similar in all early fetal specimens. The TpzM volume increased from C1 to C7 in the upper part, reached local maxima at C6 and C7 in the middle, and then decreased. These muscles can be categorized into three parts according to their insertions and presented with the features of each part. The fiber orientation and distribution of the three parts at the vertebral level were almost constant during the early fetal period. The border between the upper and middle parts was mainly located around the C6 and C7 vertebral levels, whereas the middle and lower parts were between the Th1 and Th2 vertebral levels. A three‐dimensional change in the fiber orientation in the upper part of the TpzM according to the vertebral level was noticeable. Our data will help to elucidate the developmental processes of TpzM. [ABSTRACT FROM AUTHOR]

The use of nano-fillers as reinforcement in natural fibers-based hybrid composites has gained prominence in multiple sectors in recent years because of their virtuous mechanical and physical characteristics. The impeccable properties of nano-fillers like their high aspect ratio and larger surface area have made them to be used in areas for instance, sectors like aviation, automotive, and biotechnology fields. This study focuses on examining how various weight percentages of nano-calcium carbonate (NCaCO3) fillers (2%, 5%, 7%) impact the elastic properties of innovative hybrid composites blended with banana and kenaf fibers, combined with epoxy. The elastic characteristics of the suggested composite, including longitudinal elastic modulus (LEM), transverse elastic modulus (TEM), longitudinal Poisson's ratio (LPR), and longitudinal shear modulus (LSM), are analyzed through micromechanical models such as the Mori–Tanaka (M–TA) model, generalized self-consistent (GS-C) model, and modified Halpin–Tsai (M-HT) model. The composite consisting of a solitary banana fiber sheet, a solitary NCaCO3 mix epoxy sheet, and another solitary kenaf fiber sheet is modeled in ANSYS APDL simulation software. The composite's layers are organized in a specific order: starting with banana fiber at 90° orientations, followed by a layer of NCaCO3 and epoxy at 0° orientations, and concluding with kenaf fiber at 90° orientations. The ANSYS software is employed to analyze the total sum deformation and strength of the suggested composite. The outcomes obtained from this research are contrasted and confirmed through comparison with existing literature. The inclusion of 7 wt% of NCaCO3 in the suggested hybrid composite is found to have the highest elasticity and ductility in comparison with 2 wt% and 5 wt% of NCaCO3. The composite containing 7 wt% NCaCO3 demonstrates the greatest load-bearing capability. Additionally, while calculating the elastic characteristics of the proposed composite, both the modified Halpin–Tsai (M-HT) model and the generalized self-consistent model (GS-C) outperform the Mori–Tanaka model (M–TA). Furthermore, the hybrid impact is computed for the suggested composite to analyze the tensile strain rates at which failure occurs for banana and kenaf fibers within the composite hybrid structure. The computed hybrid value of 0.5 indicates that the failure rate of a non-hybridized composite is 50% more than the hybridized composite. This signifies that the hybrid composites have high load-bearing strength, high elasticity, and stiffness. [ABSTRACT FROM AUTHOR]

The verification of fiber orientation and layup in carbon fiber-reinforced polymer (CFRP) composite laminates is essential to guarantee the performance of the material. This work reports the background, methodology, and results of a rotational eddy current testing (ECT) system for determining fiber orientation and ply layup of unidirectional CFRP components. The system presented mechanically rotates a 15 MHz directional transmit-receive ECT probe, which poses several speed and consistency advantages. The paper presents a theoretical discussion of how these scans are produced, a unique preprocessing normalization method, and an optimization process for determining the layup from the captured datasets. Results show a high level of accuracy for identifying the unique directions present in a laminate, and the theory-supported model enables the extraction of layup order information of multilayer parts, even where repeated lamina are present within the laminate. [ABSTRACT FROM AUTHOR]

Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes, becoming sometimes life threatening for the patients. Therefore, aggressive antibiotic therapies are administered, which often require the use of last‐resort drugs, if the infection is caused by multi‐drug‐resistant bacteria. Reducing the risk of bacterial contamination of medical devices in the hospitals has thus become an emerging issue. Promising routes to control these infections are based on materials provided with intrinsic bactericidal properties (i.e., chemical action) and on the design of surface coatings able to limit bacteria adhesion and fouling phenomena (i.e., physical action), thus preventing bacterial biofilm formation. Here, we report the development and validation of coatings made of layer‐by‐layer deposition of electrospun poly(vinylidene fluoride‐co‐trifluoro ethylene) P(VDF‐TrFE) fibers with controlled orientations, which ultimately gave rise to antifouling surfaces. The obtained 10‐layer surface morphology with 90° orientation fibers was able to efficiently prevent the adhesion of bacteria, by establishing a superhydrophobic‐like behavior compatible with the Cassie‐Baxter regimen. Moreover, the results highlighted that surface wettability and bacteria adhesion could be controlled using fibers with diameter comparable to bacteria size (i.e., achievable via electrospinning process), by tuning the intra‐fiber spacing, with relevant implications in the future design of biomedical surface coatings. [ABSTRACT FROM AUTHOR]

Purpose: To fully characterize the orientation dependence of magnetization transfer (MT) and inhomogeneous MT (ihMT) measures in the whole white matter (WM), for both single‐fiber and crossing‐fiber voxels. Methods: A characterization method was developed using the fiber orientation obtained from diffusion MRI (dMRI) with diffusion tensor imaging (DTI) and constrained spherical deconvolution. This allowed for characterization of the orientation dependence of measures in all of WM, regardless of the number of fiber orientation in a voxel. Furthermore, the orientation dependence inside 31 different WM bundles was characterized to evaluate the homogeneity of the effect. Variation of the results within and between‐subject was assessed from a 12‐subject dataset. Results: Previous results for single‐fiber voxels were reproduced and a novel characterization was produced in voxels of crossing fibers, which seems to follow trends consistent with single‐fiber results. Heterogeneity of the orientation dependence across bundles was observed, but homogeneity within similar bundles was also highlighted. Differences in behavior between MT and ihMT measures, as well as the ratio and saturation versions of these, were noted. Conclusion: Orientation dependence characterization was proven possible over the entirety of WM. The vast range of effects and subtleties of the orientation dependence on MT measures showed the need for, but also the challenges of, a correction method. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to develop a model‐based deep learning architecture to accurately reconstruct fiber orientation distributions (FODs) from a reduced number of diffusion‐weighted images (DWIs), facilitating accurate analysis with reduced acquisition times. Methods: Our proposed architecture, Spherical Deconvolution Network (SDNet), performed FOD reconstruction by mapping 30 DWIs to fully sampled FODs, which have been fit to 288 DWIs. SDNet included DWI‐consistency blocks within the network architecture, and a fixel‐classification penalty within the loss function. SDNet was trained on a subset of the Human Connectome Project, and its performance compared with FOD‐Net, and multishell multitissue constrained spherical deconvolution. Results: SDNet achieved the strongest results with respect to angular correlation coefficient and sum of squared errors. When the impact of the fixel‐classification penalty was increased, we observed an improvement in performance metrics reliant on segmenting the FODs into the correct number of fixels. Conclusion: Inclusion of DWI‐consistency blocks improved reconstruction performance, and the fixel‐classification penalty term offered increased control over the angular separation of fixels in the reconstructed FODs. [ABSTRACT FROM AUTHOR]

The use of nano-fillers as reinforcement in natural fibers-based hybrid composites has gained prominence in multiple sectors in recent years because of their virtuous mechanical and physical characteristics. The impeccable properties of nano-fillers like their high aspect ratio and larger surface area have made them to be used in areas for instance, sectors like aviation, automotive, and biotechnology fields. This study focuses on examining how various weight percentages of nano-calcium carbonate (NCaCO3) fillers (2%, 5%, 7%) impact the elastic properties of innovative hybrid composites blended with banana and kenaf fibers, combined with epoxy. The elastic characteristics of the suggested composite, including longitudinal elastic modulus (LEM), transverse elastic modulus (TEM), longitudinal Poisson's ratio (LPR), and longitudinal shear modulus (LSM), are analyzed through micromechanical models such as the Mori–Tanaka (M–TA) model, generalized self-consistent (GS-C) model, and modified Halpin–Tsai (M-HT) model. The composite consisting of a solitary banana fiber sheet, a solitary NCaCO3 mix epoxy sheet, and another solitary kenaf fiber sheet is modeled in ANSYS APDL simulation software. The composite's layers are organized in a specific order: starting with banana fiber at 90° orientations, followed by a layer of NCaCO3 and epoxy at 0° orientations, and concluding with kenaf fiber at 90° orientations. The ANSYS software is employed to analyze the total sum deformation and strength of the suggested composite. The outcomes obtained from this research are contrasted and confirmed through comparison with existing literature. The inclusion of 7 wt% of NCaCO3 in the suggested hybrid composite is found to have the highest elasticity and ductility in comparison with 2 wt% and 5 wt% of NCaCO3. The composite containing 7 wt% NCaCO3 demonstrates the greatest load-bearing capability. Additionally, while calculating the elastic characteristics of the proposed composite, both the modified Halpin–Tsai (M-HT) model and the generalized self-consistent model (GS-C) outperform the Mori–Tanaka model (M–TA). Furthermore, the hybrid impact is computed for the suggested composite to analyze the tensile strain rates at which failure occurs for banana and kenaf fibers within the composite hybrid structure. The computed hybrid value of 0.5 indicates that the failure rate of a non-hybridized composite is 50% more than the hybridized composite. This signifies that the hybrid composites have high load-bearing strength, high elasticity, and stiffness. [ABSTRACT FROM AUTHOR]

Sandwich panels with trapezoidal metal/glass fiber cores are increasingly popular due to their lightweight and energy-absorption properties. This study employs response surface methodology (RSM) and Box-Behnken design to investigate the effects of core angle, fiber orientation, and MCM-48 nanoparticles on the panels' energy absorption and peak force, developing regression models with high R2 values of 0.9027 and 0.9228, respectively. Experimental tests were conducted to validate these models, showing minimal deviation from predicted values. Results indicate that increasing the fiber orientation angle from 30° to 90° enhances energy absorption and peak force by 72.18 and 46.9%, respectively, and adding MCM-48 nanoparticles up to 0.25% weight improves energy absorption by 60.8%. A core angle of 52° balances energy absorption and peak force, while integrating a metal wire mesh within the panels significantly enhances energy absorption and reduces core brittleness. The optimal parameters for maximum energy absorption and minimum peak force include a core angle of 58°, fiber orientation of 73.5°, and no nanoparticles. These findings provide valuable insights into the design and optimization of sandwich panels for various applications. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the ultrastructural anatomy of the developing ACL tibial enthesis. We hypothesized that enthesis architecture would progressively mature and remodel, eventually resembling that of the adult by the early postnatal stage. Five fresh‐frozen human pediatric cadaveric knees aged 1–36 months underwent anatomical dissection to harvest the ACL insertion and underlying tibial chondroepiphysis. The samples were prepared for scanning electron microscopy (SEM) to examine the ultrastructural anatomy of the enthesis and underwent histological staining for circular polarized light (CPL) and light microscopy imaging. SEM analysis of the 1‐ and 8‐month‐old samples revealed a shallow interdigitation between the dense fibrous (ligamentous) tissue and unmineralized chondrogenic tissues, with a minimal transition zone. By 11‐month, a more complex transition zone was present. By age 19‐ and 36‐month‐old, a progressively more complex and defined fibrocartilage zone was observed. CPL analysis revealed distinct collagen fiber continuity, alignment, and organization changes over time. By 19 and 36 months, the samples exhibited complex fiber arrangements and a progression toward uniform fiber orientation. Similarly, histological analysis demonstrated progressive remodeling of the enthesis with increasing age. Our results suggest that the ACL enthesis of the developing knee begins to mimic that of an adult as early as 19 months of age, as a more complex transition between ligamentous and chondro‐epiphyseal tissue can be appreciated. We hypothesize that the observed changes are likely due to mechanical loading of the enthesis with the onset of weightbearing. Future investigations of ACL reconstruction and repair will benefit from improved understanding of the chondro‐epiphyseal/ACL regions. [ABSTRACT FROM AUTHOR]

The extrusion procedure used to manufacture Short Fiber Reinforced Composites (SFRCs) results in significant anisotropy in the components due to the skin‐core structure. While there are existing accurate stiffness prediction methods available, there is still a need in engineering for an efficient and cost‐effective prediction method. This work proposes an efficient, low‐cost and effective stiffness prediction method for skin‐core structure using the orientation averaging method and series–parallel model. Initially, the sample is analyzed using industrial CT and metallographic microscopy to ascertain the fiber characteristics and skin‐core dimensions. Furthermore, it is presumed that the skin and core are distinct materials and their stiffness is determined using the orientation averaging method. Finally, the stiffness of the sample is determined by employing a series–parallel model for analyzing stress–strain transmission, which involved merging the skin and core components. Experimental and finite element results confirm the method's accuracy, boasting a calculation time of 31.36 s and a maximum stiffness error below 10%. This method is expected to be applied to automotive, construction and other engineering fields to meet the demand for fast, cost‐efficient and effective stiffness prediction of SFRCs. Highlights: A stiffness prediction method is proposed, which is no modeling required.Combined with Hashin‐Tsai, orientation average method and series–parallel model.The stiffness of skin‐core structure is predicted by this method within 31.36 s.This method can be extended to more complex fiber orientation examples. [ABSTRACT FROM AUTHOR]

Impact-induced defects in carbon fiber-reinforced polymers (CFRPs)-spanning from nanometer to macroscopic length scales-can be monitored using an aggregate of X-ray-based methods, but this is impractical in typical field conditions. We report on a low-velocity impacted CFRP, which is mapped using small- and wide-angle X-ray scattering and X-ray computed tomography, and employ machine learning for correlating material parameterizations derived from these techniques. The observed 1 μ m to 1 mm-sized defects are parameterized in terms of relative density and fiber orientation indicative of fiber failures (kink bands), and the nanometer sized defects in terms of crystal size and unit cell frustration. The 30 to 300 nm defects are parameterized by a power-law scattering decay, differentiating fractal-like behaviors. We find three spatial domains experimentally and by K-means Clustering: Domains of severe damage (with a visual dent), intact domains (without visual or measurable defects) and a transition domain (defects measurable by X-rays). How the parameters are correlated and how they overlap between the domains are discussed. All parameters are able to point to the detrimental fiber breakage in the severe damage domain, and scattering decay also in the transition domain, for example. How individual parameters determined from one experimental technique can be predicted from that of another is also described. [ABSTRACT FROM AUTHOR]

Hydrogels with high strength, high modulus, and high toughness have great application potential in the field of artificial human load‐bearing tissues, but the preparation of materials with the above high performance is still a huge challenge. In this paper, a structural construction strategy of ordered‐to‐disordered (OTD) transition is proposed to obtain hydrogel fibers with high strength, high modulus, and high toughness. The structural construction strategy of OTD refers to the ordered‐to‐disordered transition of molecular segments in PVA polymer fibers through swelling and subsequent salting‐out treatment, while still maintaining the general order of the entire polymer chain. PVA molecular chain crystallites provide physical crosslinking to stabilize the structure. The results show that the elongation at break of the hydrogel fiber can reach 257%). The strength reaches 190.04 MPa, which is more than 4 times higher than that of human ligaments. The modulus reaches 137.31 MPa, which perfectly matches the human ligaments, and the toughness can reach 100.61 MJ m−3. In addition, it has stable mechanical properties in liquid environment and excellent biocompatibility, which has great application potential in the field of artificial ligaments. This OTD structural construction strategy provides a facile approach to achieving hydrogel fibers with desired mechanical properties. [ABSTRACT FROM AUTHOR]

In the present research work, a comprehensive study on the stress analysis in the two composite pipes bonded by a layer of DP 410 adhesive and a socket buried in the soil has been performed. The pipe material was considered as a four layers of epoxy-fiber glass with different fiber orientations (cross-ply, angle-ply and quasi-isotropic). The soil dimensions and properties as well as the traffic load (H-20) were based on AASHTO. The simulation of the stress analysis was performed using ANSYS software. In the present study, the influences of bed distance, temperature change, internal pressure, traffic load, fiber orientation angle and layups, and gap distance on stress distribution in the buried composite pipe have been investigated. The findings revealed that the annual temperature change in the soil and the pipe enhances the stresses in the joint components to a maximum value of 5.5 MPa at a pipe temperature of −22 °C. Moreover, the outcomes indicated that the adhesive layer is the most sensitive component to any rise in the load prism, as well as other loads, for a buried pipe at a depth of 120 cm. The maximum and minimum state for von Mises stress component were related to, in turn, quasi-isotropic and angle-ply laminations. [ABSTRACT FROM AUTHOR]

Highlights The extensive use of multidirectional composite laminates requires to understand the delamination behavior at interfaces between plies with different fiber orientations. In this study, double cantilever beam testing was performed to investigate the mode I interlaminar fracture of carbon fiber reinforced polymer laminates with different central interfaces (0//0, 0//+45 and +45//−45). X‐ray microtomography revealed the curved crack front shape that was incorporated to calculate fracture toughness. The fracture toughness varies with the crack length in a typical delamination resistance curve, which can be quantified by an empirical equation. Incorporation of variable fracture toughness into a cohesive zone model can better predict the delamination fracture of the laminate, compared to constant toughness. It was found that the delamination mechanism is independent of central interfaces. However, compared to unidirectional laminates, multidirectional laminates are less resistant to crack initiation, but more resistant to propagation with higher toughness and shorter fiber bridging zone. Mode I interlaminar fracture of CFRP laminates with different central interfaces was investigated experimentally and numerically. Curved crack front shape was incorporated to calculate fracture toughness. Incorporation of variable fracture toughness into a cohesive zone model can better predict the delamination fracture of the laminate. Multidirectional laminates are less resistant to crack initiation but more resistant to propagation with higher toughness and shorter fiber bridging zone. [ABSTRACT FROM AUTHOR]

An approach that combines a modified electrospinning method with thermal stretching post‐treatment is designed to fabricate poly(l‐lactide‐co‐ε‐caprolactone) (PLCL) electrospun nanofiber yarns (ENYs). The nanofiber diameter in the PLCL ENYs is found to present an increasing trend with the increasing of polymeric concentration. When the PLCL concentration reaches 13% (w/v), the as‐generated ENYs show bead‐free and uniform nanofibrous structure. Then, a thermally stretching technique is applied to process the primarily‐obtained PLCL ENYs. When the stretching temperature is set as 60 °C, the thermally‐stretched PLCL ENYs present superior fiber orientation and notably enhanced crystallinity, thus resulting in dramatically increased mechanical properties. Finally, the thermally stretched PLCL ENYs are further processed into braided fabrics, and their mechanical properties are found to possess an obviously increased trend with the increasing of ENY numbers, demonstrating the adjustment feasibility of the mechanical properties of ENY‐based textiles by controlling the ENY numbers. Importantly, the in vitro cell studies demonstrate that the ENY‐based braided textiles significantly support the adhesion and proliferation of human dermal fibroblasts (HDFs). In all, the present study provides an easily‐handling strategy to fabricate high performance PLCL ENYs, which shows promising future for the generation of advanced biomedical textiles. [ABSTRACT FROM AUTHOR]

Grinding could be used to enhance accuracy and quality of carbon fiber‐reinforced poly‐ether‐ether‐ketone (CF/PEEK) composites. However, the grinding mode, namely up‐grinding (UG) or down‐grinding (DG), is usually neglected while unbefitting grinding mode choice may cause inferior surface quality. To investigate effects of grinding modes on grinding performance of anisotropic CF/PEEK, grinding experiments in UG and DG were carried out under different fiber orientation angles θ. Experimental results indicated that maximum grinding temperatures and normal grinding forces in UG were lower than DG regardless of the abrasive grit sizes. Material removal mechanisms of CF/PEEK affected by grinding mode were revealed by analyzing morphologies of surface, chip and grinding wheel. When θ = 0°, the dominant mechanisms in DG were extrusion fracture and fiber deformation, while they were interface shear debonding and bending fracture in UG. When θ = 90°, the dominant mechanisms in DG included interface layer separation and bending fracture, while they were shear and extrusion fracture of well‐supported fibers in UG. Thus, UG was more favorable for material removal, obtaining lower surface roughness values, fewer machining defects and less wheel wear than DG. This study will provide technical guidance for high‐quality grinding of carbon fiber‐reinforced thermoplastic composites. Highlights: The effects of grinding modes (DG and UG) on the grinding performance of anisotropic CF/PEEK composites were investigated.Material removal mechanisms of CF/PEEK affected by grinding mode were revealed under different fiber orientation angles.The maximum grinding temperatures and normal grinding forces in UG were lower than DG.UG was more favorable for material removal in grinding, and could produce better ground surface quality than DG. [ABSTRACT FROM AUTHOR]

Highlights An image‐based fiber orientation analysis technique has been employed to study the effect of initial charge coverage and preferential fiber alignment on the flow‐induced fiber orientations in carbon fiber sheet molding compounds (SMCs). The initial charge coverage area exhibited minimal fiber reorientation while significant fiber alignment in the flow direction was observed in the regions of greatest flow. Novel subsurface analysis using the same full‐field orientation analysis technique also showed the presence of a skin‐core structure with greater flow‐induced fiber alignment at the mold surfaces, while the core retained more of the initial fiber orientation distribution. Edge effects were also revealed by this analysis at the mold walls. Tensile testing from two orthogonal directions showed that panels molded from lower charge coverage resulted in better mechanical performance and lower anisotropy. Moreover, by encouraging charge flow in the preform's preferential alignment direction, high tensile stiffness and strength in the preferred direction were achieved (56.7 GPa and 238.9 MPa, respectively) at 30% fiber volume fraction. This provides a practical demonstration of the value in controlling fiber orientation, with respect to charge positioning and mold flow, to maximize and tailor the composite performance of SMCs typically used for automotive applications. Low‐cost scanning technique is extended to assess internal fiber orientations Full‐field orientations are measured before and after molding Investigation of how charge size and shape can affect orientations Combining effects of flow and initial orientation to tailor SMC performance Circular statistics provides a thorough analysis of orientation distributions [ABSTRACT FROM AUTHOR]

In this study, we evaluated the effects of the fiber orientation and the presence of resin-rich layers on electromagnetic induction testing (EIT) of carbon fiber reinforced thermoplastics (CFRTPs). First, a finite-element analysis was performed to evaluate the distribution and path of the eddy and displacement currents induced in interlaminar conductive and interlaminar non-conductive CFRTP specimens. Second, interlaminar electrically conductive and interlaminar non-electrically conductive specimens of unidirectional CFRTP and cross-ply laminated CFRTP were fabricated using a 3D printer, with control of the number of PA-6 layers and fiber orientation. EIT of the specimens revealed that the presence of resin-rich layers and fiber orientation affected the measured EIT output. The results also indicated that the EIT of CFRTP with resin-rich layers requires penetration of displacement currents between the layers. [ABSTRACT FROM AUTHOR]

This research investigates the statistics in terms of mean and coefficient of variance of thermal buckling temperature of shape memory alloy (SMA) fiber-reinforced composite laminated plate using polynomial chaos (PC). The basic mathematical formulation is adopted based on Co finite element method (FEM) in conjunction with secant function-based shear deformation theory. The uncertain input system properties in material and geometrical parameters are modeled as random variables. The effects of SMA fiber and location, pre-strain, loading, modes, temperature distribution, modulus ratio, fiber orientation, length-to-thickness ratio, aspect ratio, and various boundary conditions on the statistics of critical temperature are analyzed. The small amount of random change in input system parameters significantly affects the variance and reliability of SMA fiber-reinforced composite laminated plate thermal buckling temperature under uniform and non-uniform temperature variations. The present PC simulation's results are compared with independent Monte Carlo simulation and those existing in the literature. [ABSTRACT FROM AUTHOR]

This article aims to investigate the fatigue life prediction methodologies of composite laminates and lay the groundwork for establishing fatigue life evaluation technology for composite structures. By extending the Hashin criterion to the fatigue failure criterion, an empirical equation for the fatigue life of unidirectional laminates with various fiber orientation is simply created. In view of the influence of the stiffness reduction coefficient of the failure layer, the failure sequence of each layer in the laminate is determined under time-varying loads. On the basis of the equivalence principle of fatigue damage, the equivalent life of the failure layer to the remaining layers in laminate is determined by considering the effects of load interaction, variable loading, and load cycles on damage. In combination with equivalent life, the fatigue life prediction model for composite laminates is constructed, and the proposed model agrees will with the test data. [ABSTRACT FROM AUTHOR]

A new approach to an automatable fiber impregnation and consolidation process for the manufacturing of fiber-reinforced composite parts is presented in this article. Therefore, a vacuum chamber sealing machine classically used in food packaging is modified for this approach—Vacuum Chamber Infusion (VCI). Dry fiber placement (DFP) preforms, made from 30 k carbon fiber tape, with different layer amounts and fiber orientations, are infused with the VCI and with the state-of-the-art process—Vacuum Assisted Process (VAP)—as the reference. VCI uses a closed system that is evacuated once, while VAP uses a permanently evacuated open system. Since process management greatly influences material properties, the mechanical properties, void content, and fiber volume fraction (FVF) are analyzed. In addition, the study aims to identify how the complexity of a resin infusion process can be reduced, the automation potential can be increased, and the number of consumables can be reduced. Comparable material characteristics and a reduction in consumables, setup complexity, and manufacturing time by a factor of four could be approved for VCI. A void content of less than 2% is measured for both processes and an FVF of 39% for VCI and 45% for VAP is achieved. [ABSTRACT FROM AUTHOR]

Spinning fibers from carbon nanotube (CNT)/superacid dispersions has emerged as a promising strategy for industrial‐scale production of high‐performance CNT fibers (CNTFs). The oxygen content and types of functional groups on CNT surfaces significantly influence dispersion, assembly processes, and fiber properties. In this study, Tuball‐SWCNTs were purified and oxidized at varying levels. The dispersion behavior of CNTs with different oxidation levels in chlorosulfonic acid was systematically observed, and the mechanical properties of fibers spun from these dispersions were compared. By adjusting the dispersion concentration, highly oriented CNTFs were produced with a specific strength of 1.03 N/tex, a tensile strength of 1.59 GPa, and an electrical conductivity of 3.58 MS/m. Further investigations indicated that oxygen‐containing functional groups decrease the coagulation rate, increasing the maximum draw ratio during spinning and improving CNT alignment in the fibers. Molecular dynamics simulations demonstrated that these functional groups (−OH, ‐COOH) enhance load transfer between CNTs through hydrogen bonding. This specific strength is the highest achieved using Tuball‐SWCNTs for superacid‐spun fibers, surpassing previous works due to the oxidation‐controlled coagulation rate, enhanced fiber orientation, and improved load transfer via hydrogen bonding. This study provides insights for designing and optimizing high‐performance CNTFs. [ABSTRACT FROM AUTHOR]

In the interest of developing a comprehensive understanding of the drilling process using the hole saw tool, this article aims to build a three-dimensional (3D) micromechanical model representing the orthogonal cutting of CFRP using one tooth of the hole saw tool. For this purpose, a finite element model is developed using Abaqus Explicit code. The influence of various drilling parameters like rake angle, inclination angle and cutting-edge radius on the drilling quality is explored. Especially, chip formation mechanisms, cutting force and lateral damage are analyzed. Through finite element simulations and computational analyses, it is found that these outputs results are highly influenced by drilling parameters. When the fiber orientation angle is set to 0°, increasing the rake angle results in a change in the chip formation mechanism from buckling to bending. In contrast, with a fiber orientation angle of 90°, bending and shear governs the chip formation process, irrespective of the rake angle. In both cases, whether the fiber orientation angle is 0° or 90°, chips tend to fragment more favorably with increasing the inclination angle. Regarding the cutting-edge radius, when the fiber orientation angle is 0°, an increase in the cutting-edge radius leads to a transition in the chip-forming mechanism from buckling to bending. However, for a fiber orientation angle of 90°, the chip formation remains governed by bending even as the cutting-edge radius changes. Decreasing the rake angle, the inclination angle, and the cutting-edge radius contribute to a reduction of the cutting force. As the inclination angle and the cutting-edge radius increase, the lateral damage increases, while the rake angle has showed a negligible impact on the damage. These results provide a guidance on the appropriate hole saw tool parameters for a good drilling quality namely, a rake angle of 20°, an inclination angle of 5° and a cutting-edge radius of 0.03 mm. [ABSTRACT FROM AUTHOR]

Opossums (marsupials of the Didelphidae family) retain a generalized masticatory apparatus and tribosphenic molars, often used as models to understand the evolution of mastication in early therian mammals. Like all marsupials, their growth goes through a stage when pups complete their development while permanently attached to the mother's teats before weaning and starting feeding on their own. Yet, while the masticatory muscles of adults are known, as is the ontogeny of the cranium and mandible, the ontogenetic changes in the masticatory muscles remain unknown. Here we describe for the first time the changes in the masticatory muscles observed in lactating pups, and weaned juveniles, subadults, and adults in the White‐eared opossum, Didelphis albiventris, through dissection of 25 specimens and quantification of relative muscle masses, lines of actions and mechanical advantages whenever possible. We also assessed the scaling patterns of muscle masses and mechanical advantages through ontogeny. The main changes, as expected, were found between suckling and weaned specimens, although some changes still occurred from juveniles to adults. The adult adductor musculature is similar to the other Didelphis species already known, with a dominant m. temporalis that originates on the lateral wall of the skull, up to the sagittal and nuchal crests, and fills the zygomatic arch when inserting into the lateral and medial surfaces of the coronoid process, respectively through the pars superficialis and pars profunda. The m. masseter is also subdivided in superficial and deep bundles which originate posteriorly in the maxilla and zygomatic arch, and insert into the angular process and masseteric fossa in the mandible. The m. pterygoideus medialis originates from the palatine, the pterygoid bone and the alisphenoid, and it inserts on the angular process medially. Suckling pups showed muscles with more restricted attachments, reduced muscle lines of action, and less diversity in the fiber orientation. The absence of the postorbital constriction also resulted in a distinct morphology of the m. temporalis pars profunda, through two bundles, one anterior and one posterior, which insert more inferiorly into the mandible. These major changes can be related to the onset of mastication and to size‐related changes in growing weaned age classes. In general, all adductor muscles grew with positive allometry, and increased their fixation areas through, in part, the development of specific regions of the cranium and mandible. Their lines of action also increase and diversify along ontogeny. These changes can be related to the functional requirements for fixation during lactation, which shift to adduction and mastication movements after weaning. [ABSTRACT FROM AUTHOR]

Compared with metals, composites have unique advantages, such as lightweight, high specific strength and suitable stiffness, high energy absorption, and ease of design,making them worthy of special consideration. Corrugating the surface of energy absorbers makes it possible to control and optimize the crashworthy properties of the composite structure. In this study, the effect of corrugation geometric parameters on the tube surface of the glass-epoxy, under oblique and axial impact, was numerically investigated using the ABAQUS software by considering cohesive layers. There was an excellent agreement between the simulation results and the validated experimental ones. The effect of amplitude and wavelength of the corrugated wall of the composite tapered tube, the angles of the cone tip and oblique impact, the orientation of the composite fibers, and composite layer on the absorption energy, the peak force, and crushing force efficiency related to the composite tube were examined. The results indicated that the energy absorption capacity of the tapered composite tube reduces by decreasing the angles of the cone tip and increasing oblique impact. Moreover, one can control the crashworthy properties of the composite tube by modifying the amplitude and wavelength of the corrugated surface, and the angles of fiber and layering. [ABSTRACT FROM AUTHOR]

The current paper is devoted to investigate the free and forced vibrational responses of the multi-phase angle-ply laminated nanocomposite beam with focusing on the occurrence of resonance phenomenon. The influence of uniform thermal loading and three-parameter Kerr substrate which can affect the resonance behavior of the structure is surveyed. Utilizing a superior nanofiller with the name of Graphene Oxide (GO) together with the macro-scale Carbon Fibers (CFs) will constitute a novel multi-scale hybrid reinforcement for the polymer matrix. The combination of the Halpin–Tsai micromechanical model and extended rule of the mixture is implemented to estimate the effective properties of this multi-scale hybrid nanocomposite. Refined higher-order beam theory is employed to obtain the displacement fields and then with applying Hamilton's principle, the governing equations are derived and analytically solved via Galerkin's exact solution method. Also, the presented results are validated with reputed works in open literature. Furthermore, some tabulated and graphical results are provided to reveal the effects of various parameters such as fibers' orientation angle, weight and volume fractions of reinforcements, different boundary conditions, beam's slenderness ratio, Kerr substrate parameters, excitation frequency and temperature change on the dynamic behavior of the proposed structure. [ABSTRACT FROM AUTHOR]

Due to the anisotropic characteristic of carbon fiber-reinforced silicon carbide ceramics, the fiber orientation angle significantly affects the grinding force. Therefore, it is important to study the influence rule of different fiber orientations on the grinding force of 2.5D-Cf/SiC composites. To study the comprehensive influence of machine tool parameters and the anisotropy of carbon fiber-reinforced ceramic matrix composites on the grinding force, two-dimensional ultrasonic plane grinding was studied by orthogonal test and single-factor experiment. Based on the multi-exponential fitting analysis method of multiple linear regression equation, the empirical equations of power exponential grinding force prediction model of 2D ultrasonic-assisted grinding and conventional grinding 2.5D-Cf/SiC composites at 0°, 45°, and 90° fiber orientation and considering fiber orientation and ultrasonic amplitude were established, respectively. To verify the empirical formula model in predicting the grinding force of 2.5D-Cf/SiC composites under various fiber orientation angles, the regression equation and regression coefficient of the model were examined. The influence of 2.5D-Cf/SiC grinding parameters on the grinding force was analyzed. The parameters of the grinding force model were optimized based on range analysis and variance analysis, and the optimal process parameter combination was obtained. The results show that the grinding force is negatively correlated with the linear speed and positively correlated with the feed speed and grinding depth within the range of experimental parameters. The maximum reduction of the normal grinding force is 29.78% when the line speed is 10.48 m/s, the feed speed is 100 mm/min, the grinding depth is 50 μm, and along the 45° fiber direction. The optimal grinding parameter combination is a line speed of 23.60 m/s, feed speed of 5 mm/min, and grinding depth of 10 μm along the 0° fiber orientation. [ABSTRACT FROM AUTHOR]

Due to their advantages of high rupture strength and long service life, polymer fibers are often used for soil improvement. However, there is no consensus on how the mixing of discrete polymer fibers affects the stress–strain relationship of clays. In this study, a constitutive relationship of polymer fiber‒reinforced clay was established on the basis of the stress–strain relationship between clay and polymer fibers. The elastic–plastic unified hardening (UH) model was employed, and the fiber contribution was introduced based on the UH model. The constitutive relationship of polymer fiber‒reinforced clay considers the anisotropic distribution of the discrete fiber orientation and the relative sliding between the fibers and clay matrix. The model was verified by referring to the results of consolidated undrained (CU) and consolidated drained tests of typical polymer fiber‒reinforced clays in previous studies. A series of CU tests on rubber fiber‒reinforced clay were conducted to validate the model further. The ratio of the simulated results to the experimental results gradually approached 1 with increasing axial strain. The constitutive relationship of polymer fiber‒reinforced clay could provide satisfactory results. Practical Applications: Polymer fiber mixing increases soil strength and enhances the properties of problematic soils, which makes the problematic soils more valuable for engineering applications. Studies have shown that the fibers in the soil tend to be distributed horizontally after the compaction process. With the anisotropic distribution of fiber orientation considered, the authors established a numerical calculation method for the stress–strain relationship of polymer fiber‒reinforced clay. A major objective of this work was to allow the use of computerized numerical analysis methods when performing mechanical analyses of polymer fiber‒reinforced clay, which avoids the need to conduct a large number of shear tests. In this study, a series of consolidated undrained tests of rubber fiber‒reinforced expansive clay were conducted. With the data collected, the numerical calculation method for the stress–strain relationship of polymer fiber‒reinforced clay was verified, and the numerical results agreed with the test results better. [ABSTRACT FROM AUTHOR]

Biomass-derived substrates have high porosities and hydrophilic properties that match the requirements as substrate in a heat localization solar steam generation (SSG) system. Nevertheless, the irregular branched pattern of the pore structure hinders water flow from bottom to top to immediately replace the evaporating water. Here we report a method to align fiber orientation of cellulose aerogel derived from coir fiber by an electro-assisted method. Specifically, an electric field was applied during the initial phase of gelation process during cellulose aerogel preparation using the dissolution-coagulation route. The vertically aligned fibers in the electro-assisted cellulose aerogel result in higher thermal conductivity (0.246 W m−1 K−1) due to a shorter path of solid for heat flow, smaller thermal tortuosity, than that of the unaligned fibers (0.011 W m−1 K−1). Moreover, they also provide a shorter path of water flow, which is indicated by the higher hydraulic conductivity and the higher water pumping capacity. When used as the substrate for bilayer heat localization SSG system by depositing magnetite nanoparticles as the photothermal material, the vertical and unidirectional fibers can quickly replace the evaporating water resulting in high solar evaporation rate of 1.178 Kg m−2 h−1 under 1 sun irradiation. The electro-assisted cellulose aerogel appears promising as a sustainable and excellent substrate for bilayer SSG system in solar-driven water purification to supply clean water from seawater. [ABSTRACT FROM AUTHOR]

Adding steel fibers to concrete essentially improves its post-crack tensile properties. To determine this experimentally, indirect methods, such as flexural tensile tests, are generally used, which allow only indirect conclusions about the material´s tensile properties. In contrast, direct tensile tests provide the desired result immediately, but are difficult to realize. A key parameter affecting the performance of the SRFC is the orientation of the fibers, which is mainly influenced by the manufacturing process. Typically, when the concrete is cast, the steel fibers align with the edges of the formwork. This is commonly called the wall effect. We address these issues, presenting the setup and results of direct tensile tests on bone shaped specimens with three different steel fiber contents. For each content, a series of specimens with a three-sided formwork (i.e. three-sided wall effect and strong influence on the fiber orientation) and a series with cut-out bones (i.e. one-sided wall effect and less influence on fiber orientation) were fabricated and tested. After these tests, the fiber orientation was determined using an opto-analytical method to quantify the influence of the manufacturing methods on the fiber orientation. Comparing the stress-crack-opening relationships shows that the cut specimens at 0.5 mm crack openings have only about 80% of the tensile strength of three-sided formwork specimens. This effect decreases with larger crack openings and vanishes at about 3 mm crack opening. Finally, a new fiber reinforcement index is defined to correlate observed stress in direct tensile tests to fiber content and orientation in direct tensile tests. [ABSTRACT FROM AUTHOR]

Synthetic fibers deforming over time can be a concern in structural design, particularly in serviceability limit states. Short-term pullout tests are commonly used to predict fiber–matrix interactions, but even in this case, an individualized evaluation of the pullout behavior of single fibers oriented parallel to the load direction may not be sufficient to predict the efficiency of the composite. In the present work, short- and long-term pullout tests were performed with fibers oriented at angles of 15°, 30°, and 45° to the direction of the load to investigate the influence of macro synthetic fibers orientation on fiber–matrix interactions. In short-term tests, optical microscopy images were obtained on the pulled-out fibers to correlate the surface degradation of the fibers with the stress versus strain curves. In quasi-static pullout (short-term), small reductions in pullout strength were observed for all fibers and angles, in addition to an intensive degradation of their surfaces owing to the significant snubbing effect of this type of fiber. In contrast, for the long-term tests, a creep reduction was observed with increasing fiber inclination angle caused by the creep reduction of the fiber due to non-axial loading and additional force components produced by the deviation of the axial force. The parameters of Burgers rheological model were written as a function of the fiber orientation angle, with excellent adjustment to the experimental data. [ABSTRACT FROM AUTHOR]

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Environmental concerns drive the demand for sustainable alternatives to synthetic materials, as high synthetic usage leads to waste and toxic emissions, while natural fibers offer biodegradability, low cost, and lightness. In this study, Mariscus ligularis fiber, developed into bidirectional mats with orientations of ±45°, ±60°, and 0°/90° (A, B, and C), was reinforced with epoxy resin LY556 and hardener HY951. Nine composite laminates with 20, 30, and 40% fiber weight fractions were fabricated using hand lay-up techniques. The mechanical, viscoelastic, thermal, heat distortion temperature (HDT), Vicat softening temperature (VST), and water absorption properties were characterized according to ASTM standards. The mechanical characterization reveals that the 0°/90° laminate with 40% fiber (C40) exhibited the best tensile strength (22.97 MPa) and flexural strength (45.31 MPa). The ±60° laminate with 40% fiber (B40) had the highest impact strength (8 J) and hardness (93.25). The viscoelastic studies indicated that the C40 composite exhibited the most elevated storage modulus (Eʹ) and loss modulus (Eʺ), and the highest glass transition temperature (Tg), signifying strong interfacial bonding and effective stress transfer. The thermal stability of the composites is up to 270 °C. C40 had an HDT of 60.2 °C, a VST of 75.3 °C, and a minimal water absorption of 4.5% after 24 h. The microstructural study confirmed favorable fiber-matrix adhesion and structural properties, making these composites suitable for automotive interior panels and lightweight applications. [ABSTRACT FROM AUTHOR]

Steel fiber-reinforced self-compacting concrete (SCFRC) has been developed in recent decades to overcome the weak tensile performance of traditional concretes. As the flexural strength of SCFRC is dependent on the distribution of steel fibers, a numerical model based on Jeffery's equation was developed in this study for investigating the effects of the concrete flow on the fiber orientation and distribution in SCFRC. This numerical method shows higher computational efficiency than available particle-based methods like SPH and LBM. The influence of casting parameters like casting method, formwork size and casting velocity on the fiber orientation is investigated from the perspective of the flow field of fresh concrete during casting. The simulation results show that the fiber orientation is largely dominated by the concrete flow during the casting process. Importantly, during casting SCFRC beam, fibers tend to be oriented in parallel along the longitudinal direction at the middle section, while they stick up at the end of the formwork due to the upward concrete flow. In addition, the results from parametric studies show that the formwork size and casting method could significantly affect the concrete flow during the casting process, ultimately the orientation of fibers in a SCFRC beam. Furthermore, it indicates that the casting speed needs to be carefully chosen in order to achieve the optimal fiber alignment. [ABSTRACT FROM AUTHOR]

Composite materials are increasingly used in 3D metrology, especially for portable measuring devices such as articulated arm coordinate measuring machines (AACMM), 3D scanners, and ball bars. Their use is justified by their interesting mechanical properties including their low density, good rigidity, and especially their light weight, which makes them ideal for portable devices, that are meant to be often transported by the user. However, due to their complex composition, the characterization of the thermal behavior of composite materials remains complicated compared to standard materials and is nowadays an active research subject. In fact, the coefficient of thermal expansion of composite materials is dependent of the very specific composition of the composite material considered. Hence, it is function of several parameters such as the orientation of the fibers, the fiber volume fraction, the ply sequence, the cooling rate, etc. In the other hand, in 3D metrology, and especially in portable 3D metrology, determining the expansion coefficient of the different part of the measurement devices used is necessary. In fact, the portable measurement machines are often integrated and used directly on the shop floor, where the thermal variations can be important and then heavily impact the measurements results. In some cases, the lack of knowledge of the coefficient of thermal expansion of the composite materials that compose the portable measuring machine can significantly increase the measurement uncertainty. [ABSTRACT FROM AUTHOR]

In this paper, test results for woven ceramic matrix composites (CMCs) based on an oxide matrix and oxide fiber are presented. Stress–strain curves under cyclic loading for different in‐plane fiber orientations as well as strength values for different fiber orientations under tension and compression and under pure shear are presented. Based on the experimental data, a nonlinear damage model is derived which allows to determine the progressive degradation of the elastic moduli and the nonelastic remanent strain in a satisfactory manner. It has been implemented into the finite element code ANSYS and shows excellent convergence behavior. To predict the failure of CMC components, the failure mode concept proposed by Cuntze is extended to include friction effects due to tension and compression on the in‐plane shear failure mode. The predicted failure onset matches the experimental data very well, whereas existing models like the max‐stress or the Tsai–Hill criteria show larger deviations. [ABSTRACT FROM AUTHOR]

The orientation of carbon fibers significantly affects the dynamic properties of unidirectional carbon-based composites (UCBCs), with variations under different static loads. A previous study analyzed changes in the modal parameters of UCBC structures by using the static load influential factor (SLIF). This study introduces a revised SLIF, derived from a simplified formulation that accounts for shifts in resonance frequency and the in-phase relationship between static load and modal response. The revised SLIF is theoretically linked to the modal participation factor in UCBC structures. The dynamic behavior of UCBCs was studied across six modes—four bending and two torsional—using specimens with five carbon fiber orientations, from 0 to 90 degrees. The revised SLIF showed significant effects in two robust specimens, #1 and #2, and an isotropic SUS304 specimen subjected to uniaxial pre-static load, with resonance frequency variations under 0.16%. In contrast, the original SLIF gave negligible results in the fifth mode due to a damping term, which, when multiplied by the resonance frequency, led to an undetectable indicator. Therefore, the revised SLIF more effectively captures the static load's impact on UCBC dynamic behavior compared with the original method. [ABSTRACT FROM AUTHOR]

The influence of fiber orientation on the mechanical behavior of a polymer matrix composite reinforced with natural jute fibers is investigated in this study. Two fiber orientation configurations are examined: the first involves woven fibers aligned in the direction of testing, while the second considers a 45° orientation. The research involves manufacturing composite plates using jute fabric with the mentioned orientations, followed by cutting rectangular specimens for tensile testing to determine which orientation yields superior properties. Displacement fields are measured using a digital image correlation technique, synchronized with load data obtained from a universal testing machine equipped with a load cell to obtain stress–strain curves for each configuration. Results indicate that 0° specimens achieve higher stress but lower strain compared to 45° specimens. This research contributes to understanding the optimal fiber alignment for enhancing the mechanical performance of fiber-reinforced polymer composites. [ABSTRACT FROM AUTHOR]

Fiber orientation is of paramount importance for the design of fiber‐reinforced concrete (FRC) structural elements, because it markedly influences the postcracking properties of such material. For this reason, structural codes introduce orientation factors which aim to correlate the real mechanical properties of the structural element with the ones determined from standard beams. Although the need of considering fiber orientation in design codes is commonly accepted, the orientation factors are still based on a limited number of research studies, raising the need to better determine fiber orientation to improve the current standards and support the design process of FRC elements. In this research, a steel fiber‐reinforced concrete (SFRC) with a hybrid system of macro and microfibers is steered into a broad range of fiber orientations and cast into standard beams. Besides measuring the mechanical performance of these SFRC beams, three different methods for assessing fiber orientation are employed, namely electromagnetic induction, image analysis, and micro‐computed tomography. The comparison between the outcomes of the different methods provides detailed information about the accuracy and suitability of each method, considering the corresponding domain of applicability at structural level. Finally, a critical review of the most common 2D and 3D orientation parameters found in literature is performed, and the equations are adapted to account for the hybrid system of fibers. [ABSTRACT FROM AUTHOR]

Aiming at the merits of highly integrated and free styling of the inner and exterior panels for electric vehicles, an integrated third-generation glass fiber reinforced plastic tailgate (GFRPT) lightweight technology based on structural design, performance optimization, and process manufacturing is proposed. GFRPT preliminary structural data and 3D model are drawn, and modal, stiffness, and concavity resistance simulation analyses are carried out in combination with CAE technology to verify whether the initial data meet the performance requirements. A simulation technique for coupling the injection molding process with part properties is formed by dynamic simulation of glass fiber orientation. Simultaneously, the dimensional deformation is strictly controlled based on the simulation of high and low temperature deformation, combined with the correction of structural profiling and integrated bonding process. Ultimately, through the complete industry chain to develop prototype parts and test verification. The results demonstrate that GFRPT meets all performance requirements, the economic and social benefits are in line with energy saving and emission reduction requirements. The weight reduction rate is 37% and the single sample cost is measured to be reduced. With the gradual maturity of lightweight technology and market, the application ratio of GFRPT will be gradually expanded. [ABSTRACT FROM AUTHOR]

The main objective of the present study is to implement a functionally graded materials (FGM) technique to reduce the hole effect in fiber reinforcement polymers. The tensile and fracture behaviors of conventional and FGM composites containing open holes have been investigated. Open‐hole specimens having different hole sizes have been fabricated using a hand lay‐up technique with different cross‐ply stacking sequences and various numbers of layers to study the open‐hole effect on their tensile strength. On the other hand, a three‐dimensional finite element analysis with the Hashin model was implemented to observe the failure modes along each layer. Experimental and numerical data revealed that the FGM technique enhanced the performance of specimens in the presence of a hole by increasing the fibers around the hole area. Furthermore, the [0°/90°/0°] sequence has more tensile strength than [0°/90°]s and [0°/90°/0°/90°/0°] sequences. It can be concluded that the bearing capacity of cross‐ply laminates is proportionally dependent on the ratio of the number of 0° layers to the number of 90° layers and inversely dependent on the specimen thickness. Highlights: Dense fibers around the open hole improve its strength in laminated composite.The FGM concept has been successfully employed to improve open‐hole strength.The stacking sequence [0°/90°/0°] has better tensile strength than [0°/90°]s.FEA has successfully simulated the FGM concept around the open hole.The open‐hole failure occurred in the same direction as fiber orientation. [ABSTRACT FROM AUTHOR]

This study investigates the hygrothermal aging effect on the tensile and impact behavior of flax/PLA biocomposites. Specimens underwent up to four weeks of conditioning at 40°C in a climate chamber with water. Analysis covered porosity, moisture diffusibility, and transversal microstructure, enabling assessment of tensile strength, tensile modulus, and impact performance in relation to moisture uptake and fiber orientation. The study of tensile properties revealed that at approximately 12% moisture content, stiffness and yield stress decrease, while strength remains constant. Moisture diffusivity is higher in warp and weft yarn directions than the out‐of‐plane direction. Tensile testing at environmental equilibrium moisture reveals greater stiffness in the weft direction, correlated with lower crimp percentage and yarn angle. The main contribution of the paper is the study of the influence of moisture on the impact behavior, the results show that energy absorption capability of flax/PLA biocomposite increases with moisture content. Highlights: Fully biodegradable composite material by heat‐compression molding subjected to hygrothermal aging conditions for up to four weeks.The moisture diffusivity in both the warp and weft yarn directions registered higher values in comparison to the out‐of‐plane direction.Tensile testing at environmental equilibrium moisture revealed that the stiffness in the weft direction presented higher values.At 12% of moisture uptake, the stiffness and yield stress reached their lowest values, while strength remained constant.However, the low‐velocity impact properties of the composites exhibited improvement with moisture. [ABSTRACT FROM AUTHOR]

3D printing of ceramics is a novel technology that allows for the rapid preparation of complex ceramic structures, with potential applications in various industrial fields. However, the high porosity often observed in ceramics prepared via 3D printing can negatively affect their mechanical properties. In this paper, a novel process for manufacturing silicon carbide ceramics reinforced with short carbon fibers (C f /SiC) is proposed. The process employs direct ink writing (DIW) and solid-phase sintering technology, leading to a substantial improvement in the mechanical properties of ceramics and a shorter preparation cycle. Bending properties and fracture toughness of C f /SiC ceramics were evaluated by a series of mechanical tests, including three-point bending and single-edge notched beam tests. The findings showed that the bending strength and fracture toughness of the ceramics were 446.0 MPa and 6.021 MPa•m1/2, respectively. Moreover, a theoretical model was developed to predict the strength of symmetrically distributed laminated beams with different fiber orientation, prepared by varying the printing direction. Simulation results on bending strength from the theoretical model are in good agreement with experimental result with prediction difference less than 11.41 %. [ABSTRACT FROM AUTHOR]

Flax/epoxy composites are recognized as an eco-friendly alternative to synthetic fibers in engineering. Understanding how fiber orientation affects cutting forces and surface characteristics is essential for machining these materials. This study investigates the relationship between fiber orientation and cutting forces (feed, normal, passive) as well as surface roughness in flax/epoxy composites. Results show that fiber orientation significantly impacts cutting forces. Cutting parallel to fibers (0° and 90° orientations) generally requires less force, with 0° needing higher normal force. At 0° orientation, feed force is 46.47 N, normal force is 58.86 N, and passive force is 54.44 N. At 90° orientation, feed force is 56.66 N, normal force is 44.68 N, and passive force is 50.95 N. Oblique orientations (45° and −45°) require higher forces, especially 45°, with the highest normal force of 77.95 N. Surface roughness analysis shows 90° orientation results in the lowest average roughness (Ra) of 10.97 µm but the highest surface roughness (Sa) of 34.25 µm. Conversely, 45° orientation has the highest Ra of 14.2 µm but lower Sa of 22.6 µm. Ra and Sa values for 0° orientation are 13.72 µm and 24.6 µm, and for −45° orientation, they are 12.3 µm and 21.8 µm. Correlation analysis reveals significant relationships between cutting parameters and surface quality, with higher feed rates correlating with smoother surfaces (lower Sa and Ra values). Fiber orientation also significantly influences fluffing defects, with 0° orientation minimizing these defects, while 45° and −45° orientations result in varied patterns. [ABSTRACT FROM AUTHOR]

A general procedure for combining material functions and numerical modeling to predict the orientation of highly filled wood polymer composites (WPCs) in a single screw extrusion and validation thereof is elaborated in this study. Capillary rheometry was used to determine the shear viscosity and wall slip functions as well as the melt density of the biocomposites. The numerical model consisted of a model film die where the melt flow was simulated using a finite element method in the generalized Newtonian constitute equation framework. Fiber orientation was modeled using the Folgar–Tucker approach and included fiber–fiber interaction during the process. Reference extrusion tests were performed on a single screw extruder on the biocomposites. The extrusion setup included two melt pressure transducers that were used to determine the die inlet initial conditions (end of the extruder/die inlet) and provide feedback on the wall slip boundary conditions (pressure discharge along the die). Overall, the pressure error between experiments and simulations was less than 6.5% for all screw speeds investigated in 20 wt. % WPCs. Extrudates were produced, and the wood fiber orientation was estimated based on scanning electron microscopy micrographs and image analysis and compared with the simulations of fiber orientation. We show that the general procedure outlined can be calibrated to predict the overall orientation distribution of wood fiber biocomposites during single screw extrusion. [ABSTRACT FROM AUTHOR]

In this work, a method for measuring tow angles in carbon fiber components, based on the use of a polarized camera, is analyzed from a metrological point of view. Carbon fibers alter the direction of the reflected light's electrical field, so that in each point of the surface of a composite piece, the angle of polarization of reflected light matches the fiber orientation. A statistical analysis of the angle of linear polarization (AoLP) in each pixel of each examined area allows to evaluate the average winding angle. An evaluation of the measurement uncertainty of the method on a cylinder obtained by a filament winding process is carried out, and the result appears adequate for the study of the distribution of angles along the surface of the piece, in order to optimize the process. [ABSTRACT FROM AUTHOR]