Multiscale modeling based failure criterion of injection molded SFRP composites considering skin-core-skin layered microstructure and variable parameters

The stress in polyphenylene sulfide (PPS) resin reinforced by glass fibers of 26 mass% was measured by the diffraction method using synchrotron with energy of 18 keV. The stress in the matrix was determined by the sin2ψ method with iso-inclination optics of transmitted X-ray diffractions. Tensile coupon specimens were cut from the skin-layer of injection molded plates in three directions, parallel, perpendicular and 45°, to the molding direction. The matrix stresses in the loading and transverse directions of specimens were measured under several uniaxial applied stresses. They changed proportionally to the applied stress. The proportional constants of the matrix stresses to the applied stress were determined, and named the stress-partitioning coefficients. The elastic constant and the matrix stress of the composite were calculated theoretically using micromechanics for two cases of fiber orientation: unidirectional (UD) and varied orientation distribution (VD). Fiber orientation tensor was determined from microscopic measurement of the cross-sectional shape distribution of fibers. Compared with the calculation based on UD fiber orientation, the analytical values based on micromechanics considering the variation in fiber orientation are closer to experimental values of elastic constants and stress-partitioning coefficients.

This paper describes composite materials tensile testing of electric car body material. The UNNES electric car body must be developed using a high strength and lightweight material. A fiber-reinforced plastic composite is widely used for the concerned objective. Selection of the type of composites, variations in fiber orientation, and the number of fiber layers will affect the tensile strength of the material. Composite materials use Carbon-fiber-reinforced plastics (CFRPs) and glass-fiber-reinforced plastics (GFRPs) variation to the fiber areal weight, variations in fiber orientation and the number of fiber layers. The CFRPs areal weight consists of 230 gsm and 400 gsm. The GFRPsareal weight consists of 400 gsm and 600 gsm. Fibre orientationsconsist of 0° and 45°. Number of fiber layers consists of one layer and two layers. Various variations were then tested to figure out their tensile to get ultimate tensile strength of materials. Standard test method for tensile test was conducted using ASTM D3039. Tensile specimen geometry used a type of balanced and symmetric fiber orientation, with 25mm in width, 250 mm in length, and 2.5 mm in thickness. The result shows that the more fiber areal weight and the layer number were used, the more its tensile strength would increase, beside it increased the ultimate tensile strength of the material for both glass and carbon fiber with 0o and 45o fiber arientation. Fiber plain wave with 45o has greater tensile strength compared to any other variation.

This paper presents a report about work in progress of research on the influence of the flow of SCFRC on the fiber orientations. Mechanical properties of the short steel fiber reinforced cementitious materials mostly depend on the fiber orientation and spatial dispersion. Many studies have shown that it is possible to achieve the desired fiber orientation by optimizing the parameters of rheological properties or the casting process. In order to improve the key mechanical properties, multiple statistical experiments with various factors are needed. This paper analyzes the influence of casting velocity and formwork surface quality on the fiber distribution and orientation. A suitable technique for our method was to replace Steel Fiber Reinforced Self-Compacting Concrete (SFRSCC) by a transparent polymer with similar rheological properties as SFRSCC. Preliminary analysis of the experimental results shows that the fibers tend to orient mostly perpendicular to the flow direction and turn their orientation longitudinally near the walls. Experiments showed that the fiber spatial distribution was affected by the casting velocity. Faster casting velocities provided more preferable homogeneous distribution. Moreover, the roughness of the bottom of the formwork demonstrated some influence on the fiber orientations but no significant impact on the spatial dispersion. In addition, we used the image analysis method to estimate fiber orientation and distribution.

This paper assesses the effectiveness of including variable thickness and fiber orientation characteristics of the skeletal muscle layer in calculations relating epicardial and torso potentials. A realistic model of a canine torso which includes extensive detail about skeletal muscle layer thickness and fiber orientation is compared with two other uniformly anisotropic models: one of constant thickness and the other of variable thickness. First, transfer coefficients are calculated from the model data. Then torso potentials for each model are calculated from the transfer coefficients and measured epicardial potentials. The comparison of calculated and observed torso potentials indicates that a simple model consisting of a uniformly anisotropic skeletal muscle layer of 1.0-1.5 cm constant thickness significantly improves the model. However, if photographic slices of the canine torso are used to introduce more detailed data about the variation in skeletal muscle thickness and fiber orientation into the model, the agreement and between calculated and measured torso potentials decreased, although a finite element mesh of over 5000 nodes was used to describe the skeletal muscle in the more detailed model. One source of error increase was considered to be due to numerical discretization and could be reduced with a much finer mesh or by utilizing higher order polynomials to represent the potential distribution within each finite element. However, the results presented in this paper show that high precision computation (64-bit word length) on the mainframe IBM 3081 with an attached FPS-164 gives a slow rate of improvement with reduced discretization intervals and that utilizing higher order polynomials within each finite element gives an even slower rate of improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Tensile fatigue behaviour of Ultra-High Performance Fibre Reinforced Concrete combined with steel rebars (R-UHPFRC)

Short carbon fiber-reinforced polymer composites are widely used in polymer extrusion additive manufacturing (AM), including large-area additive manufacturing (LAAM), due to their enhanced mechanical properties as compared to neat polymers. However, the mechanical properties of these composites depend on microstructural characteristics, including fibers and micro-voids, which are determined during processing. In this work, the correlation between fibers and micro-voids within the microstructure of LAAM polymer composites throughout various processing stages of short carbon fiber-reinforced acrylonitrile butadiene styrene (SCF/ABS) is investigated. The processing stages considered here include the incoming pellets, a single freely extruded strand, a single regularly deposited bead, and a single regularly deposited bead pressed by a mechanical roller. A high-resolution X-ray micro-computed tomography (µCT) system is employed to characterize the microstructural features in terms of the fibers (volume fraction, fiber orientation tensor) and micro-voids (volume fraction, sphericity) in the SCF/ABS samples. The results indicate that micro-voids exist within the microstructure of the SCF/ABS composite in all four stages considered here and that the micro-void volume fraction and micro-void sphericity vary among the test samples. Moreover, the results show a considerable variation in fiber orientation and fiber volume fraction within the microstructure throughout all the stages considered; however, all the samples show the highest alignment in the extrusion/print direction. Furthermore, a correlation is identified between the fiber orientation and the micro-void volume fraction within samples from all four stages considered here. This finding suggests that fibers tend to align more in the extrusion/print direction in regions with less micro-void content.

The utilization of coconut fiber currently is limited to making brooms or for burning, necessitating further applications. One of these applications is its use as a reinforcement in composites, enhancing utility value and environmental friendliness. This study focuses on crafting composites from coconut fiber with variations in fiber orientation: random, 0°, and 45°.Tensile testing results reveal that the random fiber orientation variation exhibits the best performance, with a stress of 27.30 MPa, attributed to higher density. The 45° fiber orientation variation has the lowest stress (24.23 MPa) due to a lower fiber count. In bending tests, the random fiber orientation variation again performs the best, with a bending stress of 120 MPa, attributed to its high density that strengthens the structure. The 0° fiber orientation has the lowest bending stress (88.59 MPa) due to lower fiber density.Overall, utilizing coconut fiber as reinforcement in composites shows promising positive outcomes, with the random fiber orientation variation providing the best mechanical performance. This endeavor holds the potential to enhance the economic and ecological value of coconut fiber.Keywords: Composite, fiber, coconut, tensile, bending

Cell-specific responses to changes in size-scale and orientation of architectural cues in polymeric scaffolds: Insights from human mesenchymal stem cells and endothelial cells.

This paper presents a novel fiber spraying process for the manufacturing of short fiber bundle‐reinforced Nextel™ 610/Al 2 O 3 ‐ZrO 2 oxide fiber composites (SF‐OFC) and its characterization. First, the influence of varying fiber lengths (7, 14, and 28 mm, continuous fibers) and fiber orientations (unidirectional 0°, quasi‐isotropic, ±45°) was investigated using hand‐laid SF‐OFC. Due to the weak matrix, the hand‐laid material exhibited a strongly fiber‐dominated material behavior, that is, variations in fiber length and orientation had a strong influence on the material properties. Second, the automated sprayed SF‐OFC, however, exhibited a random orientation of the fiber bundles, which resulted in in‐plane isotropic material properties. Average bending strengths of up to 177 MPa, strains of .39%, and a quasi‐ductile fracture behavior were achieved. The strain was, therefore, in the range of fabric‐reinforced OFC. While the bending strength of the SF‐OFC was somewhat lower than that of fabric‐reinforced OFC with the fiber orientation parallel to the loading direction, it was more than two times higher than the strength in 45° direction relative to the fabric reinforcement. Combined with good drapability and lower material costs compared to fabric‐reinforced OFC, SF‐OFC is, therefore, a promising material for industrial applications.

Predicting the modulus of short fiber‐reinforced composites is complicated by simultaneous variations in fiber length, orientation, and volume fraction during processing. This work refines the classical modified rule of mixtures (MROM) by introducing two concentration‐dependent weighting functions, and , which capture the evolution of effective fiber length, fiber‐fiber interactions, fiber orientation, and loading‐angle effects. A microstructural efficiency coefficient is further incorporated to describe reinforcement degradation from dilute to crowded fiber conditions. The model was validated using ethylene‐vinyl acetate/short carbon fiber composites with fiber volume fractions of 1.37%–16.80%. Young's modulus measured at loading angles of 0°, 45°, and 90° showed excellent agreement with predictions, with the refined formulation outperforming the classical MROM, particularly at higher loading angles. Overall, the refined framework provides a compact and physically grounded framework for accurately predicting stiffness and supports the design and optimization of short fiber‐reinforced polymer systems.

Recent advancements in 3D printing involve reinforcing the polymer matrix with high-strength fibers offer improved mechanical properties over unreinforced polymeric materials. The fiber-reinforcement offers a great potential to customize fiber-reinforced 3D printed polymer composites for complex shapes and high-performance parts for diverse end use applications. The advance capabilities also allow to vary the 3D printed composite weight without compromising the mechanical properties. The aim of this research was to investigate unique macrostructures of 3D printed samples developed by varying the printing parameters, and their influence on the tensile behavior. Samples developed for this study comprised of nylon matrix reinforced with continuous fiberglass with three varying fiber orientations and four different infill geometries. Tensile properties of the unreinforced and reinforced 3D printed samples were evaluated to investigate the impact of fiber orientation and infill geometries and further benchmarked with traditional 3D orthogonal woven (3DOW) composites. The results indicated that the tensile properties due to fiber orientation mainly dictated the tensile properties more than the cellular structure. The analyses from this study showed that the macrostructure (hence tensile properties) of 3D printed specimens were directly related to the printing parameters that include fiber amount and orientation, void formation and the bonding between individual raster/layers.

In this study, effects of variations in the fiber orientation for GFRP tension test on strength and temperature distributions were experimentally investigated. The temperature measurement method for test specimen was proposed in an IR thermography. Lock-in method, which is one of technique in IR thermography to measure the temperature of specimen as a function of time, was utilized to monitor changes in the temperature distribution during crack propagation process. At the maximum stress point, the temperature was significantly increased. A specimen with shorter fracture time showed an abrupt increment of temperature at the maximum stress point. Specimen with longer fracture time displayed increment of temperature after the maximum stress point. Tension strength of 0° direction of GFRP increased being proportional the fiber content and fiber orientation function as a change from isotropy to anisotropy. But, the tension strength of 90° direction by separation of fiber filament decreased when a tension load is imposed for width direction of reinforcement fiber length direction.

The study for strength calculation of one way fiber-reinforced composites and the study measuring precisely fiber orientation distribution were presented. However, because the DB that can predict mechanical properties of composite material and fiber orientation distribution by the fiber content ratio was not constructed, we need the systematic study for that. Therefore, in this study, we investigated what effect the fiber content ratio and fiber orientation distribution have on the strength of composite sheet after making fiber reinforced polymeric composite sheet by changing fiber orientation distribution with the fiber content ratio. The result of this study will become a guide to design data of the most suitable parts design or fiber reinforced polymeric composite sheet that uses the fiber reinforced polymeric composite sheet in industry spot, because it was conducted in terms of developing products. We studied the effect the fiber orientation distribution has on tensile strength of fiber reinforced polymeric composite material and achieved this results below. We can say that the increasing range of the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation is getting wider as the fiber content ratio increases. It shows that the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation 90° is similar with the value of polypropylene’s intensity when fiber orientation function is J= 0.7, regardless of the fiber content ratio. Tensile strength of fiber reinforced polymeric composite is affected by the fiber orientation distribution more than by the fiber content ratio.

The effect of material flow on the stress analysis of an SMC component

Abnormal passive stiffness of the heart muscle (myocardium) is evident in the pathophysiology of several cardiovascular diseases, making it an important indicator of heart health. Recent advancements in cardiac imaging and biophysical modeling now enable more effective evaluation of this biomarker. Estimating passive myocardial stiffness can be accomplished through an MRI-based approach that requires comprehensive subject-specific input data. This includes the gross cardiac geometry (e.g. from conventional cine imaging), regional diastolic kinematics (e.g. from tagged MRI), microstructural configuration (e.g. from diffusion tensor imaging), and ventricular diastolic pressure, whether invasively measured or non-invasively estimated. Despite the progress in cardiac biomechanics simulations, developing a framework to integrate multiphase and multimodal cardiac MRI data for estimating passive myocardial stiffness has remained a challenge. Moreover, the sensitivity of estimated passive myocardial stiffness to input data has not been fully explored. This study aims to: (1) develop a framework for integrating subject-specific in vivo MRI data into in silico left ventricular finite element models to estimate passive myocardial stiffness, (2) apply the framework to estimate the passive myocardial stiffness of multiple healthy subjects under assumed filling pressure, and (3) assess the sensitivity of these estimates to loading conditions and myofiber orientations. This work contributes toward the establishment of a range of reference values for material parameters of passive myocardium in healthy human subjects. Notably, in this study, beat-to-beat variation in left ventricular end-diastolic pressure was found to have a greater influence on passive myocardial material parameter estimation than variation in fiber orientation.