Filament Angle Research Articles

Orthotropic mechanical properties of PLA materials fabricated by fused deposition modeling

Polylactic Acid (PLA) sample manufactured by fused deposition modeling (FDM) technique is typically assumed to be transversely isotropic without a thorough examination of its orthotropy in three-dimensional space. This study investigated the mechanical orthotropy of PLA samples with two air gap levels (0 mm and -0.05 mm) and various loading directions. Tensile strength and elastic modulus were experimentally measured and the Hill48 yield model and orthotropic elastic model were calibrated. Results revealed that the anisotropy induced by interlayer bond was more pronounced than that within layer. Introducing a -0.05 mm air gap remarkably reduced voids in printed samples, enhancing the stiffness and strength of tensile samples. It also delayed the transition of fracture modes in intra-layer samples as the filament angle increased from 0° to 90°, which shifted from filament breakage to combined fracture mode and subsequently to interface failure. Despite these improvements, the inherent anisotropy of FDM printed PLA materials remained due to the oriented molecular chains and insufficient chain diffusion. The study emphasizes the importance of orthotropic mechanical models, demonstrating their reliability through calibration with acceptable accuracy.

Comparative investigations on the dynamical responses of ABS and PLA additively-manufactured beams

This study focuses on experimentally analyzing the effects that various filament angles and material types have on the dynamical responses of acrylonitrile butadiene (ABS) and polylactic acid (PLA) based cantilever beams. Three ABS beams are printed with identical geometries and all printing parameters held constant except for the angle of the filament distribution. Next, beams composed of ABS and PLA are printed with identical geometries, printing parameters, and filament orientation. The beams are exposed to free vibration, random vibration, and harmonic excitation to analyze the results for the possible presence of nonlinear behaviors and inconsistencies between the identical beams’ responses. The results between the ABS beams with varying filament orientation are compared to determine possible discrepancies between beams by adjusting filament orientation. It is found that the filament orientation significantly influence the linear and nonlinear properties of these additively-manufactured beams. Then, an experimental comparative analysis is performed between ABS and PLA beams in order to determine the difference in nonlinear behaviors between the two materials. The results show all beams have nonlinear damping and nonlinear softening. It is also demonstrated that beam composed of ABS shows less nonlinear behavior than those printed with PLA. In addition, unlike PLA beams, the results indicate that ABS-based beams are less affected by the presence of multi-stable solutions.

Influence of filament angle orientation on the dynamic characteristics of additively-manufactured beams

Three-dimensional printing provides design flexibility, resulting in shorter product development lifetime as prototypes can be rapidly produced. The most common commercially adopted method for 3D printing is Fused Deposition Modeling (FDM). While the advantages for FDM are apparent, a variation of mechanical, thermal, and dynamic properties arises in FDM components. To gain deeper insight into the dynamical properties of FDM parts, this study investigates a cantilever beam manufactured using a commercially available filament and printer. All printing parameters are kept constant, aside from varying the filament angle, measured from the major axis of the beam. Four cases of varying filament angle orientation are considered to quantify the dynamic response of the systems. Further, duplicates of each beam are manufactured and compared. Experimental results are conducted and analyzed to characterize the dynamical responses of the beams. The free vibration results confirm uncertainty of FDM parts by uncovering inconsistent dynamic properties between identically printed beams. The results of the pseudo-random vibration excitation indicate that varying responses in all system’s axes are observed for varying filament angle orientations. It is also demonstrated that softening nonlinearity for the first mode of vibration is activated for all additively-manufactured beams which is not consistent with typical isotropic responses. Additionally, an explanation on the interaction between the geometric, inertial, and other present nonlinearities is explored and discussed. The outcome of this work shows the strong dependence of additively-manufactured systems to the orientation of the filament angle and their dynamical responses and hence, the need for vibratory characterization for each sample unlike conventional systems.

Identification of the characteristics of helicoidally filament wound tubes using vision systems

As the novel technologies regarding the new generation of fuel transportation and stocking are emerging, the filament winding process appears to be a promising fabrication technique for creating reliable pressure vessels that incorporate a pre-impregnated reinforcing structure. The same method can be applied to any axial symmetric component such as tubes, tow bars and generally tubular composite structures. While the composite filaments are being wound, many factors may influence several parameters that are directly related to the overall mechanical performance of the structure, such as voids in resin-reach areas, variation of the filament angle in values outside of the ones desired, and gaps between subsequent filaments placed together. In the present work, an experimental study is presented in which the potential of a vision system is exploited for detecting such kind of defects that are formed in filament winded tubes. This kind of systems may be used for optical inspection and quality control, as well as for monitoring the component during the process. Gaps between filaments and the winding angle are retrieved after scanning the tubes and several observations are presented about the variation of them throughout the length of the tube.

Solar Energy Driven Membrane Desalination: Experimental Heat Transfer Analysis

In the direct contact membrane distillation (DCMD) system, the temperature polarization due to boundary layer formation limits the system performance. This study presents the experimental results and heat transfer analysis of a DCMD module coupled with a salinity gradient solar pond (SGSP) under three different flow channel configurations. In the first case, the feed and permeate channels were both empty, while in the next two cases, the feed and permeate channels were filled with a porous spacer material. Two different spacer geometries are examined: 1.5 mm thick with a filament angle of 65°, and 2 mm thick with a filament angle of 90°. The study considers only the heat transfer due to conduction by replacing the hydrophobic membrane normally used in a DCMD module with a thin polypropylene sheet so that no mass transfer can occur between the feed and permeate channels. The Reynolds number for all three configurations was found to be between 1000 and 2000, indicating the flow regime was laminar. The flow rate through both the feed and permeate sides was the same, and experiments were conducted for flow rates of 5 L/min and 3 L/min. It has been found that the highest overall heat transfer coefficient was obtained with the spacer of 2 mm thickness and filament angle of 90°.

Design, modeling, optimization, manufacturing and testing of variable-angle filament-wound cylinders

This work demonstrates the potential of manufacturing variable-angle composite cylinders via filament winding (FW), called VAFW. The proposed design strategy allows different filament angles along the axial direction by dividing the cylinder into regions of constant angle called frames. Designs using two, four, or eight frames are herein investigated. A genetic algorithm is applied to optimize each design for maximum axial buckling load. A design with minimum manufacturable filament angle is included in the study. All structures are manufactured and tested under axial compression, with displacements and strains measured by digital image correlation (DIC). The thickness and mid-surface imperfections of the different designs are measured through DIC and used to explain the observed buckling mechanisms. These imperfections are incorporated into a nonlinear numerical model along with a progressive damage analysis. Additionally, a scaling factor is applied on the measured imperfections to enable an imperfection sensitivity study on the proposed designs. The VAFW design shows buckling strength, stiffness, and absorbed energy substantially higher than the constant-angle configuration, attributed to tailored thickness buildup and optimized tow steered angles at particular regions of the cylinder. The experimental and numerical results indicate that VAFW designs can be tailored to postpone buckling so that the material strength can be better exploited. • Innovative manufacturing of Variable-Angle cylinders via Filament Winding: VAFW. • Displacement and strain maps of the VAFW cylinders via DIC. • Optimization using genetic algorithm successfully applied to VAFW cylinders. • Experimental measurement of thickness imperfections for each cylinder design. • Damage modeling with experimental imperfections incorporated in nonlinear FE models.

Surface Characterization of Fracture in Polylactic Acid vs. PLA + Particle (Cu, Al, Graphene) Insertions by 3D Fused Deposition Modeling Technology

Polylactic acid (PLA) is one of the most extensively used biodegradable aliphatic polyester produced from renewable resources, such as corn starch. Due to its qualities, PLA is a leading biomaterial for numerous applications in medicine as well as in industry, replacing conventional petrochemical–based polymers. The purpose of this paper is to highlight the fracture behavior of pure PLA specimens in comparison with PLA particle insertions, (copper, aluminum and Graphene), after evaluation the mechanical properties, as well as the influence of filament angle deposition on these properties. In order to check if the filling density of the specimen influences the ultimate tensile stress (UTS), three different filling percentages (60%, 80%, and 100%) have been chosen in the experimental tests. A hierarchy concerning elongation / fiber heights after tensile testing was done. So, the highest elongation values were for simple PLA (about 4.1%), followed by PLA + Al insertion (3.2%–4%), PLA + graphene insertion (2.6%–4%) and the lowest values being for PLA with copper insertion (1.8%–2.7%). Regarding the fiber heights after fracture, the hierarchy was: the highest values was for PLA, then PLA + Al, PLA + grapheme and PLA + Cu. Finally, a correlation between fracture surfaces appearance and mechanical properties were established, being formulated the mechanism of fracture in according with filament angle deposition. Also, it was proposed a new method of evaluation of the fractured surface by measuring the dimensions of the filaments after printing Fused Deposition Modeling (FDM) and tensile testing.

Effect of the angle of the laid-up filaments on the surfaces on the coefficient of static friction between parts manufactured by extrusion-based 3D printing

Three-dimensional printers, particularly the extrusion-based ones, are driving a global academic, industrial, and social revolution. The accessibility of the technology has allowed a number of enthusiasts and scientists to dedicate efforts to improve the technical properties of the parts produced. However, there is little literature on the measurement of the coefficient of friction, especially the static one, between a pair of printed parts. In this sense, an investigation was carried out in two stages, in which at first the static coefficient of friction was measured, through a simple apparatus based on the concept of the inclined plane, varying the angle of the filaments laid up on the surfaces of the two parts in contact. The parameter was analyzed at three levels—0°, 45°, and 90°—in components manufactured in poly(lactic acid) and poly(ethylene glycol terephthalate). In the second part of the research, a case study was carried out to test and validate the effects of the best and worst friction conditions on the behavior of the insertion force of snap-fit connections. The results obtained show a significant influence of the filament angle in the interaction between two printed parts. Combinations of contact with different angles decrease the static coefficient of friction, while faces with equal angles tend to increase the magnitude of the response, especially if the arrangement of the filaments allows a fit of the surfaces opposite to sliding. The static coefficient of friction of poly(lactic acid) varied from 0.12 to 0.38, while the static coefficient of friction of poly(ethylene glycol terephthalate) varied from 0.13 to 0.21. The responses of the inclined plane test allowed to predict the behavior of the insertion force and plan the design of quick fittings.

Tensile Behavior of PLA and PLA Composite Materials Under Different Printing Parameters

Polylactic acid (PLA) is one of the most extensively used biodegradable aliphatic polyester produced from renewable resources, such as corn starch. Due to its qualities, PLA is a leading biomaterial for numerous applications in medicine as well as in industry, replacing conventional petrochemical - based polymers. The purpose of this paper is to highlight the mechanical properties, such as tensile stress, of pure PLA specimens in comparison with PLA based-composites, with three different added materials in PLA mass: Copper, Aluminum and Graphene, as well as the influence of filament angle deposition on these properties. In order to check if the the filling density of the specimen influences the ultimate tensile stress (UTS), three different filling percentages (60%, 80% and 100%) have been chosen in the experimental tests. In this context, the mechanical characteristics of four different filament types based on PLA material, starting from pure PLA to PLA with Aluminum, Copper or Graphene filler are compared. Understanding and controlling these parameters is essential for the successful use of PLA and PLA-based composites in different areas such as medical applications, sport equipments and light industry.These tests have been performed due to the fact there is a lack of information concerning the mechanical properties. In the scientific literature, such information is only available for expensive printing systems; for open source printers (as those used in these tests), the information is poor and for some new materials, even inexistant. According to the technical specifications, for an expensive printer the cost may exceed 3000 Euros, with a minimum layer resolution of 100 m, this type of printer can reliably reproduce many 3D objects accurately, in quiter conditions.

Reduced strain sensitivity of the critical current of Nb3Sn multifilamentary wires

Strain plays an important role in Nb3Sn multifilamentary wires because critical current depends on it and strain sensitivity of Ic increases at higher magnetic fields. In this paper, a three-dimensional strain data set becomes available by further analysis of an earlier study of the Nb3Sn lattice parameter as a function of uniaxial applied strain at 4.2 K obtained by high-energy x-ray diffraction at the European Synchrotron Radiation Facility at Grenoble. Modeling of the angle dependence of the lattice strain with respect to the wire axis revealed that, under a specific angle, the cubic (undistorted) Nb3Sn unit cell is independent of the applied uniaxial strain. Knowing that the critical current has its maximum for an undistorted unit cell, it is suggested to put superconducting filaments close to this specific angle with the possibility to suppress, or at least reduce, the strain sensitivity of the critical current. For this purpose, a bronze route Nb3Sn wire was manufactured with various twist pitch lengths and with a maximum filament angle up to 38°. For the wire with the shortest twist pitch length (highest filament angle), the critical current at 19 T and 4.2 K is almost independent of the applied strain between 0.1% and 0.5%. This result confirms the theoretical/experimental considerations and opens a new way for the design and manufacture of Nb3Sn wires and magnets.

Spatiotemporal cytoskeleton organizations determine morphogenesis of multicellular trichomes in tomato.

Plant trichomes originate from epidermal cell, forming protective structure from abiotic and biotic stresses. Different from the unicellular trichome in Arabidopsis, tomato trichomes are multicellular structure and can be classified into seven different types based on cell number, shape and the presence of glandular cells. Despite the importance of tomato trichomes in insect resistance, our understanding of the tomato trichome morphogenesis remains elusive. In this study, we quantitatively analyzed morphological traits of trichomes in tomato and further performed live imaging of cytoskeletons in stably transformed lines with actin and microtubule markers. At different developmental stages, two types of cytoskeletons exhibited distinct patterns in different trichome cells, ranging from transverse, spiral to longitudinal. This gradual transition of actin filament angle from basal to top cells could correlate with the spatial expansion mode in different cells. Further genetic screen for aberrant trichome morphology led to the discovery of a number of independent mutations in SCAR/WAVE and ARP2/3 complex, which resulted in actin bundling and distorted trichomes. Disruption of microtubules caused isotropic expansion while abolished actin filaments entirely inhibited axial extension of trichomes, indicating that microtubules and actin filaments may control distinct aspects of trichome cell expansion. Our results shed light on the roles of cytoskeletons in the formation of multicellular structure of tomato trichomes.

Fascin in lamellipodia contributes to cell elasticity by controlling the orientation of filamentous actin.

Fascin, an actin-bundling protein, is present in the filopodia and lamellipodia of growth cones. However, few studies have examined lamellipodial fascin because it is difficult to observe. In this study, we evaluated lamellipodial fascin. We visualized the actin meshwork of lamellipodia in live growth cones by super-resolution microscopy. Fascin was colocalized with the actin meshwork in lamellipodia. Ser39 of fascin is a well-known phosphorylation site that controls the binding of fascin to actin filaments. Fluorescence recovery after photobleaching experiments with confocal microscopy showed that binding of fascin was controlled by phosphorylation of Ser39 in lamellipodia. Moreover, TPA, an agonist of protein kinase C, induced phosphorylation of fascin and dissociation from actin filaments in lamellipodia. Time series images showed that dissociation of fascin from the actin meshwork was induced by TPA. As fascin dissociated from actin filaments, the orientation of the actin filaments became parallel to the leading edge. The angle of actin filaments against the leading edge was changed from 73° to 15°. This decreased the elasticity of the lamellipodia by 40%, as measured by atomic force microscopy. These data suggest that actin bundles made by fascin contribute to elasticity of the growth cone.

Simulation of plate compression behavior of warp-knitted spacer fabrics based on geometry and property parameters

The plate compression property of warp-knitted spacer fabrics greatly determines their industrial application in cushions and mattresses, which can be regulated by the structure and property of spacer filaments of spacer fabrics. To better meet application requirements, this paper detailed a study on the relationships between the geometry and property parameters of spacer filaments and the plate compression property of spacer fabrics. A three-dimensional structure model was firstly developed using the finite element method based on a typical spacer fabric. The model shows a satisfactory prediction of the compression force–strain curve of the spacer fabric compared with the corresponding experimental curve. Consequently, the effects of geometry parameters, including height, diameter, arrangement density and bending angle of spacer filaments, and Young’s modulus of the filaments on the compression behavior of spacer fabrics were investigated using the validated model by adjusting the corresponding geometry and property parameters. The stress nephogram and stress distribution along the filaments at compression strain 0.6 were analyzed to discover the deformation mechanism of spacer filaments under compression. It was found that the spacer fabric with smaller filament height, courser filament diameter, larger bending angle, higher arrangement density and Young’s modulus of filaments had higher compression resistance. This study is useful to optimize the performance of spacer fabrics in design and manufacturing by purposefully tuning the geometry and property parameters.

An experimental study for the characterization of fluid dynamics and heat transport within the spacer-filled channels of membrane distillation modules

The thermo-fluid dynamic behavior of spacer-filled channels for membrane distillation was investigated experimentally. Several different geometry were investigated thanks to customized reference spacers manufactured using a 3D printer. In particular, two sets of experiments were conducted: in the first set, cylindrical filaments were orthogonally arranged and the flow attack angle was made to vary from 0o to 90o; in the second set, the flow attack angle was kept symmetrical and the filament angle was made to vary from 30° to 150°. Each spacer was tested for Reynolds numbers between 200 and 900 in the hot channel, while maintaining a constant temperature difference of 13°C between the hot and the cold channels. Thermochromic Liquid Crystal (TLC) sheets were used for surface temperature measurements. Results showed that, for all spacers, the heat transfer coefficient increases with hot feed flow rate and that the combination of attack angle 45° and filament angle 90° gave the highest heat transfer. Pressure drop measurements showed that spacers could be categorized into two groups relevant to the values of the Darcy friction coefficients (f). One group, associated with spacer designs with filament angles greater than 90°, led to high f values, while the other, associated with filament angles less than 90°, led to moderate f values.

Analysis of the damping property of warp-knitted spacer fabrics under damped free vibration

The main content dealt with in this paper was to carry out a theoretical analysis of the damping property of spacer fabric used as cushion materials. A free vibration test was conducted and the corresponding model was established based on a single-degree-of-freedom (SDOF) system by considering the viscous–elastic behavior of spacer fabric during free vibration. Displacement–time curves of spacer fabric were calculated by a second-order integral of acceleration and time curves recorded by an accelerator sensor. Then, vibration indexes, including the damping ratio, damping coefficient, logarithmic decrement and free vibration period, were featured based on a SDOF model. The experimental results of damping ratio and displacement–time curves were compared with the theoretical results. It indicated that the vibration model was effective to characterize the free vibration of spacer fabric. Moreover, the effects of different structural parameters, including thickness, filament diameter, area density and inclination angle and arrangement of spacer filaments, of the spacer fabric on the damping property were also investigated. This is helpful to better design spacer fabrics with a good damping property.

Study of the vibration transmission property of warp-knitted spacer fabrics under forced sinusoidal excitation vibration

The main content dealt with in this paper was to make a theoretical analysis of the vibration transmission property of spacer fabric as cushion materials. A forced vibration test with sinusoidal excitation was conducted, and the corresponding model of the vibration transmission coefficient was established based on a single-degree-of-freedom system. Experimental and theoretical vibration indexes, including natural frequency and the vibration transmission coefficient, were obtained from experimental and theoretical vibration transmission coefficient–frequency curves, respectively. After comparing theoretical parameters with experimental parameters, we were pleased to find out that their maximum vibration transmission coefficient and natural frequency showed good accordance with each other. Moreover, the effect of different parameters of spacer fabric on vibration transmission properties, including thickness, filament diameter, area density and inclination angle and arrangement of spacer filaments, were investigated, which is helpful to better design spacer fabrics with good vibration transmission.

The effect of feed spacer geometry on membrane performance and concentration polarisation based on 3D CFD simulations

Feed spacers are used in spiral wound reverse osmosis (RO) membrane modules to keep the membrane sheets apart as well as to enhance mixing. They are beneficial to membrane performance but at the expense of additional pressure loss. In this study, four types of feed spacer configurations are investigated, with a total of 20 geometric variations based on commercially available spacers and selected filament angles. The impact of feed spacer design on membrane performance is investigated by means of three-dimensional (3D) computational fluid dynamics (CFD) simulations, where the solution-diffusion model is employed for water and solute transport through RO membranes. Numerical simulation results show that, for the operating and geometric conditions examined, fully woven spacers outperform other spacer configurations in mitigating concentration polarisation (CP). When designed with a mesh angle of 60°, fully woven spacers also deliver the highest water flux, although the associated pressure drops are slightly higher than their nonwoven counterparts. Middle layer geometries with a mesh angle of 30° produce the lowest water flux. On the other hand, spacers with a mesh angle of 90° show the lowest pressure drop among all the filament arrangements examined. Furthermore, the computational model presented here can also be used to predict membrane performance for a given feed spacer type and geometry.

Theoretical Considerations of Pressure Drop and Mass Transfer of Gas Flow in Spiral Wound Membrane Modules

In this work we give the preliminary results of the development of two reliable correlations for the calculation of the friction and mass transfer coefficients for the gas transfer through spiral wound membrane modules. The mass transfer coefficient which allows determining the polarization phenomenon was taken in consideration through the calculation of the Sherwood number near the surface of the membranes. Both correlations take in consideration the inclination angle of transversal and longitudinal filaments of grids in spacers. They allow a good prediction of the pressure drop, friction coefficient and the mass transfer in spiral modules for gas flow when compared with experimental results obtained in a previous work reported in the literature.

CFD simulations of the fluid flow behavior in a spacer-filled membrane module

In this study, the effects of the angles of spacer filaments and the different feed Reynolds number on the fluid flow behavior have been investigated. Three-dimensional computational fluid dynamics (CFD) study is carried out for fluid flow through rectangular channels within different angles (30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, respectively) between two filaments of spacer for membrane modules. The results show that the feed Reynolds number and the angles of spacer filaments have an important influence on pressure drop. While the feed Reynolds number is fixed, the optimal angle of spacer should be between 80° to 90°, because the pressure drop is not only relatively small, but also high flow rate region expanded significantly with the increase of the angles between 80° to 90°.The Contours of velocities and change of the average shear stress with the different angle of spacer filaments confirm the conclusion.

Interaction of a plane progressive sound wave with anisotropic cylindrical shells

An exact analysis based on the wave function expansion is carried out to study the scattering of a plane harmonic acoustic wave incident at an arbitrary angle upon an arbitrarily thick helically filament-wound (anisotropic) cylindrical shell submerged in and filled with compressible ideal fluids. Using the laminated approximation method, a modal state equation with variable coefficients is set up in terms of appropriate displacement and stress functions and their cylindrical harmonics to present an analytical solution based on the three-dimensional exact equations of anisotropic elasticity. Taylor’s expansion theorem is then employed to obtain the solution to the modal state equation, ultimately leading to calculation of a transfer matrix. Following the classic acoustic resonance scattering theory (RST), the scattered field and response to surface waves are determined by constructing the partial waves and obtaining the background (non-resonance) and resonance components from it. The solution is particularly used for the isolation and identification of excited resonances of an air-filled and water submerged Graphite/Epoxy cylindrical shell as the circumnavigating helically propagating waves. In addition, the sensitivity of resonances associated with various modes of wave propagation appearing in the backscattered amplitude to the perturbation in the material’s elastic constants is examined. Furthermore, non-axisymmetric dynamic behavior of the anisotropic shell is illustrated by analyzing the directivity pattern associated to the angular distribution of the far-field form function amplitude. The effects of winding angle of filaments and the shell wall-thickness on the frequency response of the shell are also investigated. For verification, the wave propagation characteristics of the anisotropic shell (which have been extracted from the main body of the solution) and the far-field form function amplitude of a limiting case are considered and fair agreement with the solutions available in the literature are established.