Flexure Modules Research Articles

Design and Control of Modular Compliant XY Positioning stage

The modular design and controller implementation of compliant XY stage having large motion range are presented.The design involves symmetric parallel kinematic configuration using compound parallelogram flexure module (CPM) with input-output decoupling properties. The architectural parameters are determined based on the performance metrics such as stiffness, resonance frequency and motion range etc. The FEA simulation predicts the range of motion of 12 mm along each working axes.A prototype is developed to assess the performances of the stage. The results exhibit the small deviation between the two working axes which reflects the better decoupled motions.The PID controller is implemented to achieve the accuracy of positioning with submicron resolution.

Polypropylene Composites Reinforced with Lignocellulose Nanocrystals of Corncob: Thermal and Mechanical Properties

Composites based on recycled polypropylene (PP) reinforced with cellulose nanocrystals whit lignin corncob were prepared. The effect of the ratio composites prepared via a compression molding process on the mechanical and thermal properties was analyzed. Corncobs is a little-used agroindustrial residue with a high cellulose content. The corncob was milled and then delignified via the organosolve process in order to get the cellulose unbleached. An acid hydrolysis process was then carried out to obtain lignocellulose nanocrystals (LCNCs). Subsequently, LCNC/PP composites were obtained via termocompression molding using different concentrations of LCNC (0, 0.5, 1 and 2% by weight) previously mixed via extrusion. The residual lignin present in the LCNCs improved the compatibility between the reinforcement and the PP matrix. This was evidenced by the increase in mechanical properties and the stabilization of thermal properties. The results of the mechanical tests showed that the LCNC increases the tensile and flexural modules and strength with respect to neat PP. Composites with 2% of LCNC showed an increase of 36% and 43% in modulus and tensile strength, respectively, while the flexural modulus and strength increased by 7.6%. By using reinforcements of natural and residual origin (corncob) and improving the properties of recycled polymers, their reuse will increase, and this can lead to reducing waste in the environment.

Characterisation of Nanoclay and Spelt Husk Microfiller-Modified Polypropylene Composites.

Current research is devoted to the investigation of spelt husk (SH) and nanoclay-modified compatibilised polypropylene (PP) binary and ternary composites for injection-moulding applications. PP composites were obtained using twin-screw extrusion. The content of mechanically milled SH microfiller with aspect ratio within 2 and 6 was fixed at 40 wt.%, whereas the amount of nanoclay functional filler in the polypropylene matrix was changed in the range from 0.5 to 5 wt.%. Nanoclay filler was introduced in the polypropylene matrix either in the form of nanoclay powder (C) or as a masterbatch (M). Regular distribution of the clay nanofiller within the polymer matrix has been observed, disregarding its form and concentration. The effects of the individual or combined addition of SH microreinforcement and nanoclay fillers on the rheological, mechanical, calorimetric, and thermal properties of the developed PP composites were investigated. It is revealed that the addition of the nanoclay fillers insignificantly influences the viscosity of both PP nanocomposites and hybrid composites with SH. Additionally, for PP nanocomposites, remarkable increases in tensile and flexural modules and strength are observed by maintaining considerable ultimate deformations, mainly in the case of M-containing systems. Concomitantly, because of the addition of the nanoclay filler, the improvement in thermal stability of PP nanocomposites and PP hybrid composites with SH is observed. As a result of SH addition, considerable increases in tensile and flexural modules are also observed. Results of the research demonstrate the potential of the use of natural materials (agricultural residues and clay minerals) for the development of PP composites with increased stiffness and thermal properties.

Redeemable environmental damage by recycling of industrial discarded and virgin glass fiber mats in hybrid composites—An exploratory investigation

AbstractThe fiber industry develops materials with good physical and mechanical characteristics, but it also generates a lot of waste that is difficult to degrade. Glass fibers can be extracted from waste glass fiber reinforced polymers because of advancements in grinding and sorting technologies. The objective of the current paper is to use waste glass fiber along with new woven glass fiber mat in structural application. Composites were manufactured using the hand layup method using virgin and discorded woven glass fibermats with different fiber weight fractions such as 10%, 20%, 30%, and 40%. Composites were then investigated for the influence of the recycled fiber on mechanical and vibration behavior using appropriate tests. Theoretical models were used to predict the mechanical behavior of the composites. Scanning electron microscopic technique was used to analyze the failure surface morphology of the composite specimen. Results portrayed that the composites with 40 wt% of new woven glass fiber mats exhibited better mechanical strength (tensile and flexural strengths and modules of 243 MPa, 1752 MPa, and 1244 MPa, 946 MPa, impact strength of 12.13 J). The combined effect of new and recycled glass fiber composites exhibited tensile and flexural strength of 211 MPa and 1734 MPa, modulus of 1222 MPa and 925.7 MPa, impact strength of 10.43 J. The natural frequency of both composites was very close to all other volume fractions. The theoretical model also ended up with the same result and the margin of difference between predicted results and experimental results was very minimum.

PET의 난연 특성 및 기계적 특성에 대한 Boehmite와 Vermiculite의 영향

The effects of boehmite (BM) and vermiculite (VMT) on flame retardancy, combustion behavior and thermal degradation behaviors of polyethylene terephthalate (PET), BM/PET, and VMT/BM/PET composites were investigated by methods of limited oxygen index (LOI) measurement, vertical burning test, cone calorimeter test and thermogravimetry analysis (TG). The results showed that BM can effectively flame retardancy PET, when 12% BM was added into PET, 12-BM/PET composite possessed LOI value of 32.4% and V0 rating (3.2 mm) in UL-94 test. The flame retardancy, thermal stability and combustion behavior data of 2.5-VMT/BM/PET composite were better than that of 12-BM/PET composite, indicates that appropriate amounts of VMT and BM in PET had synergistic flame-retardant effects. Replace part of BM with VMT, with the increased of VMT substitution amount, the flexural strengths and tensile strengths of VMT/BM/PET composites increased at first, and then decreased, the flexural modules was increased and the notched izod impact strength was decreased.

Synthesis of Bismuth-Containing Polymer Films with High Refractive Index and X-ray Shielding Property by Radical Polymerization of Styrylbismuthine Derivatives.

Highly refractive and X-ray shielding polymer films were prepared by bulk radical copolymerization of diphenylstyrylbismuthine (MStBi) with tristyrylbismuthine (TStBi). For example, a yellow transparent film was obtained by copolymerization of MStBi and TStBi in a ratio of 70:30 (w/w). The refractive index (nD) and radiopacity of the film of these polymers are 1.72 and 1.60 μm-Al/μm-polymer, respectively. These properties are higher than those of the reported bismuth-containing polymers. The thermal stability and flexural module of the polymer films were controllable by the feed ratio of TStBi. The polymer films also exhibited high surface hardness and solvent resistance due to the rigid and cross-linked structure. The chemical and thermal stability and higher refractive index and radiopacity of the polymers suggest the potential applications for X-ray shielding of optical materials with high refractive indices.

Comparison of different surface treatment methods on flexural strength and elasticity modules of quartz and glass fiber-based posts: A narrative review.

Evaluating the effect of different surface treatment methods on flexural strength (FS) and elasticity modules (EM) related to fiber posts is very important. The main purpose of this study was to evaluate the effect of different surface treatment methods on FS and EM of quartz and glass fiber-based posts in the form of a narrative review study. To conduct this study, all studies related to the subject under discussion during the years 2022-2000 by systematic search in internationally available databases, including Web of Science, Science Direct, Scopus, PubMed, and Google Scholar, were checked out. Finally, completely relevant studies were selected to investigate the main objective. The results showed that before surface preparation, FS and elasticity coefficient (EC) of quartz fiber-based posts were higher than glass fiber. According to the results of some previous studies, surface preparation of glass and quartz fiber posts by laser and 10% hydrogen peroxide has no effect on their FS and elasticity. Findings of some other studies showed that the laser method than air abrasion can be a more suitable method for preparing the surface of fiber posts before the bonding process. In some other studies, it was reported that the Airborne-particle abrasion (Al2O3) method produced a higher amount of FS than the laser. Based on the results of previous similar studies, it can be concluded that the results of previous studies are very contradictory, and therefore, it is not possible to provide a completely superior surface treatment method to increase flexural strength. The amount of flexural strength depends mainly on the intrinsic properties of the fiber post.

CAD/CAM Polimerlerinin (PEEK/PMMA) ve Geleneksel PMMA Materyallerinin Bazı Mekanik Özelliklerinin Değerlendirilmesi: İn Vitro Çalışma

Objective: The present study aims to investigate the mechanical properties of base materials [polymethyl methacrylate (PMMA)/polyether ether ketone (PEEK)] fabricated with computeraided design/computer-aided manufacturing (CAD/CAM) and heatpolymerized conventional base materials. Material and Methods: Two different base polymers milled with CAD/CAM (Yamahachi PMMA Disk and Juvora Dental Disk PEEK) and heat-polymerized acrylic resin (Meliodent PMMA) were used in this study. A total of 120 specimens were prepared with 10 specimens in each subgroup of the test materials. Half of the test specimens were stored in distilled water, while the other half were subjected to a thermal cycle. After the thermal cycle, the flexural strength, elasticity module, and, surface hardness of all test specimens was evaluated. The Mann-Whitney U and Kruskal-Wallis tests were used in the analysis of the data. Results: According to the findings of flexural strength and elasticity module of the test specimens, the highest to lowest value ranking was as follows: CAD/CAM PEEK>CAD/CAM PMMA>heat-polymerized PMMA. In the PMMA group produced with CAD/CAM, surface hardness values were significantly higher in the thermocycle applied test specimens compared to those stored in distilled water (p<0.001). Conclusion: CAD/CAM PMMA and PEEK materials were compared with the heat-polymerized test specimens found to show better mechanical properties.

Flexural wave parameter measurements of viscoelastic panels using a laser doppler correlation vibrometry

Characterizing broadband dynamic properties of viscoelastic panel materials represents a challenging task, particularly when the frequency band of interest needs to be extended toward low frequency range. This work applies a laser Doppler vibrometer in measuring flexural wave properties of the viscoelastic panel materials. The measurement relies on a time-domain broadband correlation technique which experimentally measures impulse responses at two points radially away from a flexural wave exciter. Using reasonable sized panel samples, boundary conditions of the measurements present insignificant obstacles towards high frequency range, since a time-domain windowing facilitates extraction of direct wave components. While boundary reflections will still obscure measurement results towards low frequencies. This work examines a possible mitigation approach by rotating the sample panel, the coherence of direct wave pulses measured equidistant from the exciter and the lack thereof disturbing boundary reflections enables largely removing the undesirable reflections. In this way angular averaging significantly reduces boundary reflections. This paper discusses experimental investigations on the characterization method of flexural wave parameters including wave speed, flexural modules and loss factor.

Durability of Sustainable Ceramics Produced by Alkaline Activation of Clay Brick Residue

Alkali-activated materials (AAMs) were produced using residues from the red ceramic industry as a precursor, and sodium hydroxide (NaOH), potassium hydroxide (KOH), and sodium silicate (Na2SiO3) as alkaline activators. The effect of activators and curing conditions on physical-mechanical properties and durability were evaluated. The processing parameters (amount of water and consistency index) and the activation conditions (the activator contents and curing temperature) were defined based on an experimental design getting the flexural rupture module as the response. The durability behavior was evaluated by natural aging, accelerated aging (simulated rain test), exposure to the marine environment (salt fog), and acidic environments (HCl and H2SO4). The results showed that the NaOH- and KOH-activated samples exhibited inferior mechanical behavior than those activated with Na2SiO3. In the durability studies, due to leaching, there was a decrease in mechanical strength when samples are subjected to aggressive exposure conditions. However, the strength values are still higher than the minimum indicated for traditional ceramic applications.

Effect of recycled aggregate on behaviour of tied reinforced fibrous rectangular short columns

This study focuses on studying the behaviour of fibrous rectangular short columns (tied reinforced) using recycled coarse aggregate (f’c, ft, Ec, fr) is found by using recycled aggregates with comparison to normal aggregates with and without using steel fibres. For this purpose, five (5) tied short columns were cast (150 mm length x 150 mm width x 600mm height) with different percentage of recycled coarse aggregate (0%, 50%, 100%) and different percentage of steel fibre (0%, 0.5% and 1%). The study resulted that when adding the 50% normal aggregates with 50% recycled aggregates, a decrease of (10%, 18%, 30% and 22%) (compressive strength, splitting tensile strength, flexural strength and elasticity module) respectively was observed, when replacing the100% normal aggregates with 100% recycled aggregates, a decrease of (30%, 35%, 58% and 63%) (Compressive strength f’c, splitting tensile strength ft, flexural strength fr and elasticity module Ec) respectively was observed. The changes in the compressive strength by adding steel fibres to the RAC by a proportion (0.5%, 1 %) resulted in a significant increase of about (14 %, 35 %), respectively.

Carbon fiber/epoxy resin/α-aluminum oxide nanocomposites; fabrication, mechanical and thermal analysis

A composite is a material having two or more components with diverse chemical or physical properties. Due to the special feature of the composites, the use of various materials and research in their field is developing. By considering the above points, in this work a series of the nanocomposites from α-Al2O3 nanoparticles (α-Al2O3 NPs, at 2, 5, and 10% by wt), carbon fibers (CF), and epoxy resin were fabricated and their thermal and mechanical performance were evaluated. The dispersion mode of α-Al2O3 NPs in the composite structure was evaluated through a field emission scanning electron microscope (FE-SEM). The FE-SEM analysis revealed that the α-Al2O3 NPs and CF were homogeneously dispersed in the epoxy matrix and the morphology of α-Al2O3 NPs–CF/epoxy composites is uniform. The results of the mechanical tests exhibited that the flexural strength and module of E-40 (epoxy resin: carbon fiber: α-Al2O3, 65:25:10) were at their highest levels; 295 MPa and 11,917 MPa, respectively. For flexural strength and module, improvements were made by 95.5% and 91.8% in comparison with the samples in the absence of NPs. The highest tensile strength was obtained for E-30 (epoxy resin: carbon fiber: α-Al2O3, 70:25:5); 341 MPa. There is a 24% enhancement in tensile strength as compression by a sample without NPs. Accordingly, we can conclude that the addition of α-Al2O3 NPs in composite structures has significantly affected the mechanical response. However, the thermal analysis was illustrated as an inverse trend by the addition of NPs. Therefore, the performance of experimental tests revealed that the composite with the required feature could be prepared based on the obtained results.

Variable Stiffness Devices Using Fiber Jamming for Application in Soft Robotics and Wearable Haptics.

Variable stiffness actuation has applications in a wide range of fields, including wearable haptics, soft robots, and minimally invasive surgical devices. There have been numerous design approaches to control and tune stiffness and rigidity; however, most have relatively low specific load-carrying capacities (especially for flexural loads) in the most rigid state that restricts their use in small or slender devices. In this article, we present an approach to the design of slender, high flexural stiffness modules based on the principle of fiber jamming. The proposed fiber jamming modules (FJMs) consist of axially packed fibers in an airtight envelope that transition from a flexible to a rigid beam when a vacuum is created inside the envelope. This FJM can provide the flexural stiffness of up to eight times that of a particle jamming module in the rigid state. Unlike layer jamming modules, the design of FJMs further allows them to control stiffness while bending in space. We present an analytical model to guide the parameter choices for the design of fiber jamming devices. Finally, we demonstrate applications of FJMs, including as a versatile tool, as part of a kinesthetic force feedback haptic glove and as a programmable structure.

Layup Design Optimization for E-glass Woven Roving Fabric Reinforced Polyester Composite Laminates Produced by VARTM

In this study, a satisfactory number of actual test results were used to optimize the stacking sequence design of bidirectional glass-woven fabrics in polyester composite laminates. In optimization, parameters such as glass-woven fabrics with five different areal weights, stacking sequence, number of plies (PLY), and off-axis fiber directions (DEG) were taken as input factors. Values such as tensile strength (UTS) and flexural strength (UFS), mechanical anisotropy factors (AFs), and resin permeability coefficient of stacked glass-fabrics were taken as output responses. In this study, a laboratory-scale vacuum assisted resin transfer molding (VARTM) process was established. Composite laminates with sixteen different stacking and six different number of plies are produced. Mechanical properties such as tensile and three-point flexure have been tested for the composite laminates obtained. In addition, the resin permeability coefficient for each laminate and the AF for tensile and flexural module depending on fiber direction were calculated during production. Many actual test data were obtained versus response to seven factors and five variables. Instead of the experimental designs recommended in response surface methodology (RSM), 64 actual test data were used as responses of the model. In the optimization with the Minitab, the minimum mechanical AF was desired in return to maximum UTS, UFS, and permeability coefficient. Optimum stacking sequence, PLY, DEG, permeability coefficient, and AFs were determined through using RSM. Consequently, the most optimal composite laminate was suggested in real terms in the desirability rate of laminate D=0.6731 with the stacking sequence of [822252]6, six plies, and 0 °/90 ° fiber direction.

Experimental Characterization of a Large-Range Parallel Kinematic XYZ Flexure Mechanism

Abstract Previously, we reported the conceptual design of a novel parallel-kinematic flexure mechanism that provides large and decoupled motions in the X, Y, and Z directions, along with good actuator isolation, and small parasitic error motions (Awtar, S., Ustick, J., and Sen, S., 2012, “An XYZ Parallel-Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom,” ASME J. Mech. Rob., 5(1), p. 015001). This paper presents the detailed design and fabrication of a high-precision experimental setup to characterize and validate the motion attributes of this proposed flexure design via comprehensive measurements. The unique aspects of this experimental setup include a novel modular construction and exact-constraint assembly of the flexure mechanism from 12 identical parallelogram flexure modules. The flexure mechanism along with the sensing and actuation setup in the experiment is designed to enable large range (10 mm) in each direction. Experimental measurements and finite-elements analysis demonstrate &amp;lt;3% variation in motion direction stiffness, 20.4% lost motion, &amp;lt;11.6% cross-axis error, &amp;lt;3.3% actuator isolation, and &amp;lt;9.5 mrad motion stage rotation over the entire 10 mm × 10 mm × 10 mm range of motion.

Synthesis and characterization of natural fiber reinforced laminated thermoplastic composite

As increase in the use of eco-friendly, natural fibers are used for the reinforcement of polymer composites which has the light weight and low-cost polymer composites with better mechanical properties which offers exceptional properties over glass fiber. In this work, Basalt fiber reinforced Polypropylene (PP) laminated composite was manufactured by the compression moulding process. The variations of impact, flexural and compression strength and modules of the composite according to the number of basalt fiber layers were investigated. Scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX) conducted on the surface of the composite reveal the superior interfacial linkage between the basalt fiber and PP matrix. Hence, this offers a comprehensive discussion on synthesis and characterization of basalt fiber with polypropylene reinforced laminated thermoplastic composite.

Design and Evaluation of Compliant Modular XY Positioning Stage

ABSTRACT In precision engineering applications, compliant micropositioning stages with properties of long travel range, high accuracy and compact size are desirable. The majority of the existing research efforts are focused on monolithic compliant positioning stages with above merits. However, the monolithic stages possess a major drawback that failed components cannot be replaced and it requires time-costly machining process, i.e. wire electric discharge machining. To overcome these drawbacks, the stage using the concept of modular design with parallelogram flexure module is proposed. In the modular design, failed components can be easily replaced. The stage is driven by large range voice coil actuators (VCA). The static and dynamic analytical models based on stiffness matrix method are adopted for evaluating the performances of the stage. The accuracy of analytical models is validated by FEA results. Finally, experimental test is carried out to evaluate the performance. The stage provides translational motion of ± 5 mm along working direction and limited cross axes coupling of 10m in other direction for nonlinear behaviour. The proposed stage has resonant frequency of 15 Hz. The results obtained validate similar static and dynamic performances and trajectory tracking capabilities of the modular micro-positioning stage as that of monolithic stage.

Investigation of Thermal Properties of Waste Tungsten Carbide (WC) loaded HDPE Matrix

In this study, the thermal properties of HDPE polymer composite materials with waste tungsten carbide (WC) powder has been investigated. This waste used as additive material is produced by the accumulation of particles of tungsten carbide used as cutting tool in the machining industry. In machining sector, a significant amount of cutting tool wastes are generated and re-use of these wastes is considered. This study covers the effects of tungsten carbide particles on the thermal properties of HDPE polymer matrix. This waste filler material up to 50 wt% were used in the matrix. Mechanical properties of composites such as tensile and flexural strengths additionally elastic and flexural modules were investigated. The crystallinity percentage, phase change temperatures and specific heat capacities of WC filled HDPE composites were performed by DSC. Viscoelastic properties such as storage modulus, loss modulus and damping factor of the composites as a function of temperature were evaluated by DMA. In addition, thermal conductivity of the composites were investigated.

Адитивне формування вуглекомпозитів на основі L-полілактиду

Study of the FFF additive manufacturing process of composite material based on L – polylactide (PLLA) with ultra-short carbon fibers. Tensile strength and elongation at break for all test specimens were determined according to ISO 527. Tensile modulus - ASTM D638-10, specimen density - PN-EN ISO 1183, microscopic examination - according to ASTM E2015 - 04 (2014). Charpy Shock Tests ISO 179 and ASTM D256. Bending test method ISO 178 and ASTM D 790. The rational modes of FFF additive manufacturing (AM) of carbon fiber composite based on PLLA was established. Properties of carbon fiber PLLA and unfilled PLLA was determinated for AM formed samples and injection molded samples. Carbon fiber composites have significantly higher flexural and tensile module us values compared to the original L-polylactide, which is due to the effect of polymer matrix reinforcement by the fibrous component. However, finished products obtained by AM PLLA carbon composite have a lower impact strength and tensile strength, which is likely to be due to the fact that the carbon fibers are short (50-60 mkm) and have a cavitations effect during injection molding and AM. Density of carbon fiber filled PLLLA was lower the theoretically calculated value for filament material as well for injection molded and AM formed samples. Density reduction probably the main cause of impact properties deterioration due to cavity forming around carbon fibers. Density and tensile properties of AM formed samples can be changed by AM slicing parameter – extrusion multiplier. Cavitation effect for carbon fiber composites observed for PLLA composite in form AM filament, injection molded parts and AM formed samples. Cavity forming was confirmed by optical microscopy and density measurement. Possible reason for cavity forming is orientation deformation of the fiber in polymer matrix during the formation of the filament. The effect of cavitation also persists in the AM of products from carbon composites due to the passage of the orientation at the exit of the printer nozzle. The possibility of regulating the density and physical and mechanical properties of carbon composite products obtained by the additive manufacturing method has been established. Selection of rational values of the extrusion multiplier and the direction of the layers in the additive molding allows you to create products with the desired complex of properties.

Effect of MMT Clay on Mechanical, Thermal and Barrier Properties of Treated Aloevera Fiber/ PLA-Hybrid Biocomposites

In this research, the PLA- biocomposite and PLA- hybrid biocomposites were prepared with twin screw extruder, two-roll mill, and compression molding method. The PLA based bio-composites are fabricated with 30% of treated aloevera fiber and 0, 1, 2 and 3 wt% nanoclay filler. The influence of MMT clay on thermal, mechanical and barrier properties of PLA-biocomposite and PLA-hybrid biocomposites has been studied. The PLA-hybrid biocomposites thermal, mechanical and water resistance properties are increased with adding of MMT clay. However, 1 wt.% MMT included PLA-hybrid biocomposites exhibits increased tensile, flexural, impact and abrasion resistance properties than PLA- biocomposite, the improvements 5.72, 6.08, 10.43, and 45.71% respectively are observed. The PLA-bio and hybrid biocomposites showed higher tensile modules 25.76, 18.84, 31.53 and 32.30% respectively, and flexural modules 61.42, 60.95, 66.66 and 79.04% respectively, than pure- PLA. The results TGA analysis depicted that inclusion of MMT clay can improve the decomposition temperature of the PLA-biocomposites. The addition of 3 wt.% MMT clay can improve the PLA- biocomposite decomposition temperature from 295 to 299o C in T 10% likewise 338 to 350o C in T 75%. SEM analysis discloses that, MMT clay not only improves micro-structure and also it acts as a load transfer mechanism. The Physical barrier properties and biodegradability results show that water resistance of biocomposites improved and biodegradability decreased due to adding of MMT clay.