Cylindrical Mandrel Research Articles

Modeling and Programming of a Spiral Winding Cycle Using a Robotic Arm

This article is devoted to solving the problem of manufacturing products from carbon fiber composite materials, which are obtained as a result of layer-by-layer laying of carbon fiber with impregnation of their binder components. This paper presents a description of the process of spiral winding of products on a cylindrical mandrel and the mathematical model, which takes into account the coefficient of friction and the necessary reverse zones in which the tape will not slip. The model is implemented as a Python program and is capable of simulating and visualizing the step-by-step winding of a carbon tape on a cylindrical surface. It is possible to optimize the friction coefficient to ensure the tightest winding of subsequent passes. The program takes into account reverse zones, which are calculated taking into account the friction coefficient of the cylindrical mandrel. Based on the simulated winding process, a control program for the robotic arm is generated. The performance of the proposed model and its implementation was tested on a test bench with a robot.

Assess the Possibility to Substituting Crude Oil-based Film Formers in Automotive Epoxy Metal Primers with Coconut oil-derived Bio-based Polyurethane Film Formers

There is a potential risk that diminishing some islands in the world map within a short time period due to global warming unless people divert into new strategies to use crude oil sustainability or replace with renewable resources. Polyurethane (PU) is one of the most popular film-forming materials in the coating industry because of its better performance. A coconut oil-derived biobased polyol (BBP) was synthesized and acid value, viscosity, reaction water release, oil length, FTIR spectrum, differential scanning calorimetry and Lovibond colourimetric index were assessed during the synthesis. A series of pigmented renewable polyurethane metal primer (RPUMP) wet samples were prepared by using BBP under two categories as direct-to-metal (DTM) primers and undercoat primers (UCP) in two mixing ratios with polyisocyanate hardener as 2:1 and 4:1. All samples were comparatively tested with crude oil born commercially available epoxy metal (CAEMP) primers in Sri Lankan market for apparent viscosity, fineness of grinding, solid content, specific gravity, gloss, drying time, hardness, dry film thickness, adhesion, impact resistance, water resistance, salt spray resistance and cylindrical mandrel bending. According to the results, it was proven that RPUMP showed overall better performances with the corresponded CAEMP under the DTM category. But under the UCP category RPUMP showed better performances in apparent viscosity, drying time and water resistance but equal magnitude for pencil hardness. CAEMP showed better performances in solid content, specific gravity, dry film thickness, flexibility, impact resistance and salt spray resistance.

Research on the effect of temperature increase during flow forming without cooling on 6060 aluminum alloy

Abstract This paper presents the results of flow forming tests for the 6060 aluminum alloy in the T5 heat treatment condition. The tests were conducted on a cylindrical mandrel using two forming rollers without the use of a cooling agent. The purpose of the study was to conduct two experiments. In both experiments, the final gap between the roller and the mandrel was designed to be the same. The impact of the deformation value on the change in the mechanical properties of the material with the simultaneous impact of the number of forming passes was determined. In addition, the effect of the elimination of a coolant on the process was analyzed. The material temperature rise caused by friction between a pair of working parts: the roller—and the workpiece—were examined with a thermal imaging camera. This paper presents the results of microhardness tests and analyzes the impact of the forming parameters on the strength properties of the alloy. Because the forming process was done without cooling, the impact of the temperature prevailing during the deformation process on the change in the strength of the alloy was studied and analyzed. The deformation zone in which intensive grain deformation took place was determined.

Mechanical calculation of elastic folding of a thin-walled deployable composite boom for space applications

The paper investigates the stress–strain state of a thin-walled deployable N-shaped composite boom during elastic folding. A finite element model using ANSYS 2021 R2 software (explicit formulation) is developed, considering boundary conditions, loads, and analysis parameters. Numerical calculations are performed for various cylindrical mandrel radii, revealing a strong dependence on maximum stress on the mandrel radius. Results indicate reliable folding without damage for a mandrel radius of 20 mm or more. This study solves the complex problem of modeling elastic folding, providing essential information for engineers to achieve an optimal design.

Synthesis, Characterization of Bio-based Polyol and Assess the Effectiveness of Bio-based Polyurethane Direct-to-metal Coating System

Crude oil is neither a long-lasting energy source nor a raw material source, has a high consumption rate relative to a low regeneration rate and creates massive environmental disorders. Polyurethane is well known and is the most popular film forming material in the coating industry because of its better performance. A coconut oil-based polyol (biobased polyol) was synthesized and acid value, viscosity, reaction water release, oil length, FTIR spectrum, differential scanning calorimetry and colourimetric index were assessed during the synthesis. A series of pigmented wet paint samples were prepared by bio-based polyol and the optimum paint sample was selected among them based on drying time, pencil hardness, dry film thickness, cross hatch test and cylindrical mandrel blending. Two wet PU paint samples, representing commercially available crude oil-based polyols, were prepared to compare in the same aspects with a PU paint sample made with a bio-based polyol (BBP). According to the results, it was proven that bio-based PU paint showed equal magnitudes in film flexibility due to the cylindrical mandrel bending test, film hardness due to the pencil hardness test, substrate adhesion due to the crosshatch test and impact resistance. In some properties, bio-based PU exceeded at least one crude oil-based PU such as gloss, hard drying time and density. Meanwhile, bio-based PU systems must be improved in viscosity and water resistance to compete with artificial PU systems.

A Simplified Analytical Solution for the Computation of Machine Path in Filament Winding of Cylindrical Angle-Ply and Double-Double Structures

This paper presents a simplified computation approach for the machine path (or winding trajectory) of grid structures and tubes with a circular cross-section and angle-ply or double-double layup. The solution for the machine path is given through controllable degrees of freedom of a low-cost two-axis filament winding machine (FWM): mandrel rotation and translation of the delivery eye along the axis of the mandrel. The efficiency of the analytical solution for the machine path of the FWM was ascertained by automated laying the cotton thread over the geodesic and non-geodesic groove imprinted on the surface of a cylindrical polylactide mandrel. These results validated the possibility of manufacturing cylindrical composite structures with an angle-ply layup or double-double stacking sequence, without the need for expensive software, making the winding technology accessible to society and promoting university extension.

Circumferential pure shear test of thin-walled aluminum alloy tubes

In order to obtain the pure shear deformation characteristics along the circumferential direction of tubes, a circumferential shear test for thin-walled tubes is proposed in this paper. The experimental device consists of a tubular sample and two cylindrical mandrels with shear plates. The torque along the circumferential direction was applied to the tubular sample by the two shear plates to make the pre-set shearing zone of the sample under a circumferential pure shear stress state. The two cylindrical mandrels support the inner wall of the tube to avoid buckling so that the pure shear stress state can be maintained during the whole deformation process. A 5052 aluminum alloy tube with an outer diameter of 50 mm and a wall thickness of 1.2 mm was used in the test. It is shown through simulation and experiment that shear deformation is concentrated in the pre-set shearing zone. This test can be used to obtain the circumferential pure shear stress-strain relationship.

Near-field electrospinning of polydioxanone small diameter vascular graft scaffolds

The ideal “off the shelf” tissue engineering, small-diameter (SD) vascular graft hinges on designing a scaffold to act as a template that facilitates transmural ingrowth of capillaries to regenerate an endothelized neointimal surface. Towards this goal, we explored two types of near-field electrospun (NFES) polydioxanone (PDO) architectures, as SD vascular graft scaffolds. The first architecture type consisted of a 200 × 200 μm and 500 × 500 μm grid geometry with random fiber infill, while the second architecture consisted of aligned fibers written in a 45°/45° and 20°/70° offset from the long axis written, both on a 4 mm diameter cylindrical mandrel. These vascular graft scaffolds were evaluated for their effective pore size, mechanical properties, and platelet-material interactions compared to traditionally electrospun (TES) scaffolds and Gore-Tex® vascular grafts. It was found that effective pore size, given by 9.9 and 97 μm microsphere filtration through the scaffold wall for NFES scaffolds, was significantly more permeable compared to TES scaffolds and Gore-Tex® vascular grafts. Furthermore, ultimate tensile strength, percent elongation, suture retention, burst pressure, and Young's modulus were all tailorable compared to TES scaffold characterization. Lastly, platelet adhesion was attenuated on NFES scaffolds compared to TES scaffold which approximates the low level of platelet adhesion measured on Gore-Tex®, with all samples showing minimal platelet activation given by P-selectin surface expression. Together, these results suggest a highly tailorable process for the creation of the next generation of small-diameter vascular grafts.

A Low-Cost Filament Winding Technology for University Laboratories and Startups.

This paper systematically explains the methodology and results of empirical work on the development of a low-cost filament winding technology for manufacturing axisymmetric polymer composite structures with a high length-to-diameter ratio, such as tubes, motor casings, and pressure vessels. The principal objective was to examine the experiences and most optimal practices in the development of computer-controlled equipment and auxiliary tooling for the wet filament-winding process. To preclude expensive commercial software for the automated control of a winding machine, analytical equations were derived for the winding trajectory of a four-axis filament-winding machine. The feasibility of the proposed equations was successfully validated by laying the fiber along the geodesic path marked on the surface of a cylindrical mandrel with hemispherical ends. Moreover, the carbon/epoxy cylindrical casings with hemispherical ends and port openings of the same diameter were wound to determine the thickness distribution in the hemispherical dome. The fiber volume ratio in the wound composite parts was evaluated using an optical technique.

FEM-Based Comparison of Mandrel Wear Resulting from Elongation of Pipes Manufactured from Various Materials on a Two-Roll Screw Rolling Mill

The present article discusses the cylindrical mandrel wear change during rolling using MISIS - 130 D mill depending on the type of rolled billets materials used. The research on the mandrel wear of the screw rolling mill during pipes elongation was carried out using the finite element method (FEM). The results of the wear modeling showed that the depth of the metal removed on the mandrel surface during stainless steel pipes elongation was higher as compared to alloyed and carbon steel pipes. The significant wear of the mandrel during stainless steel pipe rolling can be explained by the rise in the applied metal force resulting from the introduction of alloying components such as chromium and nickel into rolled billets materials. Consequently, the obtained modeling results can allow predicting the service life of working tools.

Technical and economic advantages of using elongating mandrel made of forged blank when rolling on a continuous mill with a controlled‑movable mandrel

In the article, the current problem of reducing the cost of pipe‑rolling products, which is especially acute in the world market of metal products high competition conditions is considered. A significant share in the cost of pipe products stands at the cost of rolling tools. Reducing the cost of buying a deforming tool allows you to make considerable savings in the seamless pipes’ production. The article presents: analysis of the economic efficiency of manufacturing long cylindrical mandrels from a semi‑finished product – forged billet at OJSC «BSW – management company of «BMC» holding»; development of the technological process for the production of long mandrels depending on the required size; the results on the manufacture of long cylindrical mandrels from forged billet at OJSC «BSW – management company of «BMC» holding», as well as their industrial tests in the conditions of the pipe rolling shop. A positive result of using long mandrels of the PQF mill made of forged blanks was obtained.

3D reconstruction of bias effects on porosity, alignment and mesoscale structure in electrospun tubular polycaprolactone

Porosity variations in tubular scaffolds are critical to reproducible, sophisticated applications of electrospun fibers in biomedicine. Established laser micrometry techniques produced ~14,000 datapoints enabling thickness and porosity plots versus both the azimuthal (Φ) and axial (Z) directions following cylindrical mandrel deposition. These 3D datasets could then be ‘unrolled’ into ‘maps’ revealing variations in thickness and porosity versus 0, −5, and −15 kV collector biases. As bias increases, thinner, more ‘focused’ depositions occur. At 0 kV bias, maximum thickness coincides with maximum porosity; at −5 kV bias, maximum thickness coincides with minimum porosity. Porosity maps show that at 0 kV, a concave-down central region of higher (~93–94%) porosity exists bounded on either side by roughly symmetric, parabolic decreases to ~87–89% which corresponds to ~15v%. At −5 kV, a different concave-up character occurs, showing a central porosity of ~82–84% bounded by symmetric, parabolic increases in porosity to ~85–86%. At −15 kV, the porosity profile shows either concave-up or linear behavior. Simultaneous decreases in net porosity versus bias (91.1%@0 kV > 83.4%@-5 kV > 80.2%@-15 kV) are sensible, but significant changes in the distribution were unexpected. Surprisingly, at 0 kV, extensive mesoscale surface roughness is evident. Optical profilometry revealed unique features ~1600 × 420 μm in size, standing ~210 μm above the surrounding surface. These shrink to only ~440 × 150 μm in size and ~30 μm higher at −5 kV bias and disappear entirely at −15 kV. Scanning electron microscopy (SEM) resolved these into novel, localized ‘domains’ containing tightly aligned fibers oriented parallel to the mandrel axis. Observation of ‘curly’ fibers in the SEMs following −5 and −15 kV indicate buckling instabilities. This agrees with prior observations of residual solvent effects: increased bias causes faster motion toward the mandrel, meaning (1) its solvent content upon arrival is higher, leading to lower viscosities less resistant to buckling/compaction, (2) higher velocities during deposition cause both decreased porosity/“denser packing” and increased buckling. Unexpectedly, we also observed substantial orientation along the mandrel axis. By modifying classical bending instability models to incorporate cylindrical electric fields, simulation revealed that horizontal components in the modified electric field alter bending loop shape, causing the observed alignment. This provides a new, easily utilized tool enabling facile, efficient tuning of orientation.

Anisogrid lattice cylinders made of thermoplastic composite under buckling loading

Anisogrid lattice cylinders have been produced by means of an innovative out-of-autoclave (OOA) process by using thermoplastic prepreg. Unidirectional thermoplastic tapes with polypropylene matrix and glass fibers were wound on cylindrical mandrels at room temperature. Composite consolidation was achieved by using the compression of a heat-shrink tube during its shape recovery in oven. A cylindrical anisogrid lattice structure was manufactured and mechanically tested under vertical loading. Results from the buckling test revealed the optimal adhesion between prepreg layers after the out-of-autoclave molding. Numerical modelling of buckling has been performed to correlate the structural behavior of the anisogrid lattice cylinder with composite material properties and geometrical features. A parametric model of the lattice structure has been defined for this aim. The proposed manufacturing technology combines the advantages of thermoplastic composites (reparability, easy handling, easy storage, long prepreg life, productivity) with the designing potential of anisogrid lattice structures in terms of lightness and stiffness.

Enhanced mandrel design for electrospinning aligned fiber mats from low volatility solvents

AbstractA cylindrical mandrel with axially aligned rods was designed and tested for the collection of electrospun fibers. Blended polyaniline/polyethylene oxide fibers were electrospun from a solution containing a nonvolatile solvent, m‐cresol. Camphorsulfonic acid served as the primary dopant and m‐cresol were used as the secondary dopant to enhance fiber conductivity. A smooth, rotating cylindrical mandrel collector failed to collect and align fibers and instead afforded a wet, sticky film. An eight‐rod, rotating cylindrical mandrel resulted in a dry, aligned fiber mat composed of 7–10 μm diameter fibers. Alignment was maintained for at least 18 h of continuous spinning and the resulting mat could be easily recovered from the mandrel. A simulation of the rotating system indicated that the efficient formation of dry, nonsticky, aligned fiber mat was facilitated by the high mass transfer coefficient associated with the use of corrugated rods. Experiments indicated that 6–10 rods were optimal avoiding sagging of the fibers at the low end and increased mas transfer resistance at the high end.

Flow analysis of conical spiral mandrel dies

Spiral dies are divided into three categories, namely: Flat Spiral Die (FSD), Cylindrical Spiral Mandrel Die (SMD), and Conical Spiral Mandrel Die (CSD). These dies are used to produce films via blown film extrusion and multilayer films via co-extrusion. The goal is to improve the flow distribution and to decrease the pressure drop which will result in uniform film thickness and reduced energy dissipation. A viscous power-law fluid model shows that low-pressure drop and proper flow distribution can be achieved in a CSD simultaneously. As the number of grooves and the initial channel depth increases, the flow distribution becomes more uniform and the pressure drop decreases. Also, there is an optimum initial clearance and clearance increment angle. The model results show that the pseudo-plastic fluid has more appropriate performance than the Newtonian and dilatant fluids in improving the flow distribution and reducing the pressure drop.

Physical characterization of electrospun polycaprolactone via laser micrometry: Porosity and condition-dependent jet instabilities

Electrospinning has acquired intense recent interest as a means of advancing filtration, tissue engineering, and catalysis. As a part of this evolution, better characterization of electrospinning conditions has been identified as a variable that can improve performance. We use a unique realization of laser micrometry to reveal previously unknown porosity trends within electrospun poly(ε-caprolactone) (PCL) deposited onto a cylindrical mandrel. Electrostatic charging of two PCL-based solutions took place in N2 at 0 and 50%RH under three collector biases (−5, 0, and +5 kV). At 0%RH, all three gave rise to porosity values of 85–95%, where 95% occurred at the edges of +5 kV; mid-point values were a relatively constant 86–90%. Increases to 50%RH at –5 kV caused edge porosity values of ~56%; mid-point values were ~91% due to a well-defined ‘texture.’ The addition of higher dielectric constant Rose Bengal (RB) caused minor porosity changes at 0%RH, but dramatic changes at 50%RH; mid-points were as low as 12%; edge values reached >80% before decreasing to ~60%. Dense fiber agglomerations were present due to RB's effect on surface charge migration and decreased fiber repulsion along with deposit relaxation likely due to increased solvent retention. Multi-needle depositions of separate PCL and PCL-RB solutions at 0%RH produced a visually uniform, ~90% porous deposition. However, RB analysis showed separated contributions containing either RB-rich or RB-poor fibers. At 50%RH, midpoint porosities decreased to 0% and similar RB-poor or RB-rich regions occurred where 0% was associated with RB likely due to jet segregation due to differences in the grounding ability of PCL versus PCL-RB solutions. This analysis captures variations in through-thickness porosity to provide unprecedented detail regarding conditional effects on electrospun products.

Design of a disk-mandrel assembly for achieving rotational autofrettage in the disk

Rotational autofrettage is a recently proposed method to induce beneficial residual stresses in axisymmetric hollow cylindrical bodies. The feasibility of the process has been studied for both disks and cylinders used in many engineering applications. The earlier analyses of rotational autofrettage of disks are based on certain assumptions. One of the crucial assumptions is the free rotation of the disk. However, the free rotation of the disk is practically difficult. In practice, it is feasible to rotate the disk by shrink-fitting it over a solid cylindrical mandrel. In view of this, a design of a disk-mandrel assembly for achieving rotational autofrettage in disks is proposed in this article. The main aim of the design is to obtain appropriate values of the disk-mandrel interference and the rotational speed of the assembly to prevent the loss of contact of the disk with the mandrel during rotation. The critical speeds corresponding to the yield onset, contact separation and the full plastic deformation of the disk are obtained as a function of shrink interference. The safe operating design parameters can be decided by plotting the critical speeds with varying interference values. A detailed stress analysis during elastic-plastic loading of the assembly followed by the analysis of residual stresses in the assembly after unloading is presented. The analysis is based on the plane stress assumption, Tresca yield criterion and elastic unloading. The analysis is validated with a finite element method model in ABAQUS. The proposed design is illustrated through the numerical example of an ASTM A723 disk-mandrel assembly to achieve rotational autofrettage in the disk. With a small overstrain level of 17.5% in the disk, a large magnitude of compressive residual stress, viz., 0.52 times the yield stress, is induced.

Mechanical and High-Frequency Electrical Study of Printed, Flexible Antenna Under Deformation

During usage, printed electronic components are often stretched, bent, folded, and/or twisted to conform to underlying structure. In this article, tests have been developed for characterizing the mechanical and high-frequency electrical behavior of inkjet-printed patch antennas on flexible polyethylene terephthalate (PET) substrates under uniaxial and biaxial bending. A patch antenna is designed to have a single resonant frequency of 5 GHz in free space. Polycarbonate cylindrical mandrels of 1.25” diameter and special sculptured surfaces have been used as uniaxial and biaxial bending fixtures, respectively. Up to 2000 bending cycles have been performed in both uniaxial and biaxial bending tests. During bending tests, $S_{11}$ (return loss) has been measured by a vector network analyzer (VNA) in both bent and flat configurations. Mechanical simulations have also been performed to determine the strain distribution in the printed elements which will lead to changes in electrical behavior. Scanning electron microscope (SEM) images have been taken to examine the physical damage in the printed structure and to correlate with the strain values obtained through mechanical simulation. High-frequency electrical simulations have also been performed to correlate with the bending experimental data. It is seen that the conductivity of the printed structure changes differently in different zones, due to various values of strain they undergo. Although the cracks are observed in the printed structures, the maximum relative shift in the measured resonant frequency is less than 1.66% in both uniaxial and biaxial bend tests.

Numerical Investigation on the Thermo-Mechanical Behavior of HTS Tapes and Experimental Testing on Their Critical Current

This work extends to second generation Rare-Earth Barium-Copper-Oxide ((Re)BCO) tapes an experimental procedure previously developed to analyze the impact of double bending at room temperature on the performance of Bismuth-Strontium-Calcium-Copper-Oxide (BSCCO) tapes. The modified procedure is applied to measure the critical current of a commercial (Re)BCO tape subjected to bending around a cylindrical mandrel first on one side, then on the other side, followed by the cooldown to cryogenic temperature. In the bending phase, mandrels of decreasing diameter are used to identify the minimum curvature leading to a significant reduction of the tape critical current. Furthermore, a novel finite element model is developed to complement the experimental results. The model simulates the double bending at room temperature, the following straightening of the sample, and its cooldown to cryogenic conditions. The coupled thermo-mechanical numerical model together with the temperature-dependent mechanical properties allow investigating the combination of thermal contraction effects and bending loads in the whole domain of the problem. The experimental and numerical results obtained help to give a better insight in the distribution of the strain and stress components inside the (Re)BCO tape and to evaluate their impact on the conductor electrical performance in relevant operating conditions.

Three-Dimensional Printing on a Rotating Cylindrical Mandrel: A Review of Additive-Lathe 3D Printing Technology

Three-dimensional (3D) printing is a powerful rapid manufacturing technology with wide applicability in scientific research, in industry, and for the home hobbyist. A popular 3D printing discipline...