Polymer Sheets Research Articles

Effects of seawater on durability of hybrid C/BFRP-confined seawater–sea sand concrete columns under axial compression

A carbon-fiber-reinforced polymer (CFRP) sheet is wrapped around the basalt-fiber-reinforced polymer (BFRP) to develop a hybrid carbon/basalt-fiber-reinforced polymer (C/BFRP) so as to protect the basalt fibers in touch with chloride ions. Tensile testing is conducted on the BFRP and hybrid C/BFRP sheets. The effect of the durability of the fiber-reinforced polymer sheet on the behavior of the seawater–sea sand concrete (SSC) columns confined by the BFRP and hybrid C/BFRP sheets is examined using axial compression testing. The tensile strength retention and elongation at break retention of the hybrid C/BFRP sheet improve by 41% and 24% higher than those of the BFRP sheet after 12 months in seawater. The ultimate strength of the BFRP-confined SSC column decline by 40% more than those of the hybrid C/BFRP-confined SSC column respectively, after 12 months of seawater immersion, resulting from the reduction of lateral pressure provided by the BFRP and hybrid C/BFRP sheets in seawater. A formula for calculating the long-term ultimate strength and ultimate strain of the FRP-confined SSC column is proposed, and its predictions agree well with the test results. The hybrid C/BFRP sheet proves more efficient than the BFRP sheet in confining the seawater–sea sand concrete columns.

Confinement-based direct design method for fibre reinforced polymer confined CFST short columns

The paper presents a detailed analysis of the behaviour of circular and square concrete filled steel tube (CFST) short columns strengthened externally with carbon or glass fibre reinforced polymer sheets (CFRP or GFRP, respectively). A thorough review of existing test information is presented and discussed, and the most salient parameters in terms of the overall strength are identified. There are a large number of influential and inter-related parameters which affect the load-carrying capacity, including the geometry, cross-sectional shape, type of steel, concrete strength, boundary and loading conditions, and type of FRP. It is shown that existing design approaches do not reliably predict the strength for the full range of possible parameters. Therefore, this paper proposes a new design model to calculate the axial compressive strength of FRP-confined concrete filled steel tubular (CFST) short columns with either a circular or square cross-section. The method accounts for the various complexities which affect the behaviour, yet presents a user-friendly, performance-based design expression. It is based on an evaluation of the lateral confining pressure provided by the both the FRP and the steel tube to the concrete core. This is employed in the confinement-based direct resistance calculations. The paper validates the approach by comparing its capacity predictions with a large database of experimental results and alternative design models available in the literature. The results show that the proposed model provides much accurate strength predictions with greater reliability for the full range of parameters examined, than existing methods.

Modeling and Solution of an Unsteady Flow of a Third Grade Fluid Over an Infinite Parallel Rigid Plate Within a Porous Medium

It is known by many researchers that non-Newtonian fluids are regarded as important and appropriate in technological techniques and several industrial manufacturing processes such as in polymer sheet extrusion from dye, drilling of oil and gas well to mention a few. Due to such reason a model of such type of fluid called the differential type model in which the third grade fluid is categorized. The skin friction, Nusselt number, and Sherwood number through the graphs obtained, were also obtained. The nonlinear partial differential equations were solved using He – Laplace method. He – laplace method is a combination of Homotopy perturbation method with the Laplace transform method which is used in determining linear together with the nonlinear partial differential equations, and the use of He’s polynomials for the nonlinear term. Amongst many results obtained; the velocity, temperature and concentration profiles diminish due to the increase in suction parameter. Higher values of magnetic parameter decreases the fluid velocity. The temperature distribution is enhanced by the increment in radiation parameter. Upsurging values of chemical reaction decline the concentration of the fluid.

Reprocessable Vanillin‐Based Schiff Base Vitrimers: Tuning Mechanical and Thermomechanical Properties by Network Design

AbstractBio‐based polymer building blocks derived from abundant biomass represent a promising class of monomers for the synthesis of sustainable high‐performance polymers. Lignin‐derived vanillin is used as a bio‐based, aromatic molecular platform for chemical modifications. The use of vanillin aldehyde derivatives as monomers with different alkyl chain length, cured with bio‐based and less‐toxic di‐ and triamines, leads to covalent adaptable Schiff base networks and thus enables sustainable and thermally reprocessable high‐performance materials without using highly toxic amines. A process is presented to prepare homogeneous films of crosslinked materials that are thermally reprocessable while maintaining their mechanical performance. The network structures, mechanical properties, and thermal stability of the obtained polymeric sheets are characterized in detail. By systematically adjusting the composition of the network building blocks, the mechanical properties could be varied from tough materials with a high elastic modulus of 1.6 GPa to materials with high flexibility and elastomeric behavior with an elongation at break of 400%. Furthermore, the stress–relaxation behavior of stoichiometric and nonstoichiometric Schiff base vitrimers is investigated. The combination of bio‐based building blocks and the degradability of Schiff base networks under acidic conditions resulted in sustainable, environmentally friendly, chemically and thermomechanically recyclable vitrimers with self‐healing and shape‐memory properties.

Investigation on bonding behavior of basalt fiber reinforced polymer (BFRP) sheet reinforced concrete beam

Although basalt fiber reinforced polymer (BFRP) sheet offers promising benefits including environmental friendliness and excellent mechanical performance in concrete reinforcement, its full potential is still hindered by the lack of understanding about their bonding mechanism. Therefore, the comprehensive investigation of the bonding behavior of BFRP sheet reinforced concrete is necessary. This work aims to address the research gap between the analytical design and industrial application of BFRP sheet reinforced concrete due to the complicated bonding behavior. Analytical method, experimental measurement, and numerical simulation are employed to comprehensively investigate the bonding behavior of BFRP sheet reinforced concrete. According to the mechanical model and assumptions of the reinforcement, analytical solutions for interfacial stress and strain are derived. In addition, four-point bending test are conducted on specimens, and multi-view digital image correlation (DIC) technique is used to analyze the deformation on concrete part and BFRP sheet simultaneously. Based on analytical and experimental results, finite element model (FEM) is applied to simulate mechanical behavior of BFRP sheet reinforced concrete beam, and parametric analysis is further conducted. Results reveals that the maximum interfacial stress appears at the end of bonding region so that BFRP debonding at the end is the main failure mode. The strain distribution of BFRP sheet obtained by multi-view DIC indicates that there is an effective bonding region. Besides, strain can be used as a variable to validate numerical model by analytical and experimental results. The validated numerical simulation could be conducted for the internal response study and application design of BFRP sheet reinforcement.

Ductility of RC Columns confined with FRP Sheets

AbstractMany existing structures show insufficient seismic capacity, with the lack of members' ductility being a critical factor. Aim is to manage to increase their ductility, through confinement with composite fiber reinforced polymer (FRP) sheets. In the present paper, available analytical procedures of Eurocode 8‐Part 3 (2005) and draft of 2022 and the Greek Code for Structural Interventions (CSI) of 2013 and the revision of 2022 are examined, compared together with an analytical model proposed in the literature. Analytical results of the above procedures are also compared both with available experimental data and with each other and the degree of their reliability is evaluated. The current EC8‐3 (2005), although in many cases converges quite well with the experimental data, unrealistic results are obtained for a large thickness of the confined material. This seems to be corrected in the proposed EC83 revision of 2022. The Greek CSI 2013 adopts a very simple straight‐forward analytical procedure producing the most conservative results, while the revised analytical expressions included in the 2022 version, has a better convergence with the experiments. However, for large thickness of confinement material, the ductility factor values are unrealistically high. The model proposed in the literature has the advantage of correcting the aforementioned unrealistic result.

Experimental Study on the Static Behavior and Recovery Properties of CFRP/SMA Composites

Strengthening reinforced concrete elements with externally bonded prestressed fiber reinforced polymer (FRP) sheets has become a popular reinforcement technology in recent years. However, in practical engineering applications, due to the limitations of construction operation space and the need for specialized design of tensioning and anchoring devices, it is very cumbersome to apply prestressing force to FRP sheets. Therefore, using the recovery effect of shape memory alloys (SMA) to introduce prestressing into FRP sheets can innovate a new approach by combining FRP sheets and SMA wires. In order to study the basic mechanical properties of FRP/SMA composites, carbon fiber reinforced polymer and shape memory alloys were used to make the composite specimens, and uniaxial tensile tests were carried out on them. The mechanical properties such as the stress-strain curve, failure mode, ultimate tensile strength and fracture strain were obtained. The test results show that CFRP sheet exhibits obvious linear elastic behavior in tensile tests. The stress-strain curve of SMA wire can be divided into four stages: the linear elastic stage, yield stage, strengthening stage and failure stage. The fracture strain at failure can reach 7%, which indicates excellent deformation properties. The loading and unloading cycles have little effect on the mechanical properties of SMA wire. With the increase in the loading rate, the ‘stress plateau’ section of the phase transformation section of the SMA wire hysteresis curve gradually transits to an oblique upward curve. Increasing the pre-strain value within a certain range can improve the resilience of SMA wires. SMA wires with a pre-strain value of 8% can provide a maximum resilience of 514 MPa after heating to the austenitic state. A prediction model for the number of temperature cycles and maximum recovery force of SMA was proposed and validated. According to this model, the SMA wires can still provide stable resilience after 30 cycles. Increasing the amount of wire (volume ratio) can improve the maximum fracture strain and ultimate tensile strength of CFRP/SMA composite specimens, and the more wire is added, the greater the residual strength after fracture. The diameter of the fiber can significantly reduce the maximum fracture strain and ultimate tensile strength of the FRP/SMA composite specimen.

Experimental and Analytical Study on the Axial Behavior of Circular High-Strength Concrete Columns with Hybrid Carbon Fibers and Steel Confinement System

This paper describes a work that examines a new solution to the problem that arises from the relatively high amount of transverse reinforcement required in HSC columns. It presents an alternative to common transverse steel reinforcement, a dual system comprising steel ties and a carbon-fiber mesh (CFM) applied internally together with steel ties. The behavior of the proposed system was examined in this work in a series of twelve laboratory tests of circular stub column specimens. The experiments performed in this work focused on the columns’ load and displacement capacities. The tests were planned with the aid of an analytical model that was originally developed for a hybrid system of external fiber-reinforced polymer (FRP) sheets and internal steel, and was adapted for the current system. An analysis of the results shows that for a given amount of conventional transverse steel, the application of the carbon-fiber meshes adds efficiency to the rebar confinement system, in terms of both the load bearing capacity and the ductility, and for specimens with the hybrid confinement system, the higher the carbon fiber amount the larger the ductility improvement. Furthermore, fair to good agreement was observed between the model and the measured stress–strain curves, especially those of the peak stresses. Based on the above findings and the added benefit of fire resistance, the hybrid method appears to be promising for confining HSC columns.

Low-energy α-particle irradiation of polymeric-based nanofiller

In this study, the induced defects and modifications enhanced by alpha particle on CdO and ZnSe-doped polymethyl methacrylate (PMMA) were investigated. Casting method was used to prepare three sets of thin polymeric sheets doped with variable concentrations of the selected fillers. The prepared CdO and ZnSe particles were in the range 3–21 nm. The samples were irradiated with 4.5 MeV α-particle emitted from 241Am radioactive source at gradually increased fluence. The enhanced change that occurred in the physical properties for both types of samples due to α-particle irradiation was measured using Fourier transform infrared (FTIR), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), photoluminescence (PL) spectroscopy. All the pristine samples exhibited two separated direct band gaps around 4.0 eV and 4.6 eV, while the irradiated samples showed decreasing for the first band gap up to 3.71 and the second gap remained almost unchanged. The three investigated sets displayed PL emission peaks within the range 270–700 nm. The intensity of the PL peaks was increased by increasing the filler concentration. The net PL was quantified using the area under the emission peaks which showed that α-particle causes interchangeable defects and cross-linking processes. The formation of C–H and O–H function groups due to α-particle interactions was confirmed by FTIR analysis. The results revealed that the filler–polymer interface has a great impact on the formed defects which control the observed characteristics in the polymeric composite medium. The presented data are very helpful for α-particle dosimetric applications using these types of polymeric composites.

Experimental and simulated etched track profiles for two relativistic ions treated under different etching conditions: How to shape different track envelopes

PADC polymer sheets of thickness 650 μm were exposed to normal incident high energy ions of 7 GeV Si and 17.48 GeV Ni with particle density ≈ 103 particles/cm2. Chemical etching was carried out under soft and strong etching conditions, and parameters of track diameter and cone length variation with depths were measured and recorded at successive times during the etching process, including snapshots of the etched track profiles. A computer program using a sophisticated chemical etching model including a variation of the bulk etching rate of the detector material was used. This program uses experimental data of a variable bulk etch rate with depth (Vb (z)) and an average longitudinal (Vt) etching rate, for each etching condition and ion. A good agreement is obtained between simulation and experiment in all cases, which validates the choice of the model used and the constant Vt approximation. It is shown that the same latent track due to a given ion gives different three-dimensional shapes depending on the chemical etching conditions used. The production of etched tracks with funnel shapes is one of the originalities of this work. The simulation tool developed allows for exploring the production of microcavities with specific shapes using polymer sheets exposed to high-energy ions.

Numerical analysis for tangent-hyperbolic micropolar nanofluid flow over an extending layer through a permeable medium

The principal purpose of the current investigation is to indicate the behavior of the tangent-hyperbolic micropolar nanofluid border sheet across an extending layer through a permeable medium. The model is influenced by a normal uniform magnetic field. Temperature and nanoparticle mass transmission is considered. Ohmic dissipation, heat resource, thermal radiation, and chemical impacts are also included. The results of the current work have applicable importance regarding boundary layers and stretching sheet issues like rotating metals, rubber sheets, glass fibers, and extruding polymer sheets. The innovation of the current work arises from merging the tangent-hyperbolic and micropolar fluids with nanoparticle dispersal which adds a new trend to those applications. Applying appropriate similarity transformations, the fundamental partial differential equations concerning speed, microrotation, heat, and nanoparticle concentration distributions are converted into ordinary differential equations, depending on several non-dimensional physical parameters. The fundamental equations are analyzed by using the Rung-Kutta with the Shooting technique, where the findings are represented in graphic and tabular forms. It is noticed that heat transmission improves through most parameters that appear in this work, except for the Prandtl number and the stretching parameter which play opposite dual roles in tin heat diffusion. Such an outcome can be useful in many applications that require simultaneous improvement of heat within the flow. A comparison of some values of friction with previous scientific studies is developed to validate the current mathematical model.

Efficiency of rapid repairing for composites and structural fibre-reinforced plastic waste aggregate concrete members

In underdeveloped countries, improperly disposed of electronic waste material (E-waste) causes environmental deterioration and health hazards. The previous related work focused on the axial performance of concrete compressive members reinforced with glass fibre reinforced polymer (GFRP), rather than the efficacy of repairing them after minor damage. The present work has endeavored to deliberate the structural performance of partially damaged E-waste aggregate concrete (EAC) compressive members reinforced with structural synthetic fibres reinforced with GFRP bars and GFRP spirals. Carbon fibre-reinforced polymer (CFRP) sheets were utilized to quickly restore the damaged samples. Twelve circular samples with diameters of 250 mm and heights of 1000 mm were constructed. Six samples were reinforced with GFRP bars and spirals (SSEAC compressive members) while the others had steel reinforcement. Following concentric and eccentric compression, which caused a 30% reduction in axial load-carrying capacity in the stage following peak loading, the samples were repaired using CFRP sheets. Before and after their rapid repair, samples' axial load-carrying capacity, load-shortening response, stiffness index, axial shortening, strength index, ductility index, and failure modes were assessed. These factors included spiral pitch, CFRP wrapping, structural synthetic fibres, E-waste concrete, and reinforcement type. The findings showed that as compared to the original compressive members, both restored SSEAC and GSEAC compressive members had good structural behavior in terms of studied parameters due to the efficiency of CFRP wraps. A new theoretical model is also suggested to predict the axial load-carrying capacity of CFRP-repaired members.

Thermofluid of Maxwellian type past a porous stretching cylinder with heat generation and chemical reaction

This article evaluated the effects of heat generation and the chemical reaction of Maxwell fluid over a porous stretching cylinder. Partial differential equations are framed using the mentioned parameters. The partial differential equations for momentum, heat, and mass are changed using similarity transformations into highly nonlinear ordinary differential equations. These equations are answered numerically via the Runge-Kutta with the shotting scheme of the 4th order in MATLAB with the help of inbuilt software bvp4c. Results are offered graphically and in tabular format for essential parameters over a velocity, temperature, concentration, skin friction coefficient, Sherwood number, and Nusselt number. We checked our coding against an existing article and obtained a good match. The essential findings of this research are that velocity decreases as the permeability parameter rises. It has been observed that a viscoelastic fluid parameter induces a decreasing velocity profile. Due to the Maxwell fluid, porosity, heat generation, and chemical reaction parameters, the thermal profile has been improved. These results have several manufacturing applications, including metal turning, the fabrication of glass filaments, the formation of elastic sheets, wire drawing, the ejection of polymer sheets by oil companies, and the synthesis of polymers.

Couple effect of joule heating and multiple slips on an unsteady electromagnetic nanofluid towards a stagnation point: A statistical inspection

This research is focused on the examination of an unsteady flow of an electromagnetic nanofluid close to a stagnation point over an expanded sheet kept horizontally. Buongiorno’s nanofluid model is revised with the combined influence of the externally applied electric and magnetic fluxes. Moreover, the underneath surface offers multiple slips into the nanofluid flow. The leading partial differential equations (PDE) are renovated to the nonlinear ordinary differential equations (ODE) with the assistance of similarity transformations. Thus, the outcomes are received numerically by using the RK-6 with Nachtsheim–Swigert shooting technique. The enlistment of the outcomes for the momentum, energy and concentration profiles along with the skin-friction coefficient [Formula: see text], Nusselt number [Formula: see text] and Sherwood number [Formula: see text] for several parametric values are presented in a graphical and tabular form and discussed in detail. The variation of streamlines with respect to the unsteadiness parameter is also recorded. Statistical inspection reveals that the flow parameters are highly correlated with the wall shear stress, wall heat and mass fluxes. Findings indicate that the escalation of electric flux tries to intensify the hydrodynamic boundary layer meanwhile the magnetic flux assists to stabilize the growth by reducing it for both the steady and unsteady flow patterns. Influence of velocity slip parameter [Formula: see text] from 0.0 to 1.5 causes the reduction in [Formula: see text] by 16.98% for steady flow while 60.27% for time-dependent flow case. Moreover, we expect that these theoretical findings are very much helpful for several engineering and industrial applications such as polymer sheet productions, manufacturing automobile machines, cooling microelectronic chips, etc.

Torsional behavior of FRP-strengthened reinforced concrete members considering various wrapping configurations: Theoretical analysis and modeling

Reinforced concrete (RC) structural members such as spandrel, flanged and curved beams, slab beams, and bridge girders may be subjected to significant torsional loading. Despite extensive research on the strengthening of RC members, very little is known about the torsional behavior of RC members strengthened with fiber-reinforced polymer (FRP) sheets. Therefore, very limited guidelines apply to the design of externally bonded FRP systems for torsional strengthening, and no design provisions exist for the U-wrapped and 2-sided strengthening systems in torsion. This study aims to contribute to this growing area of research by developing a new analytical model to predict the full torsional response of strengthened RC members with many conventional configurations such as spiral, transverse and longitudinal FRP, continuous and intermittent strips along the beam length, side bonded, and full-wrapped systems. Moreover, this study provided an analytical model accurately predicting the contribution, efficiency, and failure mode of side-bonded strengthening systems. Additionally, the influence of various parameters such as FRP stiffness and transverse steel reinforcement ratio is taken into account in the constitutive law of concrete and internal reinforcement for the first time. The good agreement between the test results of 32 collected FRP-strengthened RC beams from the literature and the theoretical ones, which were predicted through programming proves the validity and accuracy of the presented theory.

A metal-free catalyst based on g-C3N4 functionalized with cyamelurate-like groups: Catalytic properties and mechanism of a new heterogeneous Fenton-like catalyst

We prepared fragments of polymeric g-C3N4 sheets functionalized with cyamelurate-like functional groups, evaluated their Fenton-like catalytic properties and proposed a reaction mechanism for the formation of hydroxyl radicals on the surface of the materials in presence of H2O2. The controlled fragmentation/functionalization of g-C3N4 was characterized by a variety of techniques including SEM, TEM, FTIR and potentiometric titration. The performance of the catalysts proved to be dependent on both the cyamelurate-like functional groups and the conjugated structure of the polymeric g-C3N4 sheets, with the kinetics of the catalyzed reaction being faster at higher pH. In addition, in the absence of the contaminant, no significant consumption of hydrogen peroxide was observed. The reaction mechanism of oxidizing radicals formation was elucidated using cyclic voltammetry and EPR spectroscopy in parallel with theoretical calculations based on the estimate of the reaction Gibbs free energy of HO• and HOO• radicals formation, generated through the reaction of surface functional groups and hydrogen peroxide. In a broader context, the results showed may contribute to the development of strategies for studying and elucidating the reaction mechanisms involving metal-free catalysts, one of the main challenges in the area and, enabling the surface designing of metal-free catalysts for different oxidation reactions.

Synthesis, crystal structures, photophysical and antibacterial properties of Ag(I) and Zn(II) coordination polymers based on a flexible bisacylhydrazone ligand

A flexible bisacylhydrazone ligand (H4L) was designed and synthesized from the condensation reaction of dialdehyde 3,3′-thiobis(methyiene)-bis-(5-methyl-salicylaldehyde) (b) with isonicotinic hydrazide. In the DMSO/methanol solution, two coordination polymers (CPs), formulated as {[Ag(H4L)NO3]·DMSO·2H2O}n (CP 1) and {[Zn2(H2L2-)2]·3DMSO·3H2O}n (CP 2), were synthesized from H4L with Ag(I) or Zn(II) ions, respectively. These two CPs were characterized via elemental analysis, FT-IR spectra, and single crystal X-ray determination. The results show that CP 1 exists as a 1D looped-chain polymer, while CP 2 exists as a 2D sheet polymer. The coordination configurations of the two CPs were analyzed and compared in detail, which disclose the terminal pyridyl nitrogen atoms exhibit obviously stronger coordination ability compared to other sites. In addition, photophysical, electrochemical and antibacterial properties of H4L and the two CPs were investigated.

Fatigue performance of cracked diaphragm cutouts in steel bridge reinforced employing CFRP/SMA

Under long-term service conditions, fatigue cracking occurs at the diaphragm arc-shape cutouts in the orthotropic steel deck (OSD) bridges subjected to vehicle-induced vibration and cyclical wheel load. To repair cracks of the diaphragm cutouts, this study proposes two repair methods of the carbon fiber reinforced polymer (CFRP) sheets and shape memory alloys (SMA)/CFRP composite patches on the basis of crack-stop holes. The crack-stop hole eliminates the obvious source of fatigue propagation at the crack tip, but it weakens the section and harms the entirety of the diaphragm. The edge of the crack-stop hole in the cracked section becomes a new stress concentration site and the potential crack initiation point. The CFRP sheets can effectively improve the stiffness and reduce the stress amplitude of the cracked part. Moreover, the SMA/CFRP composite patches can further introduce precompression by activating SMA to reduce the stress level. Relative to the reinforcement by the crack-stop hole only, the fatigue notch factor is reduced by 12.28% and 30.76% after bonding CFRP sheets and SMA/CFRP composite patches, respectively. The fatigue tests show that the bonding of CFRP sheets and SMA/CFRP composite patches can effectively postpone the initiation of fatigue cracks and inhibit crack propagation, so they are ideal repair methods for strengthening fatigue cracks of the diaphragm cutouts in the OSD bridges.

Post Fire Behavior of Structural Reinforced Concrete Member (Slab) Repairing with Various Materials

One of the most significant building materials used to build a variety of infrastructure, military, and civil structures is concrete. It can effectively withstand fire mishaps for a long period of time. This study employs a finite element simulation approach in Three steps: the first involves applying mechanical loading, the second involves applying mechanical and thermal loading; and the third involves strengthening the damaged model. Two different strengthening procedures were used to evaluate the performance of the fire-damaged slab. Two types of strengthening techniques—carbon-fiber-reinforced polymer (CFRP) sheet and slurry-infiltrated fibrous concrete (SIFCON) jacketing—were used. Studying the performance of SIFCON and CFRP together and in two different thicknesses of each for repairing both normal and high-strength concretes after fire exposure is considered limited. An investigation of their behavior can provide insights into how effective the restoration of strength is. The study aims to assess how well various repair materials perform in restoring the durability and strength of reinforced concrete members after being exposed to fire. This will assist in determining the best materials for concrete repair after a fire. Results show that the enhancements by SIFCON with a thickness of 30 mm significantly improved many indices, including load displacement behavior, ductility, and absorption energy of the slab. Doi: 10.28991/CEJ-2023-09-08-013 Full Text: PDF

Layer-to-Layer Norm-Optimal control of Incremental sheet forming with a Data-Driven model

Incremental Sheet Forming (ISF) is a free form process for the manufacturing of sheet metal or polymer parts. In ISF, a tool is used to deform the sheet using a customized toolpath. ISF is ideal for low batch size applications, as it does not require geometry specific tooling. However, due to the lack of workpiece support throughout the forming process, ISF typically results in high geometric error when compared to other sheet forming processes such as deep drawing. Thus, in this work, a method to improve the accuracy of ISF by applying feedback control during the forming process is presented. Specifically, a norm-optimal control scheme was used to optimize the toolpath on each layer using a data-driven model which is created using a trial part. The results showed that the control algorithm implemented in this work was able to effectively improve geometric accuracy and resulted in a 50% reduction in the Mean Absolute Error when compared to the open loop. However, the controller was found to have large errors near the step-in region of each layer which were the result of model inaccuracies.