Browsing by Author "Kandan, Karthikeyan"
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Item Open Access Assessing PET composite prosthetic solutions: A step towards inclusive healthcare(Elsevier, 2024-10-02) Nagarajan, Yogeshvaran R.; Farukh, Farukh; Kandan, Karthikeyan; Singh, Amit Kumar; Mukul, PoojaThe demand for affordable prostheses is particularly high in Low Middle-Income Countries (LMICs). Currently, sockets are predominantly manufactured using monolithic thermoplastic polymers, which lack durability and strength, or consumptive thermoset resin reinforcing with expensive composite fillers like carbon, glass, or Kevlar fibers. However, there exist unmet and demanding needs among amputees for procuring low-cost, high-strength, and faster socket manufacturing methods. We evaluate a socket made from a novel manufacturing technique utilizing an affordable and sustainable composite material called commingled PET (polyethylene terephthalate) yarn, along with a reusable vacuum bag, to produce custom-made sockets in a purpose-built curing oven. Our innovative fabrication methodology enables the production of complex-shaped patient sockets in under 4 h. To evaluate the efficacy and performance of the PET sockets, we conducted trials with both unilateral and bilateral amputees over a six-month period, in collaboration with Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS) in India. Utilizing a 6-min walking test, we measured various gait parameters, including ground reaction forces and flexion angle, for both unilateral and bilateral amputees. The gait analysis conducted on amputees using our PET-based sockets demonstrated their ability to engage in daily activities without interruptions, reaffirming the functional efficacy of our approach. By combining self-reinforced PET with our novel fabrication technique, we offer a unique and accessible solution that benefits clinicians and patients alike. This study represents significant progress towards achieving affordable and personalized prostheses that cater to the needs of LMICs.Item Metadata only Biomechanical Flow Amplification Arising From the Variable Deformation of the Subglottic Mucosa(Elsevier, 2017-04-19) Goodyer, E. N.; Muller, Frank; Hess, Markus; Kandan, Karthikeyan; Farukh, FarukhItem Open Access Bottle House: A case study of Transdisciplinary research for tackling global challenges(Elsevier, 2018-07-27) Whitehead, Timothy; Abuzeinab, Amal; Adefila, Arinola; Akinola, Yewande; Anafi, Fatai; Farukh, Farukh; Jegede, Oluyemi; Kandan, Karthikeyan; Kim, Boksun; Mosugu, Emmanuel; Oyinlola, M. A.Globalisation has brought a number of challenges to the fore, particularly those problems which require collaboration, innovation and capability development between nations. There are some complex issues piquing the attention of researchers with respect to sustainable development, such as, waste management, climate change, and access to amenities, housing or education. Non-Governmental Organisations, Institutions, governments and others working in the field of international development have been grappling with these difficulties for decades. However, it is becoming apparent that many of these difficulties require multifaceted solutions, particularly in Low and Middle Income countries (LMIC) where it is difficult to consolidate gains and fund schemes. Development work can sometimes be disjointed and inefficient, impairing the capability of local communities and inhibiting sustainable and innovative approaches. Transdisciplinary collaboration is reliably a more efficient way of tackling some of the most pertinacious challenges. This paper presents findings from a transdisciplinary research project focussed on developing resources and capacity for the construction of affordable homes in a low income community in Nigeria. The project explored the suitability of using upcycled materials such as plastic bottles and agricultural waste in construction. Using a user-centred, co-creation methodology, a team of experts from the UK and Nigeria worked with local entrepreneurs to build a prototype home. The study explores the functionality of the home and the sustainability of project. The findings demonstrate the benefits of tackling global challenges from a transdisciplinary perspective. This has implications for researchers focused on developing technical solutions for low-income communities.Item Open Access Compressive response of a 3D non-woven carbon- fibre composite(Elsevier, 2017-12-09) Das, S.; Kandan, Karthikeyan; Kazemahvazi, S.; Wadley, H. N. G.; Deshpande, V. S.The compressive response of a three-dimensional (3D) non-interlaced composite comprising three orthogonal sets of carbon fibre tows within an epoxy matrix is analysed. First, the compressive response is measured in three orthogonal directions and the deformation/failure modes analysed by a combination of X-ray tomography and optical microscopy. In contrast to traditional unidirectional and two-dimensional (2D) composites, stable and multiple kinks (some of which zig-zag) form in the tows that are aligned with the compression direction. This results in an overall composite compressive ductility of about 10% for compression in the low fibre volume fraction direction. While the stress for the formation of the first kink is well predicted by a usual micro-buckling analysis, the composite displays a subsequent hardening response associated with formation of multiple kinks. Finite element (FE) calculations are also reported to analyse the compressive response with the individual tows modelled as anisotropic continua via a Hill plasticity model. The FE calculations are in good agreement with the measurements including prediction of multiple kinks that reflect from the surfaces of the tows. The FE calculations demonstrate that the three-dimensionality of the microstructure constrains the kinks and this results in the stable compressive response. In fact, the hardening and peak strength of these composites is not set by the tows in direction of compression, but rather set by the out-of-plane compressive response of the tows perpendicular to the compression direction.Item Open Access Conic deformation of the subglottic mucosa and its impact on the aerodynamics of the airflow over the vocal folds(PEVOC 12, 2017-08-30) Goodyer, E. N.; Muller, F.; Hess, M.; Kandan, Karthikeyan; Farukh, FarukhObjective: This study mapped the variation in tissue elasticity of the subglottic mucosa, applied that data to provide initial models of the likely deformation of the mucosa during the myoelastic cycle, and hypothesised as to the impact on the process of phonation. Study Design: 6 donor human larynges were dissected along the sagittal plane to expose the vocal folds and subglottic mucosa. A Linear Skin Rheometer was used to apply a controlled shear force, and the resultant displacement was measured. This data provided a measure of the stress/strain characteristics of the tissue at each anatomical point. A series of measurements were taken at 2mm interval inferior of the vocal folds, and the change in elasticity determined. Results: It was found that the elasticity of the mucosa in the subglottic region increased linearly with distance from the vocal folds in all 12 samples. A simple deformation model indicated that under low pressure conditions the subglottic mucosa will deform to form a cone, which could result in a higher velocity thus amplifying the low pressure effect resulting from the Venturi principle, and could assist in maintaining laminar flow. Conclusions: This study indicated that the deformation of the subglottic mucosa could play a significant role in the delivery of a low pressure air flow over the vocal folds.Item Open Access Deep penetration of ultra-high molecular weight polyethylene composites by a sharp-tipped punch(Elsevier, 2018-06-05) Liu, B.; Kandan, Karthikeyan; Wadley, H. N. G.; Deshpande, V. S.The penetration of unidirectional (UD) and [0o/90o] cross-ply ultra-high molecular weight polyethylene fibre composites by sharp-tipped cylindrical punches has been investigated. While the measured penetration pressure for both composite types increased with decreasing punch diameter, the pressure was significantly higher for the cross-ply composites and increased with decreasing ply thickness. A combination of optical microscopy and X-ray tomography revealed that in both composites, the sharp-tipped punch penetrated without fibre fracture by the formation of mode-I cracks along the fibre directions, followed by the wedging open of the crack by the advancing punch. In the cross-ply composites, delamination between adjacent 0o and 90o plies also occurred to accommodate the incompatible deformation between plies containing orthogonal mode-I cracks. Micromechanical models for the steady-state penetration pressure were developed for both composites. To account for material anisotropy as well as the large shear strains and fibre rotations, the deformation of the composites was modelled via a pressure-dependent crystal plasticity framework. Intra and inter-ply fracture were accounted for via mode-I and delamination toughnesses respectively. These models account for the competition between deformation and fracture of the plies and accurately predict the measured steady-state penetration pressures over the wide range of punch diameters and ply thicknesses investigated here. Design maps for the penetration resistance of cross-ply composites were constructed using these models and subsequently used to infer composite designs that maximise the penetration resistance for a user prescribed value of fibre strength.Item Open Access Development of affordable hot box calorimeter to determine the U-value of inhomogeneous building material(Elsevier, 2023-07-11) Alqahtani, Saad; Muhammad Ali, Hafiz; Farukh, Farukh; Kandan, Karthikeyan; Ali, HassanIn recent years, the use of three-dimensional printing to create construction components has advanced quickly; it is possible now to simplify construction, increase speed, and lower cost while using natural resources responsibly. It also allows us to use recycled material to produce building envelopes while increasing design flexibility. However, the thermal performance of building materials must be characterized to achieve the necessary energy efficiency of the building envelopes. This study aims to develop, produce, and calibrate a hot box calorimeter at a reasonable price for thermal testing components building envelope. The heat loss through these components using a hot box can be measured in a lab to get an idea of the thermal performance of the building envelopes. In order to evaluate and analyze the thermal performance of various 3D-printed building brick samples made in the labs, this study explains the design and creation of an inexpensive hot box. The hot box can conduct a conventional thermal experiment, which involves monitoring heat flux, surface temperatures, and air temperatures. The testing process, instrumentation, test conditions, and validation of the new metering box are all covered in the article. The U-value of the brand-new lattice-based 3D printed building blocks was afterward determined using the validated new hot box. It was observed that the U-values values of 1.04 W/m2.K and 0.99 W/m2.K, respectively, for small components utilizing developed hot box and larger lattice panels using commercial equipment, with a maximum variance of 5%. It highlights the dependability of the hot box apparatus, which is also made affordable to operate by using less material for specimen preparation and less energy to maintain the temperature in the hot and cold chambers. Its small size also makes setup and thermal testing of construction materials simple.Item Open Access Effect of Cavity Vacuum Pressure Diminution on Thermal Performance of Triple Vacuum Glazing(MDPI, 2018-09-19) Memon, Saim; Farukh, Farukh; Kandan, KarthikeyanLong-term durability of the vacuum edge seal plays a significant part in retrofitting triple vacuum glazing (TVG) to existing buildings in achieving progress towards a zero-energy building (ZEB) target. Vacuum pressure decrement with respect to time between panes affects the thermal efficiency of TVG. This study reports a 3D finite element model, with validated mathematical methods and comparison, for the assessment of the influence of vacuum pressure diminution on the thermal transmittance (U value) of TVG. The centre-of-pane and total U values of TVG are calculated to be 0.28 Wm−2 K−1 and 0.94 Wm−2 K−1 at the cavity vacuum pressure of 0.001 Pa. The results suggest that a rise in cavity pressure from 0.001 Pa to 100 kPa increases the centre-of-pane and total U values from 0.28 Wm−2 K−1 and 0.94 Wm−2 K−1 to 2.4 Wm−2 K−1 and 2.58 Wm−2 K−1, respectively. The temperature descent on the surfaces of TVG between hot and cold sides increases by decreasing the cavity vacuum pressure from 50 kPa to 0.001 Pa. Nonevaporable getters will maintain the cavity vacuum pressure of 0.001 Pa for over 20 years of life span in the cavity of 10-mm wide edge-sealed triple vacuum glazing, and enable the long-term durability of TVG.Item Open Access Effect of sliding conditions on the macroscale lubricity of multilayer graphene coatings grown on nickel by CVD(Elsevier, 2018-11-17) Sun, Yong; Kandan, Karthikeyan; Shivareddy, S.; Farukh, Farukh; Bailey, RichardA multilayer graphene (MLG) coating was grown on a nickel substrate by atmospheric chemical vapor deposition (CVD). The macroscale dry sliding friction behavior of the coated specimens against a stainless steel counterface was investigated under various contact loads ranging from 1 N to 5 N and at various rotational speeds from 30 rpm to 240 rpm. After the tests, the sliding surfaces were characterized by optical and scanning electron microscopes and Raman spectroscopy. The results show that contact load and sliding speed had significant effects on the lubricity of the MLG coatings under dry sliding conditions. At relatively low contact loads (1-3 N) and sliding speeds (30-120 rpm), the MLG coating exhibited good lubricity with coefficient of friction (COF) below 0.06 and lasted a long period of sliding time for more than 3600 cycles. With increasing contact loads and speeds, the COF of the MLG coating was gradually increased and the coating suffered from sudden breakdown after limited sliding cycles, losing its lubricity. Detailed examination and analysis revealed that material transfer occurred at the early stage of the sliding process, where MLG was transferred from the coating surface to the counterface. This graphene transfer was responsible for the lubricity of the sliding pair and the sustainability of the transferred material on the counterface determined the lifetime of the lubricity regime. High contact loads and high speeds favored severe plastic deformation and mechanical damages of the substrate, which limited the lifetime of the transferred material and thus the lifetime of the lubricity regime. Sliding induced defects in the MLG both on the coating and on the counterface were confirmed by Raman spectroscopy.Item Open Access Gait Abnormality Detection in Unilateral Trans-tibial Amputee in Real Time Gait using Wearable Setup(IEEE, 2023-04-17) Rathore, Radheshyam; Singh, Amit Kumar; Chaudhary, Himandhu; Kandan, KarthikeyanThe presented study proposes a novel approach to detect gait abnormalities in unilateral trans-tibial amputees using a wearable setup. The system uses force sensitive resistors and potentiometers to collect data on the user’s gait patterns. A machine learning algorithm based on Extreme Learning Machines is utilized to classify the gait patterns as normal or abnormal. The system is evaluated on a dataset of healthy and unilateral trans-tibial amputees, and the results reveal that the ELM-based classification technique achieved high accuracy, sensitivity, specificity, and F1 score. The proposed wearable gait setup is tested by conducting a standard six-meter walk test, and the collected data is segmented into stance and swing phases. The study also compares various gait parameters of healthy and amputated subjects, and the results show significant asymmetry in the amputated subjects. The proposed setup also detects asymmetry in force distribution under each foot. The study’s findings reveal that the proposed wearable gait setup is a reliable and effective tool for gait analysis in unilateral trans-tibial amputees, and the results are comparable with those obtained using a Vicon gait measurement system.Item Open Access High strain rate compressive response of ultra-high molecular weight polyethylene fibre composites(Elsevier, 2019-04-20) Liu, B. G.; Kandan, Karthikeyan; Wadley, H. N. G.; Deshpande, V. S.The mechanisms of deformation during the dynamic in-plane compression of 〖[0^o/〖90〗^o]〗_n (cross-ply) ultra-high molecular weight polyethylene (UHMWPE) fibre composites with polymeric matrices have been investigated for strain rates in the range 0.01 s^(-1) to 4000 s^(-1). The measured strain rate sensitivity was mild for strain rates less than about 100 s^(-1), but increased sharply at higher rates. X-ray computed tomography and optical microscopy revealed that over the range of strain rates investigated here, the deformation mechanism was kinking (micro-buckling) of the plies with a kink band width of about 1 mm. Ply delamination was also observed, but only during softening phase of the response after the peak strength had been attained. To gain a mechanistic understanding of the observed strain rate sensitivity, finite element (FE) simulations were used to model the compression experiments. For these calculations, each specimen ply was explicitly modelled via a pressure-dependent crystal plasticity framework that accounts for the large shear strains and fibre rotations that occur within each ply in the kink band. Calculations were conducted in the limits of perfectly-bonded and completely un-bonded plies. Good agreement between measurements and predictions was obtained when plies were assumed to be perfectly bonded, confirming the hypothesis that ply delamination plays a small role in setting the peak strength as well as the compressive response of the composite at moderate levels of applied strain. The calculations also show that misalignment of the specimen between the compression platens strongly influences the compression response and especially the initial stiffness. Importantly, the FE calculations reveal that over the range of strain rates investigated here, inertial stabilisation has a negligible contribution to the strong rate sensitivity observed for strain rates above 100 s^(-1) and that this sensitivity is primarily associated with the strain rate sensitivity of the polymeric matrix.Item Open Access Indentation response of a 3D non-woven carbon-fibre composite(Cambridge University Press, 2018-01-16) Das, S.; Kandan, Karthikeyan; Kazemahvazi, S.; Wadley, H. N. G.; Deshpande, V. S.The indentation response of a 3D noninterlaced composite comprising three sets of orthogonal carbon-fibre tows in an epoxy matrix is investigated. The 3D composites have a near isotropic and ductile indentation response. The deformation mode includes the formation of multiple kinks in the tows aligned with the indentation direction and shearing of the orthogonally oriented tows. Finite element (FE) calculations are also reported wherein tows in one direction are explicitly modeled with the other two sets of orthogonal tows and the matrix pockets treated as an effective homogenous medium. The calculations capture the indentation response in the direction of the explicitly modeled tows with excellent fidelity but under-predict the indentation strength in the other directions. In contrast to anisotropic and brittle laminated composites, 3D noninterlaced composites have a near isotropic and ductile indentation response making them strong candidates for application as materials to resist impact loading.Item Open Access Investigation of woven commingled thermoplastic composite for the prosthetic application(2022) Farukh, Farukh; Nagarajan, Yogeshvaran; Kandan, KarthikeyanProsthetic Sockets serve as an integral link between the amputee’s residual limb and the rest of the prosthesis. Focusing on sustainability (recycling and bio-degradable), we explore the suitability of self-reinforced(sr) PLA and PET composite as alternative materials for manufacturing prosthetic sockets. For this purpose, we performed tensile and flexural testing on commingled woven srPLA and srPET composite. The srPLA exhibits elastic-brittle response having an average failure strain of 2%. In contrast, srPET displays elastic-plastic response with average failure strain reaching up to 20%. The tensile and flexural strength of srPET is 132MPa and 72MPa, respectively. This is on par with the standard prosthetic socket materials including Glass and Carbon fibre reinforced composite with thermoset matrix. Therefore, srPET could be the realistic alternative for manufacturing sustainable prosthetic sockets. In contrast, the srPLA has inferior mechanical properties to that of standard prosthetic socket materials. Since the srPLA composite has recyclability and bio-degradability, it can be used to manufacture the test or check sockets; thus reducing the plastic pollution due to discarded check sockets.Item Open Access OUT-OF-PLANE COMPRESSIVE RESPONSE OF ADDITIVELY MANUFACTURED CROSS-PLY COMPOSITES(2018-09-10) Yogeshvaran, R. N.; Liu, B. G.; Farukh, Farukh; Kandan, KarthikeyanDigital manufacturing is employed to 3D print continuous Carbon, Glass and Kevlar fibre reinforced composites in [0°/90°] layup sequence. These 3D printed composites subjected to quasi-static, out-of-plane compression loading. The out-plane compressive strength of the 3D printed Carbon and Glass fibre reinforced composites were independent of specimen size. By contrast, the Kevlar fibre composites have shown a pronounced size effect upon their out-of-plane compressive strength. By using pressure film measurements, it is shown that there exists a shear-lag zone at the periphery of the specimen which governs the out-of-plane compressive strength of the 3D printed composites. To gain further insights on the experimental findings, Finite Element (FE) simulations are carried out using a pressure-dependent crystal plasticity framework. An analytical model is also developed to link the out-of-plane compressive strength of the 3D printed composites to their mechanical properties. Both FE and analytical model accurately predict the out-of-plane compressive strength of 3D printed composites.Item Open Access Out-of-plane compressive response of additively manufactured cross-ply composites(Cambridge University Press, 2020-03-06) Farukh, Farukh; Liu, B. G.; Yogeshvaran, R. N.; Kandan, KarthikeyanDigital manufacturing was employed to 3D print continuous Carbon, Glass and Kevlar fibre reinforced composites in Unidirectional (UD) [0°], Off-axis ±45° and Cross-ply [0°/90°] layup sequence. These 3D printed composites were subjected to quasi-static, in-plane tension and out-of-plane (compression and shear) loading. The tensile strength of 3D printed Carbon, Glass and Kevlar UD laminates was significantly lower than that of 3D printing filaments used to manufacture them. The type of fibre (brittle/ductile) reinforcement was found to be governing the shear yield strength of 3D printed composites despite having the same Nylon matrix in all the composites. Out-of-plane compressive strength of the 3D printed Carbon and Glass fibre reinforced composites was independent of specimen size. Contrary to that, Kevlar fibre composites showed a pronounced size effect upon their out-of-plane compressive strength. A combination of X-ray tomography and pressure film measurements revealed that the fibres in 3D printed composites failed by ‘indirect tension’ mechanism which governed their out-of-plane compressive strength. To gain further insights on the experimental observations, Finite Element (FE) simulations were carried out using a pressure-dependent crystal plasticity framework, in conjunction with an analytical model based on shear-lag approach. Both FE and analytical model accurately predicted the out-of-plane compressive strength of all (Carbon, Glass and Kevlar fibre reinforced) 3D printed composites.Item Open Access Perforation resistance of CFRP beams to quasi-static and ballistic loading: The role of matrix strength(Elsevier, 2017-04-03) Yu, B.; Kandan, Karthikeyan; Deshpande, V. S.; Fleck, N. A.The effect of matrix shear strength on the ballistic response of simply-supported carbon fibre reinforced plastic (CFRP) beams was explored for a flat-ended projectile. To gain insight into the deformation and failure mechanisms, the following additional tests were performed on CFRP beams: (i) quasi-static indentation tests with rigid back support and, (ii) quasi-static cropping tests. In all 3 types of tests, CFRP [0°/90°] cross-ply laminates were tested in six states of cure, such that the matrix shear strength ranges from 0.1 MPa to 100 MPa. In the quasi-static cropping tests, the composite beams failed by shear plugging (involving transverse matrix cracks, ply delamination, and fibre fracture). In contrast, indirect tension (by ply tensile failure in the fibre direction) occurred in the back-supported quasi-static indentation tests. In the ballistic tests, the CFRP beams of high matrix shear strength (30 MPa–100 MPa) failed by a shear plugging mode. When the matrix shear strength was less than 30 MPa, the failure mode and the penetration velocity doubled and occurred by indirect tension. The optimal shear strength to give adequate static and ballistic strength is on the order of 20 MPa.Item Open Access Self-Reinforced Composite Materials: Frictional Analysis and Its Implications for Prosthetic Socket Design(MDPI, 2024-11-18) Nagarajan, Yogeshvaran R.; Hewavidana, Yasasween; Demirci, Emrah; Sun, Yong; Farukh, Farukh; Kandan, KarthikeyanFriction and wear characteristics play a critical role in the functionality and durability of prosthetic sockets, which are essential components in lower-limb prostheses. Traditionally, these sockets are manufactured from bulk polymers or composite materials reinforced with advanced carbon, glass, and Kevlar fibres. However, issues of accessibility, affordability, and sustainability remain, particularly in less-resourced regions. This study investigates the potential of self-reinforced polymer composites (SRPCs), including poly-lactic acid (PLA), polyethylene terephthalate (PET), glass fibre (GF), and carbon fibre (CF), as sustainable alternatives for socket manufacturing. The tribological behaviour of these self-reinforced polymers (SrPs) was evaluated through experimental friction tests, comparing their performance to commonly used materials like high-density polyethylene (HDPE) and polypropylene (PP). Under varying loads and rotational speeds, HDPE and PP exhibited lower coefficients of friction (COF) compared to SrPLA, SrPET, SrGF, and SrCF. SrPLA recorded the highest average COF of 0.45 at 5 N and 240 rpm, while SrPET demonstrated the lowest COF of 0.15 under the same conditions. Microscopic analysis revealed significant variations in wear depth, with SrPLA showing the most profound wear, followed by SrCF, SrGF, and SrPET. In all cases, debris from the reinforcement adhered to the steel ball surface, influencing the COF. While these findings are based on friction tests against steel, they provide valuable insights into the durability and wear resistance of SRPCs, a crucial consideration for socket applications. This study highlights the importance of tribological analysis for optimising prosthetic socket design, contributing to enhanced functionality and comfort for amputees. Further research, including friction testing with skin-contact scenarios, is necessary to fully understand the implications of these materials in real-world prosthetic applications.Item Open Access Shape Analysis of Prosthetic Socket Rectification Procedure for Transtibial Amputees(MDPI, 2024-02-05) Nagarajan, Y. R.; Farukh, Farukh; Silberschmidt, Vadim V.; Kandan, Karthikeyan; Singh, Amit Kumar; Mukul, PoojaAchieving a comfortable socket residual limb interface is crucial for effective prosthetic rehabilitation, depending on the precise characterisation and fluctuations in the shape and volume of residual limbs. Clinicians rely on subjective and iterative methods for shaping sockets, often involving a trial-and-error approach. This study introduces a framework for measuring, analysing, and comparing residual limb shape and volume using scanned data to facilitate more informed clinical decision-making. Surface scans of 44 transtibial residual limb casts of various sizes and lengths were examined. All scans were spatially aligned to a mid-patella and subjected to analysis using a shape analysis toolbox. Geometric measurements were extracted, with particular attention to significant rectified regions during the cast rectification process. Following PTB guidelines, our analysis revealed substantial alterations, primarily in the mid-patella region, followed by the patellar tendon area. Notably, there was a significant volume change of 6.02% in the region spanning from mid-patella to 25% of the cast length. Beyond this point, linear cast modifications were observed for most amputees up to 60% of the cast length, followed by individual-specific deviations beyond this region. Regardless of residual limb size and length, the modifications applied to positive casts suggested categorising patients into five major groups. This study employs the AmpScan shape analysis tool, to comprehend the cast rectification process used for capturing and assessing the extent of rectification on patients’ residual limb casts. The clinical implications of our research are threefold: (a) the comparison data can serve as training resources for junior prosthetists; (b) this will aid prosthetists in identifying specific regions for rectification and assessing socket fit; (c) it will help in determining optimal timing for prosthetic fitting or replacement.Item Open Access Single Polymer Composites: An Innovative Solution for Lower Limb Prosthetic Sockets(MDPI, 2024-04-30) Nagarajan, Yogeshvaran R.; Farukh, Farukh; Buis, Arjan; Kandan, KarthikeyanThe demand for affordable prostheses, particularly in low- and middle-income countries (LMICs), is significant. Currently, the majority of prosthetic sockets are manufactured using monolithic thermoplastic polymers such as PP (polypropylene), which lack durability, strength, and exhibit creep. Alternatively, they are reinforced with consumptive thermoset resin and expensive composite fillers such as carbon, glass, or Kevlar fibres. However, there are unmet needs that amputees face in obtaining affordable prosthetic sockets, demanding a solution. This study utilises self-reinforced PET (polyethylene terephthalate), an affordable and sustainable composite material, to produce custom-made sockets. Advancing the development of a unique socket manufacturing technique employing a reusable vacuum bag and a purpose-built curing oven, we tested fabricated sockets for maximum strength. Subsequently, a prosthetic device was created and assessed for its performance during ambulation. The mechanical and structural strength of PET materials for sockets reached a maximum strength of 132 MPa and 5686 N. Findings indicate that the material has the potential to serve as a viable substitute for manufacturing functional sockets. Additionally, TOPSIS analysis was conducted to compare the performance index of sockets, considering decision criteria such as material cost, socket weight, and strength. The results showed that PET sockets outperformed other materials in affordability, durability, and strength. The methodology successfully fabricated complex-shaped patient sockets in under two hours. Additionally, walking tests demonstrated that amputees could perform daily activities without interruptions. This research makes significant progress towards realising affordable prostheses for LMICs, aiming to provide patient-specific affordable prostheses tailored for LMICs.Item Open Access Strength assessment of PET composite prosthetic sockets(MDPI, 2023-06-26) R. Nagarajan, Yogeshvaran; Farukh, Farukh; V. Silberschmidt, Vadim; Kandan, Karthikeyan; Rathore, Radheshyam; Kumar Singh, Amit; Mukul, PoojaA prosthesis is loaded by forces and torques exerted by its wearer, the amputee, and should withstand instances of peak loads without failure. Traditionally, strong prosthetic sockets were made using a composite with variety of reinforcing fibres such as glass, carbon, and kevlar. Amputees in less- resourced nations can lack access to composite prosthetic sockets due to their unavailability or prohibitive cost. Therefore, this study investigates the feasibility of polyethylene terephthalate (PET) fibre-reinforced composites as a low-cost sustainable composite for producing functional lower-limb prosthetic sockets. Two types of these composites were manufactured using woven and knitted fabric with a vacuum assisted resin transfer moulding (VARTM) process. For direct comparison purposes, traditional prosthetic-socket materials were also manufactured from laminated composite (glass-fibre reinforced (GFRP)) and monolithic thermoplastic (polypropylene (PP) and high-density polyethylene (HDPE)) were also manufactured. Dog-bone-shaped specimens were cut from flat laminates and monolithic thermoplastic to evaluate their mechanical properties following ASTM standards. The mechanical properties of PET-woven and PET-knitted composites were found to be have been demonstrated to be considerably superior to those of traditional socket materials such as PP and HDPE. All the materials were also tested in the socket form using a bespoke test rig reproducing forefoot loading according to the ISO standard 10328. The static structural test of sockets revealed that all met the target load-bearing capacity of 125 kg. Like GFRP, the PETW and PETK sockets demonstrated higher deformation and stiffness resistance than their monolithic counterparts made from PP and HDPE. As a result, it was concluded that the PET-based composite could replace monolithic socket materials in producing durable and affordable prostheses.