Browsing by Author "Grasso, Marzio"
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Item Open Access An Analytical Model for the Identification of the Threshold of Stress Intensity Factor Range for Crack Growth(Hindawi, 2017-01-18) Grasso, Marzio; De Iorio, Antonio; Xu, Yigeng; Haritos, George; Mohin, M.; Chen, Yong KangThe value of the stress intensity factor (SIF) range threshold ( ) for fatigue crack growth (FCG) depends highly on its experimental identification. The identification and application of are not well established as its determination depends on various factors including experimental, numerical or analytical techniques used. A new analytical model which can fit the raw FCG experimental data is proposed. The analytical model proposed is suitable to fit with a high accuracy the experimental data and capable to estimate the threshold SIF range. The comparison between the threshold SIF range identified with the model proposed and those found in literature is also discussed. The identified is found to be quite accurate and consistent when compared to the literature with a maximum deviation of 5.61%. The accuracy with which the analytical model is able to fit the raw data is also briefly discussed.Item Open Access Comparative analysis of various hyperelastic models and element types for finite element analysis(MDPI, 2023-11-22) Lin, Po-Sen; Le Roux de Bretagne, Olivier; Grasso, Marzio; Brighton, James; StLeger-Harris, Chris; Carless, OwenThis study aims to evaluate the precision of nine distinct hyperelastic models using experimental data sourced from the existing literature. These models rely on parameters obtained through curve-fitting functions. The complexity in finite element models of elastomers arises due to their nonlinear, incompressible behaviour. To achieve accurate representations, it is imperative to employ sophisticated hyperelastic models and appropriate element types and formulations. Prior published work has primarily focused on the comparison between the fitting models and the experimental data. Instead, in this study, the results obtained from finite element analysis are compared against the original data to assess the impact of element formulation, strain range, and mesh type on the ability to accurately predict the response of elastomers over a wide range of strain values. This comparison confirms that the element formulation and strain range can significantly influence result accuracy, yielding different responses in various strain ranges also because of the limitation with the curve fitting tools.Item Open Access Delamination migration in CFRP laminates under mode I loading(Elsevier, 2020-02-10) Ramji, Amit; Xu, Yigeng; Yasaee, Mehdi; Grasso, Marzio; Webb, PhilipThis paper focuses on the effect of interfacial fibre orientation and interleaved veil on the delamination migration of carbon fibre reinforced polymer laminates under Mode I loading. Double cantilever beam specimens with midplane interfacial fibre orientations of 0/0, 90/90, 0/90, 0/45 and 90/45 were tested under two conditions: one with interleaved thermoplastic polyphenylene sulfide veil at the midplane and one without. Results show that, except for the 0/0 configuration, all other orientations exhibit varying levels of migration associated with the interfacial fibre orientation and veil interleaving. The apparent fracture toughness determined with the modified compliance calibration method is closely related to the delamination migration and hence a structural energy dissipation measure dependent on interfacial fibre orientation and the interleaved veil. Distributions of the fibre and matrix materials around the delamination front are found to be closely related to the delamination migration behaviour along its path. The experimental observation and rationalisation presented in this paper provide further knowledge regarding delamination migration and its correlation to the apparent fracture toughness, which is of direct relevance to the damage tolerance design of laminated composite componentsItem Open Access Effect of interfacial fibre orientation and PPS veil density on delamination resistance of 5HS woven CFRP laminates under mode II loading(Elsevier, 2021-02-19) Ramji, Amit; Xu, Yigeng; Grasso, Marzio; Yasaee, Mehdi; Webb, PhilipThis paper presents an experimental study on the effect of interfacial fibre orientation and interleaved thermoplastic veil on Mode II interlaminar fracture toughness of 5-harness satin woven carbon fibre reinforced polymer composite laminates. Three-point End-Notched Flexure tests were carried out to determine delamination resistance, GIIC, of specimens with five fibre orientation biases and two veil densities at the midplane. Results show that delamination resistance of 5-harness satin woven laminates depends on the layup configurations at the midplane with 90/45 fibre orientation bias exhibiting the greatest resistance. The delamination resistance enhancement from polyphenylene sulfide (PPS) veil interleaves is also fibre orientation dependent but a further increase of the veil density from 10 gm−2 to 20 gm−2 offers little extra benefit. Fracture surface morphologies were examined under SEM to understand the failure mechanism and fracture process of the woven laminate under the combined effects of the interfacial fibre orientation and the veil density. Fibre orientation relative to the delamination path, surface texture misfit, and veil density are the three main contributors identified for the variation of delamination resistance of 5HS woven laminates.Item Open Access Electrical and mechanical characterisation of poly(ethylene)oxide-polysulfone blend for composite structural lithium batteries(MDPI, 2023-06-05) Gucci, Francesco; Grasso, Marzio; Russo, Stefano; Leighton, Glenn J. T.; Shaw, Christopher; Brighton, JamesIn this work, a blend of PEO, polysulfone (PSF), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was prepared at different PEO–PSf weight ratios (70-30, 80-20, and 90-10) and ethylene oxide to lithium (EO/Li) ratios (16/1, 20/1, 30/1, and 50/1). The samples were characterised using FT-IR, DSC, and XRD. Young’s modulus and tensile strength were evaluated at room temperature with micro-tensile testing. The ionic conductivity was measured between 5 °C and 45 °C through electrochemical impedance spectroscopy (EIS). The samples with a ratio of PEO and PSf equal to 70-30 and EO/Li ratio equal to 16/1 have the highest conductivity (1.91 × 10−4 S/cm) at 25 °C, while the PEO–PSf 80-20 EO/Li = 50/1 have the highest averaged Young’s modulus of about 1.5 GPa at 25 °C. The configuration with a good balance between electrical and mechanical properties is the PEO–PSf 70-30 EO/Li = 30/1, which has a conductivity of 1.17 × 10−4 S/cm and a Young’s modulus of 800 MPa, both measured at 25 °C. It was also found that increasing the EO/Li ratio to 16/1 dramatically affects the mechanical properties of the samples with them showing extreme embrittlement.Item Open Access Electrophoretic deposition of LiFePO4 and carbon black: a numerical study to explore longitudinal trends using Taguchi design(Elsevier, 2024-11) Russo, Stefano; Grasso, Marzio; Huang, Jian; Pramana, Stevin S; Gucci, Francesco; Shaw, Christopher; Leighton, Glenn JDeveloping Electrophoretic Deposition (EPD) for Composite Structural Batteries (CSBs) could revolutionise energy storage technology. CSBs offer an innovative solution by seamlessly integrating batteries into structures and effectively reducing weight and space constraints. Despite its successful implementation across various fields, EPD method still lacks comprehensive understanding of the underlying physical and chemical processes due to the number of variables involved. In this study the effects of key parameters associated with the process are investigated with a coupled FEM and analytical approach to find correlations with the deposition process. A Taguchi Design of Experiment with five parameters, namely voltage, concentration, relative weight ratio of LiFePO4 – carbon black particles, length and perimeter of the electrodes is implemented to identify the correlations with mass deposited, thickness of the coating and yield rate when LiFePO4 and Carbon Black particles in ethanol suspension are used. In order to capture the variation over time, each parameter is studied at six different time of deposition. A concentration that optimises yield rate resulting in thickness and mass deposition is identified. The resistivity of the suspension dictates the yield rate dynamics, allowing it to be designed within a specific range to meet requirements of different applications.Item Open Access Experimental and numerical investigation of heave damper hydraulic seal for racing car(Elsevier, 2022-06-29) Azar, Michel; Grasso, Marzio; Rose, Timothy; Carless, Owen; St Leger-Harris, Chris; Lawson, CarlThis article presents a combined experimental and numerical approach to analyse the failure of a heave damper hydraulic seal for racing car. The post-mortem analysis of the damaged seals was carried out with both optical microscopy and finite element analysis using material test data from Dynamic Modulus Analyser (DMA). The stress in the seal and damper was simulated modelling each step including the press-fitting on the piston, the interference with the cylinder and the oil pressure due to the service. The combination of the evidence collected from the numerical simulation and the observation of the surface damages on the seals proved that the cause of failure was the insufficient lubrication during high frequency, short stroke applications since these working conditions induce oil film break. The detailed damage mechanisms have been identified and explained and an alternative seal design that requires further study and testing in this application has been proposed.Item Open Access Implementation of a finite element modelling strategy for the prediction of aircraft tyre response(SAGE, 2023-03-11) Ramji, Amit; Grasso, Marzio; Chase, James; Maqbool, Hasher; Krypciak, Michal; Merchante, Veronica; Brighton, JamesThis paper presents the finite element modelling (FEM) strategy to identify the structural response of aircraft tyres under quasi-static and taxiing load conditions. The tyre FEM was developed to simulate the aircraft tyre/ground interaction for a range of inflation pressures under vertical, lateral, longitudinal, torsional, yawed and un-yawed rolling. A thorough comparison for validation purposes is made between the test and simulation data extracted from the FEM. The reinforcement plies of the tyres are modelled in a computationally efficient manner whilst also considering the variable fibre volume fractions and ply discontinuities within the tyre. The accurate material characterisation at coupon level combined with the overall modelling approach allowed most simulated responses to match the experimental stiffness within 12% against best fit curves of similar tyre types and within 5% for the majority of test comparisons.Item Open Access Influence of heat treatment-induced residual stress on residual fatigue life of railway axles(Elsevier, 2020-08-03) Pokorny, Pavel; Dlhý, Pavol; Poduska, Jan; Fajkoš, Rostislav; Vojtek, Tomáš; Nahlik, Lubos; Grasso, Marzio; Hutař, PavelAssessment of residual fatigue life of railway axles commonly does not include effect of residual stress. This paper presents advanced methodology for estimation of residual fatigue life of railway axles considering not only external loading but also internal residual stresses. The studied axles made of the EA4T steel were treated by induction hardening in order to generate very high compressive residual stress in the surface layer of the axle. Such residual stress has positive effect on behaviour of surface defects and leads to fatigue crack retardation or even crack arrest and, consequently, to immense prolongation of residual fatigue life. Experimentally measured data of residual stress were implemented in a numerical model in order to determine the true stress state in the axle. The model included a crack and took the effects of bending, press fit and residual stress into account. Residual fatigue life was calculated for various starting crack lengths based on the experimentally determined da/dN-ΔK curves for various load ratios. Finally, the results for axles hardened by standard method and by induction hardening were compared with residual fatigue lives obtained experimentally from fatigue tests on real railway axles with artificial cracks. The calculated values were conservative with good agreement with experimental dataItem Open Access Innovative pultruded composite mast design for railway overhead line structures(MDPI, 2023-06-16) Grasso, Marzio; Robinson, Mark; Chaffey, Brace Chaffey; Mortimer, Philip; Brighton, JamesThe structural feasibility of using a pultrusion of carbon-fibre-reinforced polymers (CFRP) for the lightweight design of a mast for overhead line railway electrification was investigated and simulated. Material characterisation was undertaken using three-point bending and finite element analysis to identify the orthotropic properties of the pultruded tubes designed for a composite mast for overhead electrification. An innovative design of the mast was proposed and verified using a simulation that compared the deflection and stress levels under wind and inertial load. From the simulation results, it was concluded that the proposed composite structure design complies with the mechanical performance requirements for its implementation and benefits the application with a weight reduction of more than 80% with respect to the current steel mast design.Item Open Access Low-velocity impact behaviour of woven laminate plates with fire retardant resin(Elsevier, 2019-04-27) Grasso, Marzio; Xu, Yigeng; Ramji, Amit; Zhou, Gang; Chrysanthou, Andreas; Haritos, George; Chen, Yong KangThe understanding of the damage mechanisms for woven laminate plates under low-velocity impact is challenging as the damage mechanisms at the interface of adjacent layers are dominated by the fibre architecture. This work presents an experimental investigation of the behaviour of woven glass and carbon fibre composite laminates in a matrix of fire retardant resin under low-velocity impact. The performance is evaluated in terms of damage mechanisms and force time history curves. Six impact energy levels were used to test standard plates to identify the type of damage observed at various energy levels. Scanning electron microscopy (SEM) along with C-scans were used to characterise the damage. It has been observed that in woven composites, the damage occurs mostly between the fibre bundles and matrix. As the impact energy increases, the failure involves extended matrix cracking and fibre fracture. Moreover, due to the fibre architecture, both the contact forces between bundles of fibres and stretching of the bundles are responsible for the dominant matrix cracking damage mode observed at the low-impact energy level. As the impact energy increases, the damage also increases resulting in fibre fracture. The experimental evidence collected during this investigation shows that for both the carbon fibre and the glass fibre woven laminates the low-velocity impact behaviour is characterised by extended fibre fracture without a noticeable sudden load drop.Item Open Access Mixed mode fatigue crack propagation behaviour of aluminium F357 alloy(Elsevier, 2018-04-05) Grasso, Marzio; Xu, Yigeng; Russo, Roberto; Rosiello, VincenzoManufacturing defects are often not in the plane perpendicular to the loading direction and will propagate under mixed mode fatigue loading condition. This paper presents a numerical study of mixed mode crack growth behaviour in H-shaped specimens made of aluminium F357 alloy. The size and orientations of the crack are based on the fractographic observation of defects in F357 specimens manufactured by foundry. Equivalent values of the stress intensity factor (SIF) and the maximum circumferential tensile stress criterion have been adopted to simulate growth of cracks at angles of 90°, 60° and 45° to the loading direction, respectively. Mixed mode fatigue crack growth behaviours are analysed in terms of the shape of crack front, SIF variation, and kink angle. The mixity of SIFs of three modes is complex at early stage of growth with the maximum mode III SIF value at the two ends and the maximum mode II SIF value at the middle of the crack front. The crack surface rotates during the mixed mode crack growth, becoming normal to the loading direction regardless of the initial orientation of the crack. The simulated crack front agrees well with the final elliptical shape of the crack front observed in the physical test specimens. The initial crack orientated at 45° to the loading direction has the longest fatigue life compared with other two crack orientations.Item Open Access Numerical simulation of plasticity in double lap metallic bolted joints(Taylor and Francis, 2023-02-08) Grasso, Marzio; Bai, Yuanli; Brighton, James; Carless, Owen; St Leger-Harris, ChrisThis article aims to compare three plasticity models, namely Bai-Wierzbicki (BW), von Mises and Drucker Prager, to predict the failure modes in double-lap metallic bolted joints under shear loading. The double-lap bolted joint finite element model has been validated against literature data, which demonstrated the application of BW ductile fracture model to bolt joint failure prediction. Taguchi Design is used to investigate the effects of geometrical parameters, preload and stress triaxiality on the failure modes. Force–displacement response amongst the three models differs up to 20% when failing in shear and a different prediction of the failure mode (shear out vs. net section) under the same loading and geometry conditions is observed.Item Open Access On a numerical methodology to assess the fatigue life of connecting rods(SAGE, 2023-06-18) Xu, Wentao; Le Roux de Bretagne, Olivier; Grasso, Marzio; Harrison, Matthew F.; Carless, Owen; St Leger-Harris, ChrisAlthough simulation-based fatigue analysis is a standard tool adopted in every sector including automotive industry, the design of engine components in automotive and motorsport applications mostly relies on simplified design approaches supported by time-consuming testing programs. This manuscript proposes a new methodology based on individual engine speed damage estimation and engine speed time history combined with Palmgren-Miner linear damage rule to predict the fatigue state of the connecting rod. The track data, engine multibody simulation (AVL ExciteTM) and engine combustion simulation (AVL BoostTM) are used to generate the initial variable trace that is processed to obtain the block programs. Stress amplitude estimated with finite element analysis (Abaqus) are used to estimate the damage from S-N curve and the cumulative damage is estimated with Palmgren-Miner cumulative damage model. The method proposed is demonstrated using a connecting rod case study and the duty cycle from the race on Sebring international raceway. This work shows the suitability of the approach and the benefit in terms of accuracy in the prediction of the fatigue life.Item Open Access PEO-based polymer blend electrolyte for composite structural battery(Taylor and Francis, 2023-02-22) Gucci, Francesco; Grasso, Marzio; Shaw, Christopher; Leighton, Glenn; Marchante Rodriguez, VeronicaHigh mechanical strength and ionic conductivity of solid-state electrolyte (SSE) are currently conflicting targets that are very difficult to achieve. Polyethylene oxide (PEO) is one of the most common polymers adopted for SSE because of its very high ionic conductivity, but its mechanical strength is very low. This work discusses the manufacturing and testing of PEO blends using polysulfone (PSf) and Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to assess the mechanical response under microtensile testing and the ionic conductivity with electrochemical impedance spectroscopy (EIS). Mechanical tests demonstrated a beneficial effect of LiTFSI with significant increase in maximum stress and ductility measured as strain at failure. The blending of PEO and PSf showed promising conductivity values at room temperature with the 90–10 PEO-PSf composition achieving the highest value (1.06 × 10−6 S/cm) and for the 70–30 composition achieving the highest maximum stress (3.5 MPa) with a conductivity of 3.12 × 10−7 S/cm.Item Open Access Stress analysis of gun breech block for gun design applications(DEStech Publications Inc., 2025-05-19) Abid, Rabia; Appleby-Thomas, Gareth J.; Goyder, Hugh; Grasso, Marzio; Hameed, Amer; Carlucci, Don; Uhlig, W. CaseyThis study presents a detailed Finite Element Analysis (FEA) of a breech block featuring a buttress thread, aimed at understanding the stress distribution under various loading conditions. Buttress threads, known for their high load-bearing capacity and asymmetrical profile, are commonly used in applications where high axial loads are required, such as in hydraulic systems and fasteners. Utilizing Abaqus, a comprehensive stress analysis was conducted on the threaded block to assess critical factors such as stress concentration, deformation patterns, and the overall integrity of the design under different loading scenarios. The model was created using precise geometric definitions of the buttress thread, including the lead angle and asymmetric thread profiles. The material properties were assigned based on realistic parameters commonly used in industrial applications, this material was steel 4340. Static loading conditions were applied to simulate operational stresses, and a fine mesh was employed to capture the detailed stress distribution around the thread roots and flanks, where stress concentrations are typically highest. The results revealed that the buttress thread design effectively distributes axial loads along the inclined surface, minimizing stress concentrations compared to conventional thread forms. This design of the breech block based on the buttress thread is extremely important when it comes to the gun design and it is a good reason why the buttress thread is design in this way for most guns. However, significant stress concentration was observed at the root of the thread, necessitating potential design optimizations. This analysis demonstrates the efficacy of buttress threads for highload applications in gun designs, with the FEA results providing valuable insights for further refinement of the design. The study validates the use of Abaqus in performing detailed stress analysis of complex geometries, showcasing its capability to predict critical stress regions and potential failure points. Recommendations for future work include fatigue analysis and exploring the effects of varying thread dimensions on stress distribution to judge the novelty in our work.Item Open Access Surface damage in woven carbon composite panels under orthogonal and inclined high-velocity impacts(MDPI, 2022-09-26) Marchante Rodriguez, Veronica; Grasso, Marzio; Zhao, Yifan; Liu, Haochen; Deng, Kailun; Roberts, Andrew; Appleby-Thomas, Gareth J.The present research is aimed at the study of the failure analysis of composite panels impacted orthogonally at a high velocity and with an angle. Woven carbon-fibre panels with and without external Kevlar layers were impacted at different energy levels between 1.2 and 39.9 J. Sharp and smooth gravels with a mass from 3.1 to 6.7 g were used to investigate the effects of the mass and the contact area on the damage. Optical microscopy and thermography analyses were carried out to identify internal and surface damage. It was identified that sharp impactors created more damage on the impacted face of the panels, while the presence of a Kevlar layer increased the penetration limit and reduced the damage level in the panel at a higher energy.Item Open Access Technical pathways for distributed recycling of polymer composites for distributed manufacturing: Windshield wiper blades(Elsevier, 2020-03-11) Dertinger, Samantha C.; Gallup, Nicole; Tanikella, Nagendra G.; Grasso, Marzio; Vahid, Samireh; Foot, Peter J. S.; Pearce, Joshua M.Centralized waste plastic recycling is economically challenging, yet distributed recycling and additive manufacturing (DRAM) provides consumers with direct economic incentives to recycle. This study explores the technical pathways for DRAM of complex polymer composites using a case study of windshield wiper blades. These blades are a thermoplastic composite made up of a soft (flexible) and hard (less flexible) material. The distributed manufacturing methods included mechanical grinding to fused granular fabrication, heated syringe printing, 3-D printed molds coupled to injection molding and filament production in a recyclebot to fused filament fabrication. The particle size, angle of repose, thermal and rheological properties are characterized for the two sub-materials to define the conditions for the extrusion. A successful pathway for fabricating new products was found and the mechanical properties of the resultant components were quantified. Finally, the means to convert scrap windshield wiper blades into useful, high-value, bespoke biomedical products of fingertip grips for hand prosthetics was demonstrated. This study showed that the DRAM model of materials recycling can be used to improve the variety of solutions for a circular economy.Item Open Access Threshold identification and damage characterization of woven gf/cf composites under low-velocity impact(MDPI, 2022-10-11) Grasso, Marzio; Xu, YigengThe Delamination Threshold Load (DTL) is a key parameter representing damage resistance of a laminate and is normally identified by locating a sudden drop in the impact force-time history for the laminate made of unidirectional layers. For the woven composite, however, their failure mechanisms appear different and the current literature is not providing any clear procedure regarding the identification of the delamination initiation, as well as the evolution of the failure mechanisms associated with it. In this paper, experimental data have been collected using woven glass and carbon fiber composites. The results are analyzed in terms of force-time and force-displacement curves. While delamination and other damages were clearly observed using ultrasonic scans, the analysis of the results does not reveal any trend changes of the curves that can be associated with the incipient nucleation of delamination. A preliminary discussion regarding the nature of the mechanisms through which the delamination propagates in woven composite and a justification for the absence of a sudden change of the stiffness have been presented. It raises a question on the existence of DTL for woven composites under low velocity impact.