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Medical device‐related pressure ulcers (PUs) (injuries) are a subclass of PUs, associated with pressure and/or shear applied by a medical device onto the skin. Clinical application of a cyanoacrylate liquid skin protectant (CLSP) under the contours of skin‐contacting medical devices to shield an intact skin from the sustained mechanical loads that are applied by medical devices is a preventative option, but no computer modelling work has been reported to assess the biomechanical efficacy of such interventions. Here, we investigated the biomechanical protective effect of a polymerised cyanoacrylate coating using three‐dimensional, anatomically realistic finite element models of the ear with oxygen cannula and the mouth with endotracheal attachment device, informed by experimental studies. We have compared tissue stress exposures under the devices at these facial sites between conditions where the cyanoacrylate skin protectant has been applied or where the device was contacting the skin directly, without the shielding of the cyanoacrylate coating. The CLSP considerably reduced the skin stress concentration levels and overall tissue stress exposures under the aforementioned medical devices. This demonstrates strong biomechanical effectiveness of the studied cyanoacrylate‐based skin protectant in prevention of facial medical device‐related injuries at small, curved and thereby difficult to protect facial sites. [ABSTRACT FROM AUTHOR]

Electrical stimulation of cells allows exogenous electric signals as stimuli to manipulate cell growth, preferential orientation and bone remodelling. In this study, commercially pure titanium discs were utilised in combination with a custom-built bioreactor to investigate the cellular responses of human mesenchymal stem cells via in-vitro functional assays. Finite element analysis revealed the homogeneous delivery of electric field in the bioreactor chamber with no detection of current density fluctuation in the proposed model. The custom-built bioreactor with capacitive stimulation delivery system features long-term stimulation with homogeneous electric field, biocompatible, sterilisable, scalable design and cost-effective in the manufacturing process. Using a continuous stimulation regime of 100 and 200 mV/mm on cp Ti discs, viability tests revealed up to an approximately 5-fold increase of cell proliferation rate as compared to non-stimulated controls. The human mesenchymal stem cells showed more elongated and differentiated morphology under this regime, with evidence of nuclear elongation and cytoskeletal orientation perpendicular to the direction of electric field. The continuous stimulation did not cause pH fluctuations and hydrogen peroxide production caused by Faradic reactions, signifying the suitability for long-term toxic free stimulation as opposed to the commonly used direct stimulation regime. An approximate of 4-fold increase in alkaline phosphatase production and approximately 9-fold increase of calcium deposition were observed on 200 mV/mm exposed samples relative to non-stimulated controls. It is worth noting that early stem cell differentiation and matrix production were observed under the said electric field even without the presence of chemical inductive growth factors. This manuscript presents a study on combining pure titanium (primarily preferred as medical implant materials) and electrical stimulation in a purpose-built bioreactor with capacitive stimulation delivery system. A continuous capacitive stimulation regime on titanium disc has resulted in enhanced stem cell orientation, nuclei elongation, proliferation and differentiation as compared to non-stimulated controls. We believe that this manuscript creates a paradigm for future studies on the evolution of healthcare treatments in the area of targeted therapy on implantable and wearable medical devices through tailored innovative electrical stimulation approach, thereby influencing therapeutic conductive and electroactive biomaterials research prospects and development. [Display omitted] [ABSTRACT FROM AUTHOR]

Pressure ulcers (PUs) are a major public health challenge, having a significant impact on healthcare service and patient quality of life. Computational biomechanical modelling has enhanced PU research by facilitating the investigation of pressure responses in subcutaneous tissue and skeletal muscle. Extensive work has been undertaken on PUs on patients in the seated posture, but research into heel ulcers has been relatively neglected. The aim of this review was to address the key challenges that exist in developing an effective FE foot model for PU prevention and the confusion surrounding the wide range of outputs reported. Nine FE foot studies investigating heel ulcers in bedrest were identified and reviewed. Six studies modelled the posterior part of the heel, two included the calf and foot, and one modelled the whole body. Due to the complexity of the foot anatomy, all studies involved simplification or assumptions regarding parts of the foot structure, boundary conditions and material parameters. Simulations aimed to understand better the stresses and strains exhibited in the heel soft tissues of the healthy foot. The biomechanical properties of soft tissue derived from experimental measurements are critical for developing a realistic model and consequently guiding clinical decisions. Yet, little to no validation was reported in each of the studies. If FE models are to address future research questions and clinical applications, then sound verification and validation of these models is required to ensure accurate conclusions and prediction of patient outcomes. Recommendations and considerations for future FE studies are therefore proposed. • Nine FE foot models for pressure ulcer prevention in bedrest exist, yet all produce conflicting results. • It is difficult to draw clear clinical conclusions due to the methodological limitations. • Internal soft tissue strains are influenced by foot posture, slope and stiffness of the mattress. • The limited number of studies emphasise the need for further research in order to provide valuable clinical conclusions. • Recommendations for future FEA of the foot in bedrest are presented. [ABSTRACT FROM AUTHOR]

This study presents the seepage patterns of earth-fill dams, using critical situations by employing the finite element approach. The Nai Gaj dam is 65km northwest of Dadu city in Sindh Province, Pakistan. In this study, the seepage through the main dam body and foundation is computed and simulated for different scenarios, i.e. maximum, normal, and minimum reservoir level. Seepage analysis was conducted by using the SEEP/W sub-program of GEO-SLOPE software. Dam design parameters and dam geometry data were used as input data to compute the unknown seepage. The seepage behavior of the Nai Gaj dam is shown in terms of net flow which consists of equipotential lines, streamlines, velocity vectors, and phreatic lines. The results show the seepage flux, maximum seepage, and exit gradient at different reservoir levels. The results show that the average flow rate at normal, maximum, and minimum reservoir levels are 1.49×10-7cumec/m, 3.38×10-7cumec/m, and 2.108×10-8cumec/m respectively. In addition, the overall stability of the side slope of the dam is discussed. [ABSTRACT FROM AUTHOR]

The Gurson–Tvergaard–Needleman damage model (GTN) describes the three stages of ductile tearing of steel: nucleation, growth and coalescence of micro-voids. This work is divided into two main parts. In the first part, based on the inverse analysis and the comparison between the experimental and numerical data, the parameters of the GTN damage model in conjunction with the hardening law are determined. The identification is broadened to include a considerable number of experimental tests drawn from our previous works and other works done at ALFAPIPE Ghardaia laboratory. In the second part, an Artificial Neural Network model is developed to predict the parameters of the (GTN) model coupled with the hardening law that goes through the prediction of traction and impact properties of API X70 steel pipe depending on its chemical composition. The weight of the chemical elements in percentages is considered as the inputs and the GTN parameters are considered as the outputs. In order to validate the obtained ANNGTN parameters, traction and impact tests are simulated. The numerical results are compared with the experimental ones and revealed that the developed model is very precise and has the potential to capture the interaction of GTN parameters coupled with hardening law and chemical composition of steel pipelines. [ABSTRACT FROM AUTHOR]

The dynamic backcalculation of pavement layer properties, and more specifically the ability to determine the asphalt concrete master curve, using Falling Weight Deflectometer (FWD) data has caught the attention of many researchers for years. The damaged or aged master curve of existing pavement structures allows the accurate prediction of the pavement structural capacity and remaining life – a goal that cannot be achieved through laboratory testing. To address this need, the authors developed a dynamic backcalculation application that employs the ABAQUS software for forward calculation using implicit dynamic analyses, and the Newton-Raphson's root-solving algorithm for optimisation. The capabilities of the application were demonstrated for three simulated flexible pavement structures and two asphalt concrete mixes using 40 combinations. The asphalt concrete moduli at the FWD most dominant frequencies around 17 Hz, and the variables of unbound layers converged to the exact values in few iterations for all combinations. The master curves, and mainly the maximum moduli, were reliably determined to less than 1% and 4% error for about 60% and 85% of the combinations, respectively. The potential for determining the master curve and maximum modulus was shown to be dependent on the asphalt concrete mix, asphalt concrete temperature and pavement structure. [ABSTRACT FROM AUTHOR]

In this work a modelling approach for predicting density distribution in the vicinity of two facing grooves on a parallelepiped compact surface, is developed and results are validated using X-ray tomography. An experimental hybrid procedure is proposed to calibrate Drucker-Prager Cap model material parameters which are numerically validated and considered for FEM compaction simulation of grooved specimen using Arbitrary Lagrangian Eulerian method (ALE). Results of the predicted density show high values under the groove and low values on its flanks and shoulders. Similar findings were observed in the literature. Additionally, a strong density gradient between the facing grooves is predicted and validated, demonstrating that the calibrated model achieved good agreements with the measurements. The proposed hybrid calibration procedure could be used for other shape and size die not benefiting from radial instrumentation. Moreover, the ALE approach demonstrated its robustness in solving die powder compaction in presence of strong mesh distortions. [Display omitted] • Hybrid procedure for DPC model material parameters calibration. • Finite Element Modelling of die compaction using ALE adaptive meshing approach. • Density distribution predictions in the vicinity of grooved parallelepiped compact. • Validation of density distribution using X ray tomography. [ABSTRACT FROM AUTHOR]

Recent observations of failure and damage of buildings and structures under seismic action has led to an increasing interest for an in‐depth analysis of the vertical component of site ground motion. In particular, when dealing with saturated soils, the current engineering practice does not usually go beyond the simplified u–p formulation of the Biot's equations describing the coupled hydro‐mechanical behaviour, thus neglecting some terms of fluid inertial forces, despite the presence of more refined formulations, for example, the u–U formulation. Therefore, a theoretical and numerical validation of the u–p formulation as compared with the u–U formulation is proposed in this work, where the numerical simulations are compared with the analytical solution for the u–p formulation, which is also derived and illustrated in this text. The comparison between the two formulations and the analytical solution is provided for different levels of permeability and dynamic actions, which are representative of a wide scenario of site ground properties and seismic hazard in the vertical direction. In particular, the soil response is analysed in terms of acceleration and pore pressure time history, frequency content, acceleration response spectrum, and amplification ratio of acceleration. This study extends the discussion of the limits of applicability of the u–p formulation with respect to the rigorous solution of Biot's equations (obtained here with u–U formulation) to the context of a complex dynamic regime provided by the vertical components of real earthquake records, and paves the way for further investigations. [ABSTRACT FROM AUTHOR]

Experience in the United Arab Emirates (UAE) has revealed the settlement risk to foundations built on collapsible strata when such strata become increasingly wet due to irrigation of lawns. This paper presents a numerical analysis of ground settlement at a location in the UAE where structural damage occurred, prompting a forensic investigation that involved borehole drilling and measurement of subsidence and structural failure characteristics. MidasTM 3D finite element programme is used with field information from boreholes and irrigation specifications to simulate and predict the settlement profile for a typical pair of residential villas surveyed. Important factors are taken into account including the depths and thicknesses of the collapsible strata, the in-situ stresses, transient water flow, irrigation cycles, water table depth and the soil-structure mechanical properties. The maximum settlement of the boundary wall is predicted to be 157 mm, which agrees closely with the measured value of 165 mm. In addition, the predicted surface displacements are consistent with the observed ground and boundary wall deformation patterns. [ABSTRACT FROM AUTHOR]

The recent Laxmanpuri landslide of Mussoorie area is one of the major landslide events in the Uttarakhand Himalaya. The landslide occurred in July 2016, in proximity to Civil Hospital Quarters and Mussoorie Veterinary Hospital buildings on the Mussoorie-Chamba road. The landslide had caused serious environmental and socio-economic problems as part of the road segment along with nearby buildings being severely damaged. Though it was categorized solely as a rain-induced landslide, the Laxmanpuri area in the vicinity of the landslide location has undergone significant anthropogenic exploitation in terms of building and road construction in recent times. The proximity of landslide to civil structures and recent history of anthropogenic activities make a strong reason for detailed stability evaluation. Therefore, an engineering geological investigation and comparison based on pre- and post-event stability analyses has been carried out to derive its failure mechanism, causes and also to assess the present stability condition. This study uses finite element modelling with shear strength reduction technique for stability analysis. In the pre-event stability analysis, the slope was found to be unstable (with factor of safety < 1), and the shear strain and displacement are confined to the shallow overburden. While in the post-event stability analysis, the landslide-affected slope was found to be stable with a factor of safety of > 2. The rise in factor of safety in the post-event stability analysis may be attributed to the fact that the unstable shallow overburden mass got translationally moved down, exposing the competent in-situ quartzite rock on the slope. The investigation revealed this to be a translational failure involving shallow overburden material triggered by rainfall. The anthropogenic activities involving deep excavation for road construction and improper discharge of wastewater from the surrounding buildings over the landslide-affected slope had derailed the equilibrium condition of the slope, causing failure during rains. [ABSTRACT FROM AUTHOR]

The paper is devoted to the comparison of different types and different values of coils for inductive power transfer in the classical circuit. This topic is relevant with the growing demand and interest in wireless chargers and the diversity of inductance coils for wireless power transfer. The main geometric parameters affecting the coil efficiency are determined. For experimental verification the classical scheme for wireless power transfer is used based on a full-bridge inverter. Different coils at different distance between them, lateral misalignment and load resistance changed are tested. It is determined that single-layer coils have better transmit-receive efficiency than double-layer ones, especially with series-series compensation topology. The application of two-layer coils is recommended in case of high input current. The investigated samples have efficiency at the level of industrial standards. The design approach can be used for any level of power and application, including wireless charging of electric vehicle batteries.

This research aims at comparing the thermal performance of walls made from traditional and alternative building materials. The experimental study involves five types of walls were studied based on perforated ceramic bricks and a mixture of clay, sand with various straw proportions. Specialized software and the finite element method (FEA) were employed for modelling of the thermal processes and their visualization for the different types of walls. A simulation modelling algorithm was developed. The models developed show very good convergence of the results and provide for subsequent design and thermal calculation of constructions made by environmentally friendly materials.

The aim of this paper is to propose a theoretical meso-model describing the nonlinear behaviour of filament wound glass–polyester composite structures based on a progressive damage and failure analysis. This model has been implemented in the finite element modelling software Abaqus through the user material subroutine and then validated by experimental investigations. Numerical results have been compared with experimental data obtained from a set of tests on representative specimens using the strain measurement technique.

This work studied the interface morphology, microstructure behavior, and mechanical properties of the fabricated trilayered Cu/Al8011/Al1060 composite. In this regard, the roll-casted Cu/Al8011 bimetal was subjected to the hot-roll-bonding process with Al1060 at a thickness reduction of 47%. As a result, the hot-roll-bonding broke the produced nonuniform continuous interface within the copper and aluminum during the roll-casting process. The corresponding interface from the copper side includes Al4Cu9, AlCu, and Al2Cu, respectively. Additionally, SEM-based in-situ tensile deformation revealed that the initiated cracks at the Cu/Al8011 interface propagated into the copper layer that led to its fracture before the aluminum. Based on the FEM results, the effective stress distribution of the Cu strip is not homogeneous at the deformation zone. Moreover, the thickness reduction of the Cu and Al layers was respectively lower and slightly higher than that of the trilayered composite, indicating that plastic deformation mainly occurred at the aluminum matrix due to its large plasticity amount.

The paper presents the analysis of strength and stiffness of metric threaded steel rods glued in glulam obtained by using two different gluing methods. The first method is used when the threaded steel rod is glued into a groove larger than the rod’s diameter, while the second method is applied when the diameter of the groove is smaller than the diameter of the threaded steel rod. The steel rod is covered with glue before it is inserted into the smaller diameter groove. The first method investigates the 2-mm-thick glue-line, while the second method analyses the contact when the groove’s diameter is 2 mm smaller than the outer diameter of the rod. Epoxy-type resin is used for both gluing methods. Different gluing methods present different interactions between the steel rod and glulam which result in different failure modes. The second method presents a plastic failure between the steel rod and glulam caused by the local compression and shear of glulam. The presented studies are made using metric threaded steel rods of diameters M12 and M16. In total, 20 specimens are experimentally tested in tension-to-tension tests performed according to EN 26891. The interaction between glulam and glued steel rods is also investigated using the 3D finite element modelling. The results obtained using the proposed 3D finite element model with different contact conditions between steel and glulam and the failure criterion for timber shear are well in line with the experimental findings.

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

In systems transporting fluids like petrol, water, or any fluids. Copper and brass pipes are used because of the capability to resist corrosion. The copper alloys can be welded by several methods like arc, resistance, friction welding, and gas methods and they can be readily soldered and brazed. In the present study, mechanical properties and finite element modeling evaluation for friction stir welding of two dissimilar pipes (C12200 copper alloy pipe with C36000 copper alloy pipe). During this study six parameters were used where rotation speed of (775,1000,1300 and1525rpm), welding speed of 1.7 mm/min, axial force of 8.5KN, with a CW direction of rotation, and zero degree of tilt angle, using a threaded cone geometry of the tool. The results showed that the best weld quality was in case when the speed of rotation was 1525 rpm

Abstract Efficient identification of effective neurostimulation strategies is critical due to the growing number of clinical applications and the increasing complexity of the corresponding technology. In consequence, investigators are encouraged to accelerate translational research of neurostimulation technologies and move quickly to clinical applications. However, this process is hampered by rigorous, but necessary, regulations and lack of a mechanistic understanding of the interactions between electric fields and neural circuits. Here we discuss how computational models have influenced the field of neurostimulation for pain and movement recovery, deep brain stimulation, and even device regulations. Finally, we propose our vision on how computational models will be key to accelerate clinical developments through mechanistic understanding.

Background and Purpose: Associations between dose and rectal toxicity in prostate radiotherapy are generally poorly understood. Evaluating spatial dose distributions to the rectal wall (RW) may lead to improvements in dose-toxicity modelling by incorporating geometric information, masked by dose-volume histograms. Furthermore, predictive power may be strengthened by incorporating the effects of interfraction motion into delivered dose calculations.Here we interrogate 3D dose distributions for patients with and without toxicity to identify rectal subregions at risk (SRR), and compare the discriminatory ability of planned and delivered dose. Material and Methods: Daily delivered dose to the rectum was calculated using image guidance scans, and accumulated at the voxel level using biomechanical finite element modelling. SRRs were statistically determined for rectal bleeding, proctitis, faecal incontinence and stool frequency from a training set (n = 139), and tested on a validation set (n = 47). Results: SRR patterns differed per endpoint. Analysing dose to SRRs improved discriminative ability with respect to the full RW for three of four endpoints. Training set AUC and OR analysis produced stronger toxicity associations from accumulated dose than planned dose. For rectal bleeding in particular, accumulated dose to the SRR (AUC 0.76) improved upon dose-toxicity associations derived from planned dose to the RW (AUC 0.63). However, validation results could not be considered significant. Conclusions: Voxel-level analysis of dose to the RW revealed SRRs associated with rectal toxicity, suggesting non-homogeneous intra-organ radiosensitivity. Incorporating spatial features of accumulated delivered dose improved dose-toxicity associations. This may be an important tool for adaptive radiotherapy in the future.

In this paper the authors detail the possibilities of modelling of finite element method (FEM) of glued insulated rail joints which are applied in railway tracks with continuously welded rails (CWR). A lot of laboratory tests (static and dynamic 3-point bending tests, axial pulling tests) were executed on glued insulated rail joints, the specimens were related to three different rail profiles applied in Hungary: MÁV 48.5; 54E1 (UIC54), 60E1 (UIC60), respectively. The static bending tests with many bay length values were conducted, before and after dynamic (fatigue) tests. 2-D beam models were made in FEM software using semi-rigid hinge as the simplified connection of fishplated glued insulated rail joint. The FEM models were calibrated and then validated with the static vertical displacement values in the middle-bay position measured in laboratory. The model validation was conducted with two methods.

Nano-indentation with spherical indenters is a test technique largely used to determine the elastic–plastic behavior of a very small volume of material. In this work, the indentation size effects under spherical indentation were investigated for Fe9Cr model alloys and reduced activation tempered martensitic steel Eurofer97. Experimental tests and finite element method (FEM) simulations were performed. Results and analysis of the experimental results and FEM simulations revealed that the indentation size effects depend on both the spherical indenter radius and the microstructures characterized by the initial dislocation density and the grain size of the tested materials. The observed difference in the indentation stress–strain curves was qualitatively discussed in terms of the relative effects associated with the ball radius and the microstructural length scale.

The mechanism of bitemporal hemianopia arising as a result of chiasmal compression is unknown. In this study, we combined an ex vivo experiment and finite element modelling (FEM) to investigate its potential mechanism. A cadaveric human optic chiasm was scanned using micro-CT before and after deformation by inflation of Foley catheter, to simulate tumour growth from beneath. The geometry of the same chiasm was reconstructed and simulated using finite element analysis. Chiasmal deformations were extracted from the simulation and compared with those observed during micro-CT scanning. In addition, nerve fibre models examining variation in local fibre distribution patterns of the chiasm were incorporated to investigate the strain (deformation) distributions of the chiasm at an axonal level. The FEM model matched the micro-CT scans well both qualitatively and quantitatively. Compression of the chiasm induced high strains in the paracentral portions of the chiasm where the crossing optic nerve fibres are located. At an axonal level, the magnitude of strains affecting crossed fibres were greater than those affecting uncrossed fibres. The high strains in the paracentral portions of the chiasm, combined with the differences in strain between crossed and uncrossed nerve fibres, are consistent with a biomechanical explanation for the pattern of visual field loss seen in chiasmal compression.

As the current obesity epidemic grows, an increased number of obese patients undergoing Total Hip Arthroplasty (THA) can be expected in the coming years. The National Health Service of the UK (NHS) recommends that an obese patient should undergo weight loss before THA. It is understood that an increased body weight would increase the wear rates on the prostheses, however, the extent of increased wear and the impact on the longevity of the prosthesis is unclear. The NHS found that 45% of THA failures in 2019 were caused by wear which led to a multitude of failures such as infection, aseptic loosening and dislocation such that a revision surgery is then needed. In this study, a finite element model was created to model a walking cycle and a newly developed wear algorithm was used to perform a series of computational wear analyses to investigate the effect of different patient weights on the evolution of wear in THAs up to 5 million cycles. The wear rates shown in this study are closely comparable to previous literature. The XLPE volumetric wear rates were found to be between 15 and 35 mm3/yr (range: 1.5–57 .6mm3/yr) and femoral head taper surface volumetric wear rates were between 0.174 and 0.225 mm3/yr (range: 0.01–3.15 mm3/yr). The results also showed that an increased weight of 140 kg can increase the metallic wear by 26% and polyethylene wear by 30% when compared to 100 kg body weight. As increased wear can lead to a multitude of failure such as aseptic loosening, dislocation and metallosis, from this study, it is recommended that obese patients undergo recommended weight loss and maintain this lesser weight to reduce wear and prolong the life of the THA.

The mitigation of the risks of passenger injuries when a vehicle is involved in a collision with a street pole shielded with a layer of tire-derived material (TDM) was assessed. This can effectively absorb a fraction of the total energy from a speeding vehicle. Since such tests are expensive to conduct experimentally, the study relies on using the Abaqus/Explicit FEA solver to accurately calculate the non-linear nature of this scenario. Two categories of this scenario were evaluated to understand the effect a shielded street pole has on the vehicle—and the total absorbed energies during frontal and corner collisions, which are typically the most common categories of such accidents to happen. Results show that at lower speeds, these reinforcements are least effective in absorbing some of the kinetic energy applied by the vehicle, with about 5% of the energy absorbed by the reinforcement. At higher speeds, however, the results show that the TDM reinforcement absorbs about 28% of kinetic energy, which can reduce injury of the vehicle occupants, as well as decrease the damage on poles. Results for this simulation also show that there is a critical thickness of TDM that can absorb these kinetic energies, after which further thicknesses results in energies being applied back to the vehicle, therefore negating any purpose to further increase TDM thicknesses.

Three-dimensional (3D) printing, or additive manufacturing (AM), is a production can be utilised to fabricate 3D shapes from a simulated file. This technology has gained global popularity in the construction industry since 2014 due to its wide range of applications. AM promotes a more automated, innovative, flexible, and sustainable construction method, making it an integral part of the Construction Industry 4.0. However, there need to be more detailed studies regarding the effectiveness of AM as the future direction in the construction industry. This paper investigates the application of the finite element method (FEM) in assessing 3D-printed structures to get insight into the performance of these structures. Three leading 3D-printed structures were selected, including Dubai Future Foundation in the United Arab Emirates, Apis Cor house in Russia and PERI house in Germany. Structural and thermal analyses, including linear static, natural frequency, spectral response, and steady state heat, were performed using Strand7 to assess the effectiveness of AM in construction and the reliability of FEM in analysing 3D-printed structures. Although there are limited standards and regulations for 3D-printed structures in most countries, it was concluded that 3D-printed structures presented a similar strength to traditional ones. Moreover, FEM can be used to provide a reasonable analysis of the performance of these structures, while complying with the relevant standards. This paper presents a novel numerical procedure to assess the performance of small-scale 3D-printed structures under various mechanical and thermal loadings by checking against the relevant standards.

This study first provides an overview of the development of a novel tube anchor system for the seismic strengthening or repair of reinforced concrete (RC) shear walls with carbon fibre-reinforced polymer (CFRP) sheets. The new anchor system can significantly improve the load transfer mechanism between the CFRP and supporting RC structural elements, resulting in ductile behaviour of the strengthened shear walls with increases of lateral load capacity and ductility by up to 2.6 and 8.3 times, respectively. The study then presents a new finite element modelling technique capable of capturing the complete cyclic response, i.e., from the elastic behaviour to the ultimate collapse of CFRP-strengthened RC shear walls with the newly developed tube anchor system. Two different modelling approaches are proposed to consider the effects of the tube anchor system. Additionally, other important CFRP- and RC-related mechanisms, including CFRP debonding effects, confinement enhancement, tension stiffening, compression softening, and strength and stiffness degradation under cyclic loads, are also considered in the model. By comparing the analytical and experimental results, it is demonstrated that the proposed modelling approach can accurately replicate the complex behaviour of CFRP-strengthened shear walls with a wide range of aspect ratios, from the ductile flexural behaviour of slender walls to the brittle shear failure of squat walls, without requiring detailed modelling of the anchor system.

The structural safety of the infrastructure stock is an important issue in modern seismic performance assessments. Following recent seismic events, reports have highlighted the increased vulnerability of physical infrastructural assets, particularly for many bridges across the Italian road and motorway network. Italy possesses one of the most complex and intricate road systems in Europe which was constructed across irregular territories in terms of plan and elevation and of varying dimensions. As such, a comparative case study is presented herein. This case study aims to characterise the seismic vulnerability of the Vizzana-Zampogna viaduct which is part of the A15 Parma-La Spezia motorway, near the locality of Selva Bocchetto. The viaduct is considered representative of the 1970s construction period. It is approximately 342 m in length and is characterized by a flat curvilinear prestressed concrete deck consisting of 15 spans simply supported on reinforced concrete piers. To better understand the seismic structural response of the individual piers of the viaduct, a “multi-modal” nonlinear static analysis was developed, which allows the effects of sectional stresses relative to the variable load profiles of the single modes to be combined through the quadratic modal combination, and to be compared with the relevant limit state. The research aims to qualitatively identify the piers most vulnerable to seismic action and to study the effects that are induced by introducing variable loads and intensity scenarios of different earthquakes.

This paper deals with modelling strategies for the updating of Finite Element Models (FEMs) of infilled Reinforced Concrete (RC) frame buildings. As is known, this building typology is the most adopted worldwide for residential houses and strategic buildings, such as hospitals, schools, police stations, etc. The importance of achieving trustworthy numerical models for these kinds of structures, especially the latter ones, is clear. The updating procedure mainly consists in changing the geometrical and mechanical material properties of models until pre-determined convergence criteria are verified, the latter based on the comparison between numerical and experimental outcomes. In this work, the modelling strategies that can be adopted to refine FEMs of infilled RC buildings are treated in-depth, starting from the simple model usually developed for design purposes. Modelling techniques relevant to the geometry, the mechanical properties, the mass, and the restraint conditions of the model are discussed. Moreover, the approaches that can be adopted to calibrate numerical models during the construction process are addressed as well. Then, an application of the proposed strategies is provided with reference to a real building that was investigated during its construction. The proposed modelling strategies proved to be effective in the model updating of the considered building and provide useful support for the calibration of FEMs of this building typology in general.

The single point incremental forming (SPIF) process is a flexible and progressive manufacturing technique in the monolithic molding domain of heterogeneous metal pressing panels, which can contribute to the monolithic molding of metal pressing panels with complex contour and applicable to the fabrication of a small amount of titanium mesh plates for cranial prosthesis. A sandwich construction of titanium mesh was proposed in this paper for the purpose of inhibiting the indentation on the product surface and the deformation extent of mesh opening, as well as the forming accuracy of titanium mesh. The method of finite element modelling was applied to analyze the influence rules of low-melting-point alloy/synergistic deformation mechanism of titanium mesh as well as low-melting-point alloy layer on titanium mesh incremental forming quality. At last, the horizontal arrangement of significance regarding process parameters on sandwich titanium mesh wall thickness and rebound ratio effects was confirmed.

Rock bursts are a natural phenomenon that are caused by high stresses and faults within the deep geological profile. The framework within deep mining excavations, comprising various rock and face supports such as cable bolts, is required to withstand rock bursts. These mechanisms are subject to static and dynamic loading conditions which possess unique challenges. This study focused on the shearing impact of static loads on cable bolts, a key structural support mechanism designed to absorb energy and investigate the impacts of bolt diameter and strength. A double shear test was modelled using the Finite Element Analysis (FEA) software ABAQUS/Explicit. A double shear test was modelled using Finite Element Modelling (FEM) by creating individual parts, assigning material and contact properties and applying a load directly on the central block. Because ABAQUS/Explicit was used, a primarily dynamic analysis tool, quasi-static loading, was applied to negate the natural time scale. A total of six bolt diameters and six bolt strengths were tested. A positive correlation was exhibited between the bolt diameter, yield strength and the maximum force and displacement.

The early-age temperature rise in concrete, induced by cement hydration, poses a significant risk of thermal cracking. Accurate prediction of concrete hydration temperature is essential for thermal cracking prevention. Cement hydration heat obtained from isothermal calorimetry has been applied to concrete temperature modelling by previous studies. Isothermal calorimetry often excludes coarse aggregates due to the calorimeter capacity limitations, assuming mortar hydration heat can represent concrete, which may neglect the hydration delay effect of coarse aggregates. This study uses an isothermal calorimeter capable of accommodating coarse aggregates to measure the hydration heat of concrete and equivalent mortar, evaluating the validity of this assumption. Results show that the 3-day cumulative hydration heat of concrete exceeds that of mortar, especially at elevated curing temperatures. Significant differences were found in the activation energy and hydration parameters between concrete and mortar, indicating that the presence of coarse aggregates affects samples' temperature sensitivity and hydration heat development. Concrete temperature finite element modelling, validated by semi-adiabatic calorimetry, demonstrates that models based on concrete isothermal calorimetry data provide higher accuracy than those based on mortars. This study demonstrates that the hydration heat development, activation energy, and hydration parameters differ significantly between mortar and concrete. Concrete temperature models based on mortar hydration heat data can result in prediction errors exceeding 5 %. This study recommended employing micro-concrete samples in isothermal calorimetry to replicate actual concrete mixes., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

This study proposes a new, doubly re-entrant auxetic unit-cell design that is based on the widely used auxetic honeycomb structure. Our objective was to develop a structure that preserves and enhances the advantages of the auxetic honeycomb while eliminating all negative aspects. The doubly re-entrant geometry design aims to enhance the mechanical properties, while eliminating the buckling deformation characteristic of the re-entrant deformation mechanism. The effects of the geometric modification are described and evaluated using two parameters, offset and deg. A series of experiments were conducted on a wide range of parameters based on these two parameters. Specimens were printed via the vat photopolymerization process and were subjected to a compression test. Our aim was to investigate the mechanical properties (energy absorption and compressive force) and the deformation behaviour of these specimens in relation to the relevant parameters. The novel geometry achieved the intended properties, outperforming the original auxetic honeycomb structure. Increasing the offset and deg parameters results in increasing the energy absorption capability (up to 767%) and the maximum compressive force (up to 17 times). The right parameter choice eliminates buckling and results in continuous auxetic behaviour. Finally, the parameter dependency of the deformation behaviour was predicted by analytical approximation as well.

The process of lens shape change in the eye to alter focussing (accommodation) is still not fully understood. Modelling approaches have been used to complement experimental findings in order to determine how constituents in the accommodative process influence the shape change of the lens. An unexplored factor in modelling is the role of the modelling software on the results of simulated shape change. Finite element models were constructed in both Abaqus and Ansys software using biological parameters from measurements of shape and refractive index of two 35-year-old lenses. The effect of zonular insertion on simulated shape change was tested on both 35-year-old lens models and with both types of software. Comparative analysis of shape change, optical power, and stress distributions showed that lens shape and zonular insertion positions affect the results of simulated shape change and that Abaqus and Ansys show differences in their respective models. The effect of the software package used needs to be taken into account when constructing finite element models and deriving conclusions., (© 2024. The Author(s).)

Air pollution has been associated with several health problems. Detecting and measuring the concentration of harmful pollutants present in complex air mixtures has been a long-standing challenge, due to the intrinsic difficulty of distinguishing among these substances from interferent species and environmental conditions, both indoor and outdoor. Despite all efforts devoted by the scientific and industrial communities to tackling this challenge, the availability of suitable device technologies able to selectively discriminate these pollutants present in the air at minute, yet dangerous, concentrations and provide a quantitative measure of their concentrations is still an unmet need. Thermal conductivity detectors (TCDs) show promising characteristics that make them ideal gas sensing tools capable of recognising different gas analytes based on their physical fingerprint characteristics at the molecular level, such as their density, thermal conductivity, dynamic viscosity, and others. In this paper, the operation of TCD gas sensors is presented and explored using a finite element simulation of Joule heating in a sensing electrode placed in a gas volume. The results obtained show that the temperature, and hence, the resistance of the individual suspended microbridge sensor device, depends on the surrounding gas and its thermal conductivity, while the sensitivity and power consumption depend on the properties of the constitutive metal. Moreover, the electrode resistance is proven to be linearly dependent on the applied voltage.

Background: Endoscopic strip craniectomy followed by helmet therapy (ESCH) is a minimally invasive approach for correcting sagittal craniosynostosis. The treatment involves a patient-specific helmet designed to facilitate lateral growth while constraining sagittal expansion. In this study, finite element modelling was used to predict post-treatment head reshaping, improving our comprehension of the necessary helmet therapy duration., Method: Six patients (aged 11 weeks to 9 months) who underwent ESCH at Connecticut Children's Hospital were enrolled in this study. Day-1 post-operative 3D scans were used to create skin, skull, and intracranial volume models. Patient-specific helmet models, incorporating areas for growth, were designed based on post-operative imaging. Brain growth was simulated through thermal expansion, and treatments were modelled according to post-operative Imaging available. Mechanical testing and finite element modelling were combined to determine patient-specific mechanical properties from bone samples collected from surgery. Validation compared simulated end-of-treatment skin surfaces with optical scans in terms of shape matching and cranial index estimation., Results: Comparison between the simulated post-treatment head shape and optical scans showed that on average 97.3 ± 2.1 % of surface data points were within a distance range of -3 to 3 mm. The cranial index was also accurately predicted (r = 0.91)., Conclusions: In conclusion, finite element models effectively predicted the ESCH cranial remodeling outcomes up to 8 months postoperatively. This computational tool offers valuable insights to guide and refine helmet treatment duration. This study also incorporated patient-specific material properties, enhancing the accuracy of the modeling approach., Competing Interests: Declaration of competing interest None to declare., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

While much has been done to study how cartilage responds to mechanical loading, as well as modelling such responses, arguably less has been accomplished around the mechanics of the cartilage–bone junction. Previously, it has been reported that the presence of bony spicules invading the zone of calcified cartilage, preceded the formation of new subchondral bone and the advancing of the cement line (Thambyah and Broom in Osteoarthr Cartil 17:456–463, 2009). In this study, the morphology and frequency of bone spicules in the cartilage–bone interface of osteochondral beams subjected to three-point bending were modelled, and the results are discussed within the context of biomechanical theories on bone formation. It was found that the stress and strain magnitudes, and their distribution were sensitive to the presence and number of spicules. Spicule numbers and shape were shown to affect the strain energy density (SED) distribution in the areas of the cement line adjacent to spicules. Stresses, strains and SED analyses thus provided evidence that the mechanical environment with the addition of spicules promotes bone formation in the cartilage–bone junction. [ABSTRACT FROM AUTHOR]

• Mechanical stability plays a key role in the effectiveness of external fixators. • Strength and stiffness are the main factors which contributes towards stability. • Modified configurations of linear, circular and hybrid fixators are investigated. • Light weight composite materials are gradually replacing traditional metallic alloys. • Existing research gaps in further optimizing external fixators are identified. External Fixators are a common technique used to treat a variety of issues related to bones, predominantly due to its non-intrusive nature and versatility in terms of form and materials. While it is mainly used to treat open fractures, its other uses include limb lengthening, deformity correction, bone grafting, compression of non-unions and stabilization of dislocations. Its earliest use dates as far back as 400 BCE and has undergone significant improvements, focusing on both customization and optimization. These two aspects highlight the significance of complementing the orthopaedic requirements with engineering knowledge and its applications. Hence, this review paper aims to conduct an examination of recent developments of external fixators with a special focus on its structure, the usage of materials and biomechanical investigations using experimental and numerical techniques. The paper presents the existing level of engineering knowledge with regards to these aspects and identifies research gaps, which can improve the quality of the commonly used external fixators. [ABSTRACT FROM AUTHOR]

Ultra-Thin Continuously Reinforced Concrete Pavement (UTCRCP) consists of a 50 mm thin High-Strength Steel-Fibre-Reinforced Concrete (HS-SFRC) overlay placed on existing pavements as rehabilitation or used as part of new pavements. Difficulties have been experienced with the construction of UTCRCP. Additionally, the thin HS-SFRC has superior fatigue properties, but poor load-spreading ability compared to conventional concrete pavements due to its reduced thickness. This results in high deflections when the pavement is loaded. The substructure of UTCRCP plays an important role in its performance. Cement-stabilised granular materials can be used to ensure gradual load spreading with depth, but its behaviour under flexible concrete layers is not yet well understood. In this study the effect of increasing the HS-SFRC layer thickness and the effect of incorporating cement-stabilised base layers were investigated using linear elastic finite element modelling. From stress levels calculated, it was found that C1 and C2 materials perform well underneath a 50 mm HS-SFRC layer subjected to standard axle loads of 80 kN, while C3 and C4 would deteriorate faster. Stabilised layers placed below a thin, flexible concrete layer may however crack, resulting in increased damage to supporting layers. It is recommended that the response of UTCRCP should be investigated using advanced material models for the cement-stabilised base and other substructure layers. [ABSTRACT FROM AUTHOR]

To verify the effectiveness of polyurethane cement-prestressed steel wire ropes for flexural reinforcement of reinforced concrete T-girders, this paper conducts flexural test research on 7 pieces of T-girder specimens. Through the ABAQUS finite element program to build a model for numerical simulation, the results show polyurethane cement prestressed steel wire rope reinforcement can significantly increase the yield load and ultimate load of reinforced girders. Taking a girder in the test (20mm reinforcement thickness of polyurethane cement) as an example, yield load and ultimate load increased by 61.5% and 102.3% compared to unreinforced girder. The finite element model calculation results of T-girder bending reinforcement are in good agreement with the bending reinforcement test, and the error is only about 2%. For different strength concrete, the yield load increases slightly with the increase of concrete strength. For T-girders with different reinforcement ratios, the bearing capacity of strengthened girders changes significantly with the increase of longitudinal reinforcement ratio. The yield load of girders with reinforcement ratio of 1.82% and 1.35% is 29.84% and 65.85% higher than that of girders with reinforcement ratio of 0.91%. The yield deflection is 13.18% and 3.99% higher than that of girders with reinforcement ratio of 0.91%. It can be concluded that the bending reinforcement method of polyurethane cement prestressed steel wire ropes can effectively strengthen the main girder and ensure the structural safety. [ABSTRACT FROM AUTHOR]

Driven by the exceptionally high mechanical properties of carbon nanotubes (CNTs), over the years an extensive research effort has been devoted to the reinforcement of high-performance polymer fibres with CNTs. However, to date, improvements in the strength of these fibres have been rather modest even for relatively high CNT contents. After a brief review of CNT reinforced polymer fibres, here, analytical and numerical finite element models will be used to show that these experimental findings are to be expected based on the intrinsic mechanical properties of these polymer fibres and CNTs, their aspect ratio and interfacial characteristics. Results show that for realistic CNT contents and aspect ratios, the extraordinary strength of CNTs cannot be easily fully exploited in high-performance polymer fibres like Dyneema®or Kevlar®. Even if CNTs are perfectly aligned, bonded and dispersed, the low intrinsic shear strength of these highly anisotropic polymer fibres limits effective stress transfer and nanotube reinforcement. [ABSTRACT FROM AUTHOR]

Slim floor systems are very common nowadays and various types are currently being used for the construction of high-rise buildings and car parks. Concrete in slim floor beams encases the steel beam section which helps to improve their fire resistance. Despite their higher fire resistance, several fire protection materials like intumescent coatings are often used to achieve a higher fire resistance where desired. The thermal properties and behaviour of various intumescent coating materials were previously studied through experimental investigations. This paper presents finite element analyses to simulate the response of unprotected and protected slim floor beams in fire using different simulation tools. For this purpose, fire tests conducted on unprotected slim floor beams and intumescent coating materials are modelled using research and commercial software. Results from the analyses are compared and verified with the available test data. These validated models are later combined to study the behaviour of protected slim floor beams in fire. Results from the study show that the research and the commercial software replicate the behaviour of slim floor beams and protection materials with good accuracy. Due to the presence of the intumescent coating, the protected slim floor beams displayed a better fire resistance as the temperature of the steel part remained below 400 °C even after 60-min of standard heating. The protected slim floor beams continued to support the external loads even after 120 min of heating. [ABSTRACT FROM AUTHOR]

This article presents the latest of a series of research activities aimed to determine the deviation originated when Prescale pressure measurement film is used to measure the size and shape of the wheel-rail contact area. Despite being an attractive solution due to the simplicity of the measurement procedure, it is well known that the contact interaction is altered by the presence of the film. Consequently, characterizing and filtering out the systematic measurement error is a fundamental requirement for accurate quantitative assessments. Nevertheless, the complexity of the wheel-rail contact problem, which lacks an analytical solution, hinders the direct determination of correction values. The approach presented here builds on error corrections for simpler Hertzian geometries to calibrate a film model for further use in the wheel-rail contact scenario. The results highlight the marked dependency of the measurement error on wheel and rail roughness and underline the importance of including the film into finite element models that are validated by comparison with experimental observations. [ABSTRACT FROM AUTHOR]

Innovative materials such as Engineered Cementitious Composite (ECC) with inherent crack control and corrosion resistant Glass Fibre-Reinforced Polymer (GFRP) bars are studied for implementation in joint-free bridges with link slab. The GFRP-reinforced ECC link slab is tested experimentally under static monotonic loading and structural performance is compared with its steel-reinforced counterpart. Finite element (FE) models for steel-/GFRP-reinforced link slab are developed taking into consideration of ECC and GFRP material properties and their performance validated based on experimental results. FE models are found to simulate the behaviour of link slabs reasonably well (in terms of predicting load-deformation response, maximum/peak load capacity, concrete or steel/GFRP bar strain development, concrete cracking and failure modes) as the experimental and FE predicted results/response are found to be in good agreement. FE model is then used to conduct a parametric study for the optimization of GFRP-reinforced ECC link slabs design parameters (such as GFRP/ECC modulus of elasticity, GFRP rupture strength, ECC compressive/flexural strength/maximum sand grain size and link slab reinforcement ratio) to study their influence on structural performance. GFRP-reinforced link slab shows higher load and deflection/ductility capacity compared to their steel-reinforced counterparts. Developed FE models are found to reasonably predict load capacity of ECC link slabs within 90% to 97% (for GFFRP reinforced) and 82% to 92% (for steel reinforced) of the experimental values. Both GFRP- and steel-reinforced link slabs exhibited their potential for the construction of joint-free bridges and develop FE models can be used as tools for the optimization of design variables. [ABSTRACT FROM AUTHOR]

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Three-dimensional (3D) printing with biocompatible resins offers new competition to its opposition—subtractive manufacturing, which currently dominates in dentistry. Removing dental material layer-by-layer with lathes, mills or grinders faces its limits when it comes to the fabrication of detailed complex structures. The aim of this original research was to design, materialize and clinically evaluate a functional and resilient shape of the orthodontic power-arm by means of biocompatible 3D printing. To improve power-arm resiliency, we have employed finite element modelling and analyzed stress distribution to improve the original design of the power-arm. After 3D printing, we have also evaluated both designs clinically. This multidisciplinary approach is described in this paper as a feasible workflow that might inspire application other individualized biomechanical appliances in orthodontics. The design is a biocompatible power-arm, a miniature device bonded to a tooth surface, translating significant bio-mechanical force vectors to move a tooth in the bone. Its design must be also resilient and fully individualized to patient oral anatomy. Clinical evaluation of the debonding rate in 50 randomized clinical applications for each power-arm-variant showed significantly less debonding incidents in the improved power-arm design (two failures = 4%) than in the original variant (nine failures = 18%). [ABSTRACT FROM AUTHOR]

Scoliosis is a deformity of the spine that in severe cases requires surgical treatment. There is still disagreement among clinicians as to what the aim of such treatment is as well as the optimal surgical technique. Numerical models can aid clinical decision‐making by estimating the outcome of a given surgical intervention. This paper provided some background information on the modelling of the healthy spine and a review of the literature on scoliotic spine models, their validation, and their application. An overview of the methods and techniques used to construct scoliotic finite element and multibody models was given as well as the boundary conditions used in the simulations. The current limitations of the models were discussed as well as how such limitations are addressed in non‐scoliotic spine models. Finally, future directions for the numerical modelling of scoliosis were addressed. [ABSTRACT FROM AUTHOR]

All around the world, non-engineered masonry constructions (NECs) typically have high vulnerability to seismic ground motion, resulting in heavy damage and severe casualties after earthquakes. Even though a number of computational strategies have been developed for seismic analysis of unreinforced masonry structures, a few studies have focussed on NECs located in developing countries. In this paper, different modelling options for finite element analysis of non-engineered masonry buildings are investigated. The goal of the study was to identify the modelling option with the best trade-off between computational burden and accuracy of results, in view of seismic risk assessment of NECs at regional scale. Based on the experimental behaviour of a single-storey structure representative of Indian non-engineered masonry buildings, the output of seismic response analysis of refined 3D models in ANSYS was compared to that of a simplified model based on 2D, nonlinear, layered shell elements in SAP2000. The numerical-experimental comparison was carried out under incremental static lateral loading, whereas nonlinear time history analysis was performed to investigate the dynamic performance of the case-study structure. Analysis results show that the simplified model can be a computationally efficient modelling option for both nonlinear static and dynamic analyses, particularly in case of force-based approaches for design and assessment of base isolation systems aimed at the large-scale seismic vulnerability mitigation of NECs. [ABSTRACT FROM AUTHOR]