In this study, nonlinear vibrations of a slightly curved Timoshenko beam with nonlinear boundary conditions are investigated. The formulation is developed based on Timoshenko beam theory, incorporating shear deformation and rotary inertia effects. Geometric nonlinearity is introduced through the von Karman strain–displacement relations, and the governing equations of motion are derived using Hamilton’s principle. The resulting partial differential equations are reduced to a set of ordinary differential equations via the Galerkin method, where the mode shapes of a linear straight Timoshenko beam with linear spring boundary conditions are employed as admissible functions. The temporal response of the system is obtained using the method of multiple scales. Validation of the proposed formulation is carried out by examining the limiting case of vanishing curvature and by comparison with the nonlinear response of straight Timoshenko beams and thick shallow arch models. The results reveal that both hardening and softening behaviors may occur due to the presence of second- and third-order nonlinear terms. The proposed semi-analytical framework provides an efficient tool for analyzing nonlinear vibrations of slightly curved Timoshenko beams, capturing the combined effects of geometric nonlinearity, shear deformation, rotary inertia, and boundary flexibility.

This study presents a series of novel mirrored multi-cell square tubes (NMST) developed through the application of various evolutionary designs and mirror settings to traditional multi-cell square tubes. Numerical simulations were performed using validated models to assess their crashworthiness under conditions of uniform wall thickness and mass. The findings indicate that the implementation of mirror settings significantly enhances the crashworthiness of the structure, with strategy E demonstrating a particularly marked improvement. Under conditions of equal wall thickness, NMSTE4 exhibited increases in specific energy absorption (SEA) and crush force efficiency (CFE) of 47.15% and 24.15%, respectively, when compared to NMSTE1. Under equal mass conditions, these values increased by 24.84% and 25.53%, respectively. Parametric studies revealed that both an increase in wall thickness and the incorporation of additional mirror settings contribute positively to the energy absorption performance of the structure. The integration of the design characterized by strategy D with those of other strategies further enhances the impact resistance of the original structure, with the AD combination yielding the most substantial improvement. Specifically, compared to NMSTA4, NMSTAD demonstrated increases in energy absorption (EA), SEA, and CFE of 43.85%, 21.91%, and 13.20%, respectively. A comparative analysis was conducted, revealing that compared to non-mirrored design structures, NMSTD4 achieved SEA and CFE improvements of up to 106.38% and 32.43%, respectively.

An efficient structural model combines an economic structural form with advanced, efficient material. The curved toroidal shells are aesthetically appealing, stiff structures that are preferred to cover long spans of stadiums, auditoriums, museums, and airports. Since the second half of the last century, laminated composites gained popularity among practicing civil engineers owing to the high strength-to-weight ratio, flexibility to orient the major load-carrying capacity along the directions of governing stresses, and superior fatigue resistance. The research in the field of laminated composite shells is quite vast. However, the same effort on the composite toroidal shells are relatively scanty. Hence this paper aims to address that gap in the literature to popularise the use of composite toroidal shells further among practicing engineers. A C0 continuous, isoparametric, geometrically non-linear finite element code is proposed here which combines Reissner-Mindlin theory and Sander’s non-linear shell theory applicable to moderately thin panels. The governing equation is derived by minimising the total potential energy with respect to the shell deformations and solved using the Newton-Raphson method. The results are so presented that practically viable design guidelines can be recommended for practical use.

Design optimisation in structural engineering plays a crucial role in improving the performance structures by minimising material usage and reducing costs. However, shape and topology optimisation of structures undergoing large deformations presents significant challenges, due to its inherent non-linearity. This work presents an advanced isogeometric gradient-based shape optimisation framework tailored for geometrically non-linear beams, by carrying out the design sensitivity analysis within a curvilinear coordinate system, derived from non-uniform rational B-splines (NURBS) space. This enables non-parametric shape optimisation of beam structures, directly integrating computer-aided design (CAD), finite element modelling (FEM), and an optimisation strategy that combines non-linear path-following methods with iterative design modifications. As an initial step, a 1D isogeometric finite element framework accounting for geometrical non-linearities is developed. Using the isogeometric analysis several benchmark problems accounting of beam undergoing large deformations is solved and validated against analytical results. This framework is integrated with a gradient-based optimisation scheme by employing the adjoint sensitivity method, particularly crucial in scenarios where the number of design variables exceeds the number of constraint equations. We consider objective function of the optimisation as “minimising strain energy”, with the B-spline mesh control points serving as the design variables. The interior point method was employed due to its efficiency in handling non-linear optimisation problems. This developed methodology demonstrates the potential of isogeometric shape optimisation as a powerful tool for improving the performance and efficiency of geometrically non-linear beam structures in diverse engineering applications.

Buckling and post-buckling behaviour of functionally graded carbon nanotube reinforced composite (FG-CNTRC) plate under in-plane triangular loading is presented in this article by finite element method (FEM). Present investigation includes uniform distribution (UD), FG-X and FG-A distribution of carbon nanotubes (CNTs) within plate thickness. Extended rule of mixture is adopted to compute net mechanical properties. Plate element is modelled by 8-noded degenerated shell element using FSDT and isoparametric formulation. Buckling and post-buckling analyses are performed by solving eigenvalue equation and non-linear equilibrium equation. To ensure accuracy of formulation, obtained results are verified with previous results. Later focused on effect of volume fraction, distribution of CNTs, and various triangular loads on post-buckling behaviour.

Seismic response analysis of soil-fault-tunnel (SFT) systems involves numerical simulations that consider factors such as seismic sources, wave propagation paths, local site effects, and the spatial variation of soil properties. Past earthquakes, especially the 2008 Wenchuan (China) and 2011 Tohoku (Japan) events, have shown the vulnerability of tunnels. Traditional fault rupture models require simulating large areas, which is computationally intensive. This paper employs an efficient modelling technique known as the domain reduction method (DRM) to analyse the seismic response of SFT systems. The DRM works in two steps: first, calculating the nodal effective forces from fault rupture (free-field analysis), and then, limiting the analysis to a smaller domain that includes the tunnel, with an artificial boundary layer that uses the nodal forces from the first step. Monte Carlo simulations were performed to understand the overall response of the tunnel, considering the shear wave velocity (Vs) as a spatially varying random variable in the model. The study examined a circular tunnel cross-section subjected to inclined earthquake faults using a three-layer DRM approach, with 210 realisations for stochastic dynamic analysis of the SFT system. Numerical simulations were performed using Multi-hazard Analysis for STOchastic time-DOmaiN phenomena (MASTODON), based on the multi-physics object-oriented simulation environment (MOOSE) framework. The results show how fault inclination affects the tunnel, the generation of surface waves, and local site effects such as frequency shifts and the amplification or attenuation of seismic waves caused by the tunnel. These findings are useful for designing tunnels more efficiently and reliably, as well as developing engineered materials to reduce seismic wave impacts on critical infrastructure.

The peridynamics models are capable of capturing long-range interactions as well as the damage growth processes that most of the other local approaches are unable to account. This study examines whether the bond-based peridynamics (BB-PD) model can account for the presence of initial damage and studies its effect on further crack growth. A plate with a circular hole at its centre, which is under the action of quasi-static loading along its horizontal edges, is considered as an example problem. The creation of such a hole can lead to damage around it. The current study proposes a simple method to introduce initial damage by reducing the bond stiffness. The reduction is applied to the bonds between particles within their respective horizons for a small region around the hole. For the present study, the initial damage is considered uniform. The results indicate that the existence of damage and its subsequent growth contribute to crack propagation and elevated damage levels near the hole. The study proves that initial damage can be incorporated into the BB-PD model using the proposed method, and it can successfully simulate further progress of the damage.

This paper presents a comprehensive study on the modelling and optimisation of a piezoelectric sandwich energy harvester featuring auxetic cores compared to isotropic cores, aimed at enhancing vibrational energy harvesting efficiency. The proposed auxetic piezoelectric energy harvester with a tapered thickness is engineered to achieve a more uniform stress distribution, leading to significant improvements in power output and energy density compared to conventional uniform-thickness designs. Through finite element analysis (FEA) and experimental validation, the optimised TAEH demonstrates enhanced electromechanical performance. Additionally, a numerical model is developed to simulate the dynamic behaviour of the energy harvester with auxetic substrates. Simulations reveal that the auxetic core induces biaxial strain in the piezoelectric material, generating higher electrical output without increasing mechanical stress. The model is refined through iterative simulations to accurately predict the harvester’s structural and electrical performance, showcasing the potential of auxetic designs to advance the field of sustainable vibrational energy harvesting in mechanical systems.

The development of light weight biodegradable hybrid nanofillers and hybrid natural fibre laminates constitute a major step forward in the field of sustainable materials research. This study focuses towards hybrid nanofillers made of graphene nanoplatelets and multi-walled carbon nanotubes in combined proportion of 3 wt.% is added in hybrid natural fibre (NF) of bamboo fibre (BF) and kenaf fibre (KF) stacked in the sequence of BFO+KFO+BFO+KFO+BFO (BKF1), BF9O+KFO+BF9O+KFO+BF90 (BKF2), BFO+KF9O+BFO+KF90+BFO (BKF3), and BF9O+KF9O+BF90+KF90+BF90 (BKF4) using vacuum infusion technique, followed by compression moulding. The biodegradable polymer designated as poly-lactic acid (PLA) served as matrix and the mechanical testing were performed on manufactured specimens viz., tensile strength, % elongation, shore D hardness, impact, interlaminar shear, and flexural strength, and thermo-mechanical testing in accordance with ASTM recommendations. The results show that aligning the fibres seems to make the laminates’ thermo-mechanical and mechanical properties better. The BKF3 sample beats the other laminates because it is more stable in heat and has better mechanical properties.

Dependable, contemporaneous sensor systems that can relyably operate despite motion artifacts, noise, and limited power resources are necessary for continuous heart health monitoring. We describe a multimodal technique to monitoring cardiovascular data using earable sensor devices in this paper. To enable self-powered detection of heart vibrations (PCG/PPG-derived waveforms), the suggested wearable employs piezoelectric materials to collect biomechanical energy from human motion. By enhancing high-fidelity cardiac waveforms using a Generative Adversarial Network (GAN) while maintaining morphological properties, medical datasets that are sparse or unbalanced may be addressed. A prediction model based on Kalman Filters is used to monitor cardiac states such heart rate variability (HRV), systolic timing intervals (STI), and probable arrhythmic patterns. This allows for real-time state estimates and noise suppression. The introduction of a lightweight consortium blockchain infrastructure guarantees safe multi-node access, data integrity, and provenance. Remote cardiac telemedicine is a good fit for this paradigm because it offers tamper-resistant medical records, patient identity security, decentralized verification, and visible audit trails. The combined GAN-Kalman architecture decreases noise by 30–45%, increases cardiac anomaly classification accuracy by 12–18%, and shortens real-time prediction latency, according to experimental simulations.