Sondipon Adhikari

University of Glasgow | UofG · James Watt School of Engineering

Microcantilevers are widely employed in sensing applications because they are highly sensitive to changes in vibrational frequency. The Q-factor, a measure of the effectiveness of energy storage in resonant systems, is a crucial parameter that directly influences the sensitivity and performance of microcantilevers. Conventional approaches to improv...

Vibration energy harvesting is a technology that enables electric power generation by augmenting vibrating materials or structures with piezoelectric elements. In a recent work, we quantified the intrinsic energy-harvesting availability (EHA) of a piezoelectric phononic crystal (Piezo-PnC) by calculating its damping ratio across the Brillouin zone...

Tacticity is long known as a significant contributor in changing the chemical and mechanical properties of the polymers drastically. This study explores mechanism of bandgap formation in elastic mechanical metastructures designed with a focus on tacticity. We introduce metabeams, comprising a primary slender beam embedded with short secondary beams...

Reliability analysis of highly sensitive structures is crucial to prevent catastrophic failures and ensure safety. Therefore, these safety-critical systems are to be designed for extremely rare failure events. Accurate statistical quantification of these events associated with a very low probability of occurrence requires millions of evalu­ations o...

In this work, we illustrate the implementation of physics informed neural networks (PINNs) for solving forward and inverse problems in structural vibration. Physics informed deep learning has lately proven to be a powerful tool for the solution and data-driven discovery of physical systems governed by differential equations. In spite of the popular...

The article introduces the nonlinear negative stiffness base isolators (NNBI). These isolators are used to reduce the dynamic responses of single degrees of freedom systems (SDOF). Lagrange’s equation is applied to derive the nonlinear governing equations of motion of the isolated SDOF system. The statistical linearization method is applied to line...

In order to lessen the dynamic reactions of liquid storage tanks, the nonlinear inertial amplifier friction bearings are introduced in this paper. The liquid storage tanks’ governing equations of motion are obtained by applying Newton’s second law. The governing equations of motion of isolated structures are linearized for each nonlinear component...

This paper explores the emergence of topological interface states in one-dimensional locally resonant lattices incorporating inerters in both nearest neighbor (NN) and beyond-nearest neighbor (BNN) coupling. The investigation focuses on the unique wave propagation characteristics of these lattices, particularly the presence and behavior of interfac...

Resonators, inertial amplifiers, negative stiffness devices, and impacting oscillators are added to the core materials of conventional passive vibration isolation systems to address their shortcomings. In order to manage the vibration of dynamic systems with a single or multiple degrees of freedom, unique linear and nonlinear passive vibration isol...

The unit cells connected periodically at a single node with only one degree of freedom is called a monocoupled system. Dispersion relations for such systems are studied widely; however, the analytical solution for salient features of the attenuation band, such as the number of peaks in a band and band merging, have been relatively unexplored. In th...

Traditionally lattice materials are made of a network of beams in two and three dimensions with majority of the lattice volume being void space. Recently researchers have started exploring ways to exploit this void space for multi-physical property modulation of lattices such as global mechanical behaviour including different elastic moduli, wave p...

The increasing significance of digital twin technology across engineering and industrial domains, such as aerospace, infrastructure, and automotive, is undeniable. However, the lack of detailed application-specific information poses challenges to its seamless implementation in practical systems. Data-driven models play a crucial role in digital twi...

The combination of negative stiffness devices and inerters to traditional base isolators (TBI) and tuned mass dampers (TMD) does not exist in any state-of-the-art. Therefore, to pursue the research using the above-mentioned research scope, the negative stiffness inerter passive dampers such as negative stiffness inerter-based base isolators (NSIBI)...

The additional inerter-based viscoelastic mass dampers (AIVMD) and additional viscoelastic mass damper inerters (AVMDI) are introduced in this article. H2 and H∞ optimization schemes are utilized to derive the optimal closed-form solutions for these novel dampers analytically. A parametric study performs to investigate the sensitivity of the optima...

A partitioned/combined computational method based on Newmark scheme is proposed to analyze dynamic systems with different temporal scales and element scales. To effectively filter spurious high-frequency vibration content and retain the second-order accuracy simultaneously, Generalized-α schemes are investigated and incorporated into the proposed m...

The inertial amplifier viscoelastic base isolators (IAVBI) are introduced in this paper. The viscoelastic materials are implanted inside the core material of the inertial amplifier base isolators. The standard linear solid (SLS) models are applied to formulate the viscoelastic material mathematically. The viscoelastic materials are also implanted i...

This paper introduces the inertial amplifier viscoelastic tuned mass dampers (IAVTMD). The viscoelastic materials are implanted inside the core material of the inertial amplifier tuned mass dampers. The standard linear solid models are applied mathematically to formulate the viscoelastic material. H 2 and H ∞ optimization mechanisms apply to derive...

The negative stiffness inerter-based base isolators (NSIBI) are introduced in this paper. The negative stiffness device and inerters are installed inside the core of the conventional base isolators (CBI) to enhance their dynamic response reduction capacity. The novel isolators have been installed at the multi-storey building's base to mitigate thei...

The prediction of the design parameters of short to medium-span supported bridges in critical locations (such as canal/road crossings) under the action of high-speed trains has been investigated in this article. An artificial neural network (ANN)-based MIMO (multiple-input multiple-output) metamodels is proposed in conjunction with the semi-analyti...

Inerter-based periodic structures have attracted significant interest among the research community due to their wide range of applications. However, existing studies on quasiperiodic structures, especially with inerters, are limited. Therefore, this timely work investigates the dynamics of novel one-dimensional inerter-based quasiperiodic lattices...

A framework for creating and updating digital twins for dynamical systems from a library of physics-based functions is proposed. The sparse Bayesian machine learning is used to update and derive an interpretable expression for the digital twin. Two approaches for updating the digital twin are proposed. The first approach makes use of both the input...

In-plane wave propagation in hexagonal and re-entrant lattices is a widely investigated subject in the literature. Such systems can exhibit many different but limited band structure properties that depend on the topology and geometry of structural members and the lattice itself. This manuscript proposes a novel class of hexagonal and re-entrant lat...

Non-reciprocal wave propagation in acoustic and elastic media has received much attention of researchers in recent years. This phenomenon can be achieved by breaking the reciprocity through space- and/or time-dependent constitutive material properties, which is an important step in overcoming the limitations of conventional acoustic- and phononic-l...

The optimum inertial amplifier tuned mass dampers (IATMD) for vibration reduction of linear and nonlinear dynamic systems are introduced in this paper. [Formula: see text] and [Formula: see text] optimization methods are applied to derive the exact closed-form expressions for optimal design parameters such as frequency and viscous damping ratios in...

This article demonstrates the possibility of energy harvesting by mistuned pendulums with torsional coupling. Two pendulums of different lengths with coils and magnets at the pivots are used as electromagnetic harvesters. The ambient energy source to the system is considered in the form of harmonic base excitations. Torsional coupling is achieved b...

Wave propagation characteristics of an elastic bar coupled at one end with a single degree of freedom, bi-stable, essentially nonlinear snap-through element are considered. The free end of the bar is subjected to sinusoidal excitations. A novel approach based on multiple time scales and harmonic balance method has been proposed to analytically inve...

2D lattices are widely popular in micro-architected metamaterial design as they are easy to manufacture and provide lightweight multifunctional properties. The mechanical properties of such lattice structures are predominantly an intrinsic geometric function of the microstructural topology, which are generally referred to as passive metamaterials s...

The negative stiffness inertial amplifier tuned mass dampers (NSIA-TMD) are introduced in this paper. Another two novel tuned mass dampers such as negative stiffness tuned mass damper (NS-TMD) and inertial amplifier tuned mass damper (IA-TMD) are mathematically developed from the negative stiffness inertial amplifier tuned mass dampers (NSIA-TMD) a...

The optimal design of inertial amplifier base isolators (IABI) for dynamic response mitigation of multi-storey buildings subjected to base excitations has been studied in this paper. In order to achieve the closed-form expressions for optimal design parameters of IABI, H2 optimization method has been employed. The effectiveness of the closed-form e...

This paper proposes an analytical stochastic spectral dynamic stiffness method (SSDSM) for free and forced vibration analysis of plate built-up structures subject to uncertain viscoelastic boundary or connection conditions (BCs or CCs). First, a recently developed spectral dynamic stiffness (SDS) theory for broadband vibration analysis of plate bui...

The unit cells connected periodically at a single node with only one degree of freedom is called a monocoupled system. Dispersion relations for such systems are studied widely; however, the analytical solution for salient features of the attenuation band, such as the number of peaks in a band and band merging, have been relatively unexplored. In th...

Wave dispersion and topology of phononic crystals in classical mechanical systems are well understood and extensively studied subjects. However, the topological properties of acoustic metamaterials with more complex unit cells having several masses, internal resonators, and inerter elements is an insufficiently investigated topic. In this work, we...

Uncertainties arising in the parameters and modelling of complex systems need to be considered for credible predictions of their dynamic response. For most practical systems, the detailed information regarding these two types of uncertainties is not available. In this paper, the Wishart random matrix model is presented to quantify the total uncerta...

Physics-informed neural networks have received considerable attention for the solution and data-driven discovery of physical systems governed by differential equations. Despite their immense success, it has been observed that the first-generation PINNs suffer from a drawback arising from the regularization of the loss function. The motivation of th...

Lattice structures with Plateau borders (LSPB) have attracted increasing interests recently due to the improved stiffness, strength, energy absorption properties. Undoubtedly, vertexes with Plateau borders (VPB) play a significant role on the dynamic elastic moduli. This paper proposes an analytical framework of the frequency-dependent equivalent i...

Metadamping is the phenomenon of either enhanced or diminished intrinsic dissipation in a material stemming from the material's internal structural dynamics. It has previously been shown that a locally resonant elastic metamaterial may be designed to exhibit higher or lower dissipation compared to a statically equivalent phononic crystal with the s...

This paper proposes two significant developments of the Wittrick–Williams (W–W) algorithm for an exact wave propagation analysis of lattice structures based on analytical dynamic stiffness (DS) model for each unit cell of the structures. Based on Bloch’s theorem, the combination of both the DS and the W–W algorithm makes the wave propagation analys...

Stiffness matrices of beams with stochastic distributed parameters modelled by random fields are considered. In stochastic finite element analysis, deterministic shape functions are traditionally employed to derive stiffness matrices using the variational principle. Such matrices are not exact because the deterministic shape functions are not deriv...

The closed-form analytical expression of the objective function of a single degree of freedom system with the tuned mass damper, subjected to Gaussian white noise and Kaimal forcing spectrum, is derived implementing the H 2 optimization technique. To illustrate the procedure, a wind turbine tower with and without the tuned mass damper, subjected to...

This study reports the presence of an interface mode in the one-dimensional topologically arranged mechanical metamaterials using mechanical dome shaped metastructures which can be exhibited by hourglass configurations. The paper proposes the method of obtaining a localized interface mode within the bandgap using the hourglass shaped resonating ele...

2-D lattice structures have gained significant attention in the last few decades. Extensive analytical and experimental studies have been conducted to determine the elastic properties of the lattice structures. Further, the variation in the elastic properties of the passive lattice structures by changing various dimensional parameters and geometry...

Wave propagation characteristics of an elastic bar coupled at one end with a single degree of freedom, bi-stable, essentially nonlinear snap-through element are considered. The free end of the bar is subjected to sinusoidal excitations. A novel approach based on Multiple Time Scales and Harmonic Balance Method has been proposed to analytically inve...

Background The architected mechanical metastructures have garnered significant research attention for various engineering applications due to their remarkable mechanical properties and unique deformation behavior. The lattice-based micro-structured materials have shown enhanced mechanical properties and the ability to control wave propagation, maki...

We theoretically investigate the bandgap formation in an Euler–Bernoulli beam-based metastructure with periodically attached double negative 3-dof local resonators. The idiosyncratic physical phenomena found in mechanical metamaterials, such as negative stiffness and mass, are introduced in the attached local resonator to design the double negative...

This paper proposes an efficient and reliable eigenvalue solution technique for analytical stochastic dynamic stiffness (SDS) formulations of beam built-up structures with parametric uncertainties. The SDS formulations are developed based on frequency-dependent shape functions in conjunction with both random-variable and random-field structural par...

Offshore structures are exposed to cyclic loading and thereby at risk of fatigue failure, especially at the welded joints between trusses in offshore jacket foundations. In this paper, an optimization framework for welded joints considering fatigue damages is presented. The framework can be used to optimize the orientation and location of welds con...

Uncertainties need to be taken into account in the dynamic analysis of complex structures. This is because in some cases uncertainties can have a significant impact on the dynamic response and ignoring it can lead to unsafe design. For complex systems with uncertainties, the dynamic response is characterised by the eigenvalues and eigenvectors of t...

Carbon-based nanostructures are receiving increasing attention over the past two decades due to their unprecedented multi-functional features. However, the macro-scale structural applications of these nanostructures have not yet come to full fruition due to the involvement of complex multi-scale computations and manufacturing. Recently, the researc...

This paper introduces the concept of negative stiffness inertial-amplifier-base-isolators to achieve enhanced broadband vibration control. Three physically different novel isolators, namely inertial amplifier base isolator (IABI), negative stiffness inertial amplifier base isolator (NSIABI), and negative stiffness base isolator (NSBI), are achieved...

Parametric excitation is introduced to amplify the external harmonic excitation and extend the capabilities of a nonlinear piezoelectric energy harvester device. To investigate the efficiency of the parametrically amplified energy harvester, the time responses of the voltage and power are computed using the state space formulation. It is assumed th...

Parametric excitation is introduced to amplify the external harmonic excitation and extend the capabilities of a nonlinear piezoelectric energy harvester device. To investigate the efficiency of the parametrically amplified energy harvester, the time responses of the voltage and power are computed using the state space formulation. It is assumed th...

Metadamping is the phenomenon of either enhanced or diminished intrinsic dissipation in a material stemming from the material's internal structural dynamics. It has been previously shown that a locally resonant elastic metamaterial may be designed to exhibit higher or lower dissipation compared to a statically equivalent phononic crystal with the s...

A novel method for characterising and propagating system uncertainty in structures subjected to dynamic actions is proposed, whereby modal shapes, frequencies and damping ratios constitute the random quantities. The latter, defined in the modal subspace rather than the full geometrical space, reduce the number of the random variables and the size o...

The stochastic behaviour of materials and loading is of great importance for buckling and analysis of prestressed beam and frame structures. In this paper, the stochastic stiffness and stress stiffness matrices are developed for stochastic analysis and buckling analysis. The bending rigidity and the buckling load are modelled as stochastic fields....

Honeycomb lattice structures are lightweight and have high strength to weight ratio. Hence, such structures have gathered a significant amount of attraction over the last decade. Many experimental and analytical studies have been carried out to determine the in-plane elastic properties of these lattice structures. Once manufactured, it is impossibl...