Clamped Conditions Research Articles

Pharmacokinetic and pharmacodynamic bioequivalence of Gan & Lee insulin analogues aspart (rapilin®), lispro (prandilin®) and glargine (basalin®) with EU- und US-sourced reference insulins.

For the successful approval and clinical prescription of insulin biosimilars, it is essential to show pharmacokinetic (PK) and pharmacodynamic (PD) bioequivalence to the respective reference products sourced from the European Union and the United States. Three phase 1, randomized, double-blind, three-period crossover trials compared single doses of the proposed biosimilar insulin analogues aspart (GL-Asp, n = 36), lispro (GL-Lis, n = 38) and glargine (GL-Gla, n = 113), all manufactured by Gan & Lee pharmaceuticals, to the respective EU- and US-reference products in healthy male participants (GL-Asp and GL-Lis) or people with type 1 diabetes (GL-Gla). Study participants received 0.2 U/kg (aspart and lispro) or 0.5 U/kg (glargine) of each treatment under automated euglycaemic clamp conditions. The clamp duration was 12 h (aspart and lispro) or 30 h (glargine). Primary PK endpoints were the total area under the PK curves (AUCins.total ) and maximum insulin concentrations (Cins.max ). Primary PD endpoints were the total area under the glucose infusion rate curve (AUCGIR.total ) and maximum glucose infusion rate (GIRmax ). Bioequivalence to both EU- and US-reference products were shown for all three GL insulins. Least squares mean ratios for the primary PK/PD endpoints were close to 100%, and both 90% and 95% confidence intervals were within 80%-125% in all three studies. There were no noticeable differences in the safety profiles between test and reference insulins, and no serious adverse events were reported for the GL insulins. GL-Asp, GL-Lis and GL-Gla are bioequivalent to their EU- and US-reference products.

Unraveling thermoelastic performance of the multi-directional functionally graded composite structure by data-driven deep-learning approach

Multi-directional functionally graded materials (MD-FGMs) are a brand-new family of sophisticated composites with continually changing structural and mechanical properties but no internal boundaries and interfacial stress concentrations. This study is the first to examine the effects of an instantaneous thermal shock on the thermo-elastodynamic response of a multi-directional functionally graded (MD-FG) doubly curved panel resting on an elastic substrate due to the remarkable properties of these advanced materials. The peripheral discontinuity at the boundaries between the loaded and unloaded surfaces as well as the shear coupling between the various Winkler-spring components are both taken into account in this proposed mode of the Kerr-type elastic substrate. Through the use of 3D-DQA, the system’s equations may be solved for both the simply supported and the completely clamped boundary conditions. For the first time, it is examined how several thermal shock models, such as cosinusoidal, sinusoidal, and Heaviside functions, impact how the system’s stress and deflection parameters fluctuate. The authors of this paper provide a unique strategy for enhancing the computing efficiency of the approach by constructing a deep-learning-based method on the data produced by 3D-DQT and Laplace transform at specified locations due to the dynamic nature of the issue. In order to decrease the mechanical excitation of the existing curved structure brought on by thermal shock, some advice for relevant industries is offered at the conclusion.

Analytical solution for the bending problem of micropolar plates based on the symplectic approach

Abstract An analytical solution for the bending problem of micropolar plates is derived based on the symplectic approach. By applying Legendre's transformation, we obtain the Hamiltonian canonical equation for the bending problem of a micropolar plate. According to the method of separation of variables, the homogenous Hamiltonian canonical equation can be transformed into an eigenvalue problem of the Hamiltonian operator matrix. We derive the eigensolutions of the eigenvalue problem for the simply-supported, free and clamped boundary conditions at the two opposite sides. Based on the adjoint symplectic orthogonal relation of the eigensolutions, the solution of the bending problem of micropolar plate is expressed as a series expansion of eigensolutions. Numerical results confirm the validity of the present approach for the bending problem of micropolar plates under various boundary conditions and demonstrate the capability of the proposed approach to capture the size-dependent behavior of micropolar plates.

Simulation of flexural-gravity wave propagation for elastic plates in shallow water using an energy-stable finite difference method with weakly enforced boundary and interface conditions

We introduce an energy stable, high-order-accurate finite difference approximation of the dynamic, pure bending Kirchhoff plate equations for complex geometries and spatially variable properties. We utilize the summation-by-parts (SBP) framework to discretize the biharmonic operator with variable coefficients, with attention given to free and clamped boundary conditions and corner conditions. Energy conservation is established by combining SBP boundary closures with weak enforcement of the boundary and interface conditions using a penalty (simultaneous approximation term, SAT) technique. Then we couple the plate equations to the shallow water equations to study flexural-gravity wave propagation, and prove that the semi-discrete system of equations is self-adjoint. We demonstrate the stability and accuracy properties of the method on curvilinear multiblock grids using the method of manufactured solutions. The method, which we provide in an open-source code, is then used to model ocean wave interactions with the Thwaites Glacier and Pine Island Ice Shelf in the Amundsen Sea off the coast of West Antarctica.

Large amplitude free vibration analysis of circular arches with variable thickness

This study aims to investigate the large amplitude nonlinear vibration of variable thickness arches with different cross-sectional shapes under different boundary conditions. The governing equations of the arches are derived using Hamilton's principle by considering their geometric nonlinearities. Then, the differential quadrature method (DQM) is employed for the discretization to obtain the ordinary differential equations of motion for the circular arches with variable thickness. The theoretical model is validated by comparing the linear and nonlinear natural frequencies of arches. The nonlinear vibration characteristics of arches are solved using the direct iteration scheme. The effects of the slenderness ratio, modified slenderness ratio of the arch, and variable thickness parameters under different cross-sectional shapes on the nonlinear to linear frequency ratios of the arches with clamped and pin-ended boundary conditions are investigated. The results indicate that appropriate variable thickness parameters can improve the linear frequency and the nonlinear to linear frequency ratio of arches, which offers some suggestions for the design of variable thickness arches.

Buckling analysis of sandwich plates reinforced with various loading of multi-walled carbon nanotubes

The current investigation aims to examine the buckling behavior of sandwich structures reinforced with faces containing varying weight percentages (wt.%) of multi-walled carbon nanotubes (MWCNT), through the combined employment of experimental and numerical analysis techniques. In particular, the numerical analysis is executed through the implementation of the generalized differential quadrature method (GDQM). The study first determines the mechanical properties of the pure and reinforced samples via experimental tests. The buckling equations of the sandwich plate are then derived using the Frostig approach and a high-order shear deformation theory (SDT) for the flexible core. The continuity conditions between the faces and the core are considered to obtain the structural equations of the system, and Lagrange coefficients are introduced to enhance the accuracy of the governing equations. Subsequently, the study investigates the impact of various parameters, such as core thickness, aspect ratio, different boundary conditions (BC), and the addition of MWCNT nanoparticles on the critical buckling load of the system, utilizing the mechanical properties obtained for the composite faces. The present investigation reveals that the incorporation of MWCNT into the composite matrix brings about notable enhancements in the mechanical characteristics of sandwich structures. Specifically, the elastic modulus and ultimate strength of the faces are found to increase following the addition of MWCNT. Additionally, the critical buckling load of the sandwich plates is observed to rise with an increase in aspect ratio and length-to-thickness ratio, while a decrease in axial load yields similar results. The clamped boundary condition has higher critical buckling loads than the simply supported boundary condition. The addition of MWCNT nanoparticles decreases the dimensionless critical buckling force as the b/a ratio increases. Finally, the reported results of the current investigation present noteworthy findings about the advancement and improvement of sandwich composite structures to meet various application requirements.

Three-dimensional analysis of FG-CNTRC shell subjected to internal pressure utilizing Carrera Unified Formulation

This work focuses on the bending examination of three-dimensional (3D) functionally graded carbon nanotube (CNT) reinforced composite (FG-CNTRC) cylindrical shell exposed to internal pressure. The composite cylindrical shell is assumed to be reinforced in the longitudinal axis. Mechanical properties of the constituents are applied based on the modified rule of the mixture. Distribution of CNTs across the shell thickness is assumed to be uniform and three types of functionally gradients. The governing equations are developed using the Principle of Virtual Displacements (PVDs) based on Carrera’s Unified Formulation (CUF) and then differential quadrature method (DQM) is used to solve the governing equations for different combinations of simply supported and clamped boundary conditions. The comparison studies between the obtained results and those available in the literature demonstrate the accuracy and computational efficiency of the present formulation and method. The roles of different factors including the volume fraction of CNTs ( V CN * ), boundary conditions, distributions of CNTs, length-to-radius ratios ( L / r ), and mechanical loads, are investigated in the outcomes. The results illustrate that the non-dimensional maximum deflections of functionally graded (FD) distributions are higher than the uniform distributions for different boundary conditions.

Novel Approach-Based Sparsity for Damage Localization in Functionally Graded Material

Model-based approaches have been widely employed in damage detection and localization studies. However, alternative techniques, such as built-in online detection methods, hold promise for future advancements in structural health monitoring technologies. In this research paper, we present a dynamic algorithm specifically designed for accurate damage localization in functionally graded plates. The suggested method involves the creation of a grid matrix that captures the dynamic response of the structure over time. Subsequently, an optimization process is performed using a linear equation that incorporates the information contained within the grid, enabling the precise localization of damage. To address the inherent sparsity of the localization nature, we utilize the FISTA (fast iterative shrinkage-thresholding algorithm) as a problem solver. The effectiveness of our approach is evaluated through experimental tests on a functionally graded plate with clamped free boundary conditions. Multiple damage scenarios are investigated, including cases with damage signals on and off-the-grid. The results demonstrate that our proposed approach is capable of accurately predicting the position of damage, indicating its suitability for application in low-size data systems.

Effect of corrosive environment on mechanical properties of polymer-based nanocomposite: Analytical and experimental study

The aim of this research is to investigate the critical buckling force of a sandwich structure with the addition of nanoparticles to composite faces in an acidic environment. The effect of adding 3 wt% silica and clay nanoparticles in fabrication of composite is compared in mechanical properties and sandwich buckling; And the critical buckling load is obtained by using low order piecewise shear deformation theory (PSDT). In the experimental study, significant degradation is observed after acid immersion, and the addition of 3 wt% nanoclay shows better performance by improving the durability of the structure against changes in the length and mass of the composite specimens. It is shown that the prediction of buckling is a function of mechanical properties, mass absorption, and βacid in acidic immersion, and to determine the buckling response, the mass absorption diagram of the layers, needs to be available. The results imply that the addition of nanoparticles changes the buckling behavior of the sandwich structure, such that the sandwich with silica faces requires more mass absorption than other sandwiches for buckling, however, this composite face have a faster mass absorption rate, which makes their buckling response almost the same as other sandwiches. However the sandwich with the face containing 3 wt% nanoclay still performs better in improving the buckling of the sandwich plate. The findings of the study indicate that immersion in 5% sulfuric acid for 30 days significantly reduced the critical buckling force of composite sandwiches by 63.81–82.25% under simply supported boundary conditions and 29.44–38.97% under clamped boundary conditions. To develop the LOPSDT theory, Ritz method was applied to for clamped sandwich, witch results have been shown very good agreement in validation with the ANSYS solution.

Free vibration analysis of the sandwich structured composite annular plates: Numerical and experimental investigation

Sandwich structures are interesting structural elements due to their high stiffness-to-weight ratio, high fatigue resistance, and excellent vibration characteristics. The aerospace industry relies heavily on these types of structures considering the different optimized materials and shapes available for sandwich construction. In the present study, vibration aspects of annular sandwich structures with composite laminates and a 3D printed honeycomb core are investigated in both the numerical and experimental methods. Amongst the various shapes of sandwich structures, annular sector plates are predominantly used in the construction of modern bridges, aircrafts, and automobile parts. Furthermore, the investigation of annular sandwich plates featuring GFRP facesheet and 3D printed PLA cores are studied in a very limited extent. In order to obtain the sector plates experimentally, Glass Fiber Reinforced Polymer (GFRP) laminates are fabricated by hand layup techniques, and the 3D printing Poly-lactic Acid (PLA) honeycomb core is manufactured using Fused Deposition Modelling (FDM). The material properties of honeycomb core and composite skins are estimated with the help of Gibson formulation and rule of mixture, respectively. Based on available literature, the analysis approach is validated through numerical analysis using ANSYS Finite Element (FE) software. Also, the frequency responses of annular sandwich plate were measured in both experimental and numerical analysis and the results showed good agreement. However, in order to describe the effectiveness of annular composite sandwich plates, parametric studies are carried out in terms of natural frequencies and mode shapes with different configurations of core geometry, ply orientation, boundary constraints, and inner to outer radius ratio. The research outcome highlights that the optimum angle ply orientation, core height of 12.5 mm with clamped–clamped condition and inner to outer radius of 0.75 mm yields better structural stiffness.

Nonlinear nonlocal damped free and forced vibrations of piezoelectric SWCNTs under longitudinal magnetic field due to surface effects using a two steps perturbation method

In the present work, damped free and forced vibrations of single-walled piezoelectric carbon nanotubes under longitudinal magnetic field due to surface effects surrounded on a non-linear viscoelastic medium using the nonlocal Euler-Bernoulli beam theory and multiple time scales method are investigated. Lorentz force equation is used to obtain the vertical force due to the applied voltage to the system. The surface effects as well as a combinational non-linear viscoelastic foundation are considered, and finally, the dynamic equilibrium equations are used, and non-linear equations of motion are extracted. In the following, the Galerkin and multiple time scales methods are used, and finally, analytical solutions are extracted as the non-linear free and forced vibrational responses of the system. The relevant coefficients of the extracted analytical solutions are discovered for two both simple support (S-S) and clamped (C-C) boundary conditions. In the following, , and the effects of the different parameters such as non-local parameter as well as electric-magnetic fields, effect of hardness-linear damping parameters of nonlinear considered viscoelastic foundation, applied magnetic field, base modes for different forms considering surface effects, and etc. will be studied. As one the results of this study, the presence of a non-local parameter has increased the curvature deviation to the right and the stiffening effect. In other words, the non-local parameter is a factor to increase the nonlinear effect of the system. Also, it is predictable that as the load affect position moves away from the center of the single-walled piezoelectric carbon nanotube toward the supports, the amplitude of the dynamic response decreases significantly, and this relative reduction is greater for the C-C boundary condition than for the S-S boundary condition. It is also important to note that the location of the load has no effect on the rate of deviation of the curve peak, and the degree of nonlinearity of the vibrational response of the system.

219-OR: Glucagon Counterregulation in a Hypoglycemic Clamp in Type 1 Diabetes Is Increased by ZT-01, a Novel Somatostatin Receptor 2 Antagonist—A Phase 1b Study

This study evaluated the effect of ZT-01 on glucagon counterregulation during hypoglycemia in adults with type 1 diabetes, in a Phase 1b randomized, three-arm, double-blind crossover trial in 23 hypoglycemia aware adults with T1D. Participants underwent three hypoglycemic clamp procedures with 3 or 20 mg ZT-01 or placebo dosed 1 h prior to stepwise glucose clamp conditions using variable rate IV insulin infusion: euglycemia (5.0 ± 0.5 mmol/L), level 1 (3.5 ± 0.3 mmol/L, L1), and level 2 hypoglycemia (2.6 ± 0.2 mmol/L, L2). With ZT-01, peak glucagon increased by up to 15.1 ± 10.5 and 27.1 ± 17.3 pg/mL, in L1 and L2 hypoglycemia, respectively, compared with no increase in L1 and an 8.4 ± 8.4 pg/mL increase in L2 hypoglycemia with placebo (p<0.0001, figure). A counterregulatory response of increased glucose level coinciding with an increased glucagon level was observed more frequently with ZT-01 than placebo. No clinically significant effects on other counterregulatory hormones or hypoglycemia symptom scores were observed with ZT-01. A transient rise in glucagon and blood glucose was observed with ZT-01 post-dose prior to hypoglycemia. No SAEs were reported and no TEAEs were observed with ZT-01. This study demonstrates proof-of-concept that ZT-01 significantly enhances the defective counterregulatory response in people with T1D during L1 and L2 hypoglycemia. Disclosure A.Abitbol: Advisory Panel; Abbott Diabetes, Lilly Diabetes, Dexcom, Inc., Novo Nordisk Canada Inc., Janssen Pharmaceuticals, Inc., Research Support; Abbott Diabetes, Lilly Diabetes, Zucara Therapeutics, Novo Nordisk Canada Inc., Moderna, Inc., Senseonics, Speaker's Bureau; Boehringer Ingelheim (Canada) Ltd., Lilly Diabetes, Amgen Canada, Dexcom, Inc., Novo Nordisk Canada Inc., HLS Therapeutics Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Sanofi. S.Peers: Employee; Zucara Therapeutics. E.Simonson: None. M.Midmer: Board Member; Zucara Therapeutics, Employee; Zucara Therapeutics, Stock/Shareholder; Zucara Therapeutics. M.Riddell: Advisory Panel; Zealand Pharma A/S, Zucara Therapeutics, Indigo Diabetes, Consultant; Lilly Diabetes, Eli Lilly and Company, Jaeb Center for Health Research, Speaker's Bureau; Dexcom, Inc., Novo Nordisk, Sanofi, Stock/Shareholder; Supersapiens, Zucara Therapeutics. R.Liggins: Employee; Zucara Therapeutics, Stock/Shareholder; Zucara Therapeutics.

1543-P: The Effect of Insulin Resistance on Brain Glucose Uptake—A Systematic Review and Meta-analysis

Objective: We investigated the association between peripheral insulin resistance (IR) and brain glucose uptake (BGU) and further determined if testing condition (fasting vs. hyperinsulinemic-euglycemic clamp) was a moderator of the association. Methods: A systematic search was conducted in PubMed, Embase, Cochrane Library, and Web of Science, studies assessing an association between measures of or clinical proxies for IR (e.g. diabetes and obesity) and BGU were included. Effect sizes were standardized and transformed into correlation coefficients and a random effect meta-analysis performed. Further, a subgroup analysis on testing condition was conducted. Results: Twenty-one studies (n = 3,620) were included in the meta-analysis. The pooled correlation (-0.13 [95% CI: -0.37; 0.12], p=0.3) showed a substantial heterogeneity (I2 = 98%). Subgroup analysis revealed that IR negatively correlated with BGU when subjects were examined at fasting conditions (-0.42 [95% CI: -0.59; -0.21], I2 = 99%) and positively correlated when subjects were examined during a hyperinsulinemic-euglycemic clamp (0.53 [ 0.38; 0.66], I2 = 47%)(figure 1). Test condition significantly moderated the association (p <0.01) and explained 55% of the heterogeneity. Conclusion: Across the studies IR results in abnormal BGU in both fasting and hyperinsulinemic states, clamp conditions reverse the low BGU in IR. Disclosure N.J.Jensen: None. A.J.Porse: None. H.Speyer: None. J.Krogh: None. M.Gejl: None. A.H.Gjedde: None. J.Rungby: Advisory Panel; Abbott, Consultant; Novo Nordisk, Speaker's Bureau; Boehringer-Ingelheim, AstraZeneca.

820-P: The Proposed Insulin Lispro Biosimilar GN1101DP Shows Pharmacokinetic (PK) and Pharmacodynamic (PD) Bioequivalence to Humalog in Caucasian and Chinese Healthy Subjects

This randomized, double-blind, cross-over study compared PK/PD-properties of Humalog and GN1101DP, a proposed insulin lispro (INS) biosimilar with an identical primary structure and high physicochemical and bio-functional similarity to Humalog. Thirty-five Caucasian and 13 Chinese healthy subjects completed the study and received a single dose of 0.3 U/kg of GN1101DP and Humalog under euglycemic automated glucose clamp conditions (ClampArt®, plasma glucose (PG) target 81 mg/dL, clamp duration 12 hours post-dose, wash-out period 2-14 days between the two dosings). Plasma INS concentrations were determined by tandem ultra performance liquid chromatography-mass spectrometry. GN1101DP demonstrated both PK- and PD-bioequivalence to Humalog with superimposable INS concentration and glucose infusion rate (GIR) profiles, point estimates close to 100%, and 90% confidence intervals were within the pre-defined similarity range of 80-125%. Bioequivalence was observed in all and also separately in Caucasian and Chinese subjects (Figure). Clamp quality was high (mean PG-variations of ~5% and deviations from target <0.6 mg/dL). Both lispro formulations were well tolerated. No injection site reactions occurred. In conclusion, GN1101DP demonstrated PK- and PD-bioequivalence to Humalog in Caucasian and Chinese subjects. Disclosure T.Heise: Advisory Panel; Novo Nordisk, Consultant; Gan & Lee Pharmaceuticals, Research Support; Adocia, AstraZeneca, Biocon, Crinetics Pharmaceuticals, Inc., Eli Lilly and Company, Genova, Novo Nordisk, Sanofi, Zealand Pharma A/S, Speaker's Bureau; Eli Lilly and Company, Novo Nordisk. E.Zijlstra: Other Relationship; Eli Lilly and Company, Speaker's Bureau; Gan & Lee Pharmaceuticals, Novo Nordisk A/S. G.Andersen: None. S.B.Selker: None. C.Shen: None. Y.Wang: None. Funding Genova Biotech Pvt. Ltd.

Nonlinear thermal post-buckling analysis of rectangular FG plates using CUF

In this study, a numerical analysis examines the thermal post-buckling response of rectangular functionally graded (FG) plates. Since the post-buckling is analyzed in a thermal environment, temperature distribution across the thickness is computed by an accurate numerical method. Here, for the geometrically nonlinear analysis because of assuming large displacement, FEM is utilized according to Carrera Unified Formulation (CUF), a precise formulation and higher-order deformation theory. The principle of virtual work is employed to achieve the nonlinear equilibrium equations. The governing equations are solved by operating the arc-length method. The influence of parameters such as geometric aspect ratio, length-to-thickness ratio, boundary conditions, type of temperature distribution, and volume fraction index on the FG plates’ temperature-deflection path has been investigated. In addition, a comparison among the present study method with another reference about thermal post-buckling and also linear buckling analysis (LBA) is performed. Nonlinear post-buckling analysis shows that the bifurcation point occurs only at fully clamped boundary conditions and low aspect ratios. It proved the results of LBA in the mentioned state are verifiable. The outcomes confirm the usefulness of utilizing CUF on thermal post-buckling since the temperature curves in the figures are at a lower level compared to the similar reference.

Nonlocal couple stress-based meshless collocation model for nonlinear dynamic performance of microbeam-type piezoelectric energy harvesters

The prime aim of the current exploration is that to analyze the size-dependent nonlinear dynamics of microsize laminated bridge-type piezoelectric energy harvesters containing a passive core made of an agglomerated nanocomposite and piezoelectric surface layers under a time-dependent mechanical load. For this purpose, the both nonlocal and couple stress tensors are incorporated to the classical quasi-3D shear flexible beam theory to model microsize beam-type laminated energy harvesters. After that, a numerical solution methodology based on the meshless collocation method is employed to discretize the obtained size-dependent nonlinear equations via using a coalesce basis function including polynomial and multiquadric parts on the basis of the Chebyshev node distribution scheme to remove any possible singularity. The nonlinear time histories relevant to the induced lateral deflection and extracted voltage are plotted in the presence and absence of the nonlocal and couple stress tensors as well as various values of the agglomeration constants relevant to the nanocomposite passive core of microsize energy harvesters. One can find that by increasing the cluster volume fraction, the effect of the nonlocal stress tensor on the extracted voltage from the microsize energy harvester increases from +16.50% to +17.53% in the case of simply supported end conditions, and from +21.84% to +22.99% in the case of clamped end conditions. In addition, the effect of the couple stress tensor enhances from −22.21% to −23.09% in the case of simply supported end conditions, and from −27.15% to −27.94% in the case of clamped end conditions.

Effect of interaction between polarization direction and inclined force on the dynamic stability of a pre-stressed piezoelectric plate

The current study deals with forced vibration analysis of a pre-stressed piezoelectric plate with finite lengths resting on a rigid foundation, exposed to an inclined time-harmonic force. The present investigation is modeled according to a new theoretical consideration in the context of the three-dimensional linearized theory of elasticity for solids under initial stress (TLTESIS). It is assumed that the plate exhibits a polarization effect in both vertical and horizontal directions to the top surface and there is an exact clamping condition at the interface between the plate and the rigid foundation, that is, no jumping in the quantities. For obtaining the governing and boundary condition equations of our problem, the virtual work principle is used according to Hamilton's principle and the piecewise homogeneous body model. The three-dimensional displacement-based finite element model is developed for solving the system of partial differential equations and analyzing the dynamic behavior of the plate. The reliability of the solution procedure is proved by convergence analysis and comparing the results to the current literature. The target of the paper for surveying the numerical results and findings is divided into two sections. The first one presents the influence of the inclination of the dynamic external force on the forced vibration characteristics of the current model. In the second one, the influence of inclination angle, thickness ratio, aspect ratio, and initial stress parameter on the frequency response of the harmonic force are investigated in detail. As a desirable result for the designer, while a decrease in the angle of the force with the vertical axis exceeds the resonant mode of the stress, increasing values of the initial stress prevents that mode.

A Nonlinear Free Vibration Analysis of Functionally Graded Beams Using a Mixed Finite Element Method and a Comparative Artificial Neural Network

Based on the Hamilton principle combined with the Timoshenko beam theory, the authors developed a mixed finite element (FE) method for the nonlinear free vibration analysis of functionally graded (FG) beams under combinations of simply supported, free, and clamped edge conditions. The material properties of the FG beam gradually and smoothly varied through the thickness direction according to the power-law distributions of the volume fractions in the constituents, and the effective material properties of the FG beam were estimated using the rule of mixtures. The von Kármán geometrical nonlinearity was considered. The FE solutions of the amplitude-frequency relations of the FG beam were obtained using an iterative process. Implementing the mixed FE method showed that its solutions converged rapidly and that the convergent solutions closely agreed with the accurate solutions reported in the literature. A multilayer perceptron (MP) back propagation neural network (BPNN) was also developed to predict the nonlinear free vibration behavior of the FG beam. After appropriate training, the prediction of the MP BPNN’s amplitude-frequency relations was entirely accurate compared to those obtained using the mixed FE method, and its central processing unit time was less time-consuming than that of the mixed FE method.

Realization of high performance PZN-PT single crystal based piezoelectric flexural mode hydrophone for underwater sensor applications

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d33 > 2000 pm V−1) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.

Thermo-Electro-Mechanical Analysis of Micropolar FGP Cylindrical Shell Covered with Piezoelectric Actuator Layers

An investigation is performed in this paper to analyze the nonlinear thermo-electro-mechanical response of long sandwich cylindrical shells with functionally graded porous (FGP) core and thin piezoelectric actuator layers. The FGP core of the sandwich shell is assumed to be temperature- and microstructure-dependent. It is assumed that the sandwich shell is subjected to uniform lateral pressure loading in a thermo-electrical environment. The equilibrium equations of the shell with infinite length are established with the aid of the virtual displacement principle and von Kármán kinematic assumptions. The governing equations are obtained in terms of displacement components based on the first-order shear deformation model of shallow cylindrical shells and the modified couple stress theory. These nonlinear differential equations are analytically solved for a sandwich shell having both the simply-supported and clamped–clamped edge conditions by employing a two-step perturbation technique. Analytical closed-form solutions are determined as a relationship including the load parameter and the mid-span deflection. The comparison examples are made with the existing results in the literature for a simple functionally graded shell, where good agreement is obtained. It is shown that the nonlinear response of the sandwich shell is highly dependent upon the temperature variation, power law index, porosity coefficient, couple stress parameter, piezoelectric layers, and geometrical parameters of the shell.