Analytical Structural Model Research Articles

Modeling thermal and buckling behavior in electrothermal bimorphs

Abstract Buckling is a structural phenomenon that can induce significant motion with minimal input variation. Electrothermal bimorphs, with their simple input and compact design, can leverage out-of-plane buckling motion for a broad range of applications. This paper presents the development of analytical electrothermal and structural models for such bimorphs. The electrothermal model calculates the temperature distribution within the bimorph caused by electrothermal heating, providing a 2D explicit analytical expression for estimating temperature along the bimorph’s length and cross-section. Nonhomogeneous heating leads to varying strains, which induce axial forces and moments along the bimorph’s neutral plane, varying with thermal expansion. The structural model derives the governing equation of deformation for the bimorph by analyzing internal strains and stresses resulting from deformation, electrothermal heating, and residual stresses. An analytical solution for deflection is obtained, incorporating infinite sums of heating and buckling modes, with closed-form equivalent expressions when possible. The bimorph’s behavior under different scenarios of residual stresses and electrothermal heating is elucidated based on the analytical model. Comparisons with Finite Element simulations demonstrated excellent agreement, highlighting the high accuracy of the proposed models.

Cybersecurity Awareness Model with Methods: Analytical Hierarchy Process and Structural Equation Model

This era of revolution has influenced all sectors of society, including education, where technological advancements are now integral to online teaching and learning. However, not everyone fully understands the potential negative impacts of internet usage. The purpose of this research was to investigate and analyze cybersecurity awareness. The study focused on students at Aerospace Air Marshal Suryadarma University. The research employed a quantitative design, either descriptive (where subjects are typically measured once) or experimental (where subjects are measured multiple times). A descriptive study establishes a relationship between variables, while an experimental study determines causation. To analyze the collected data, SEM AMOS was utilized to measure students' awareness of cybersecurity. The study focused on five key areas: (a) regulation, (b) internet usage, (c) password security, (d) data security, and (e) cyberattacks. Based on the research framework and these focus areas, several indicators were developed for the study. The findings concluded that students are aware of cybersecurity issues.

Viscoelasticity of hydrating shotcrete as key to realistic tunnel shell stress assessment with the New Austrian Tunneling Method

The New Austrian Tunneling Method (NATM) essentially rests on observational information concerning displacements measured in selected positions at the inner surface of shotcrete tunnel shells. The combination of these measurements with advanced material and structural mechanics, in the course of so-called hybrid methods, have successfully delivered, for more than 20 years, practically relevant estimations of internal and external forces and corresponding degrees of utilization. The reliability of the latter, however, may crucially depend on the used material model. Based on a recently proposed analytical structural mechanics model [Acta Mech 233, 2989–3019 (2022)], and focusing on the benchmark example of measurement cross section MC1452 of the Sieberg tunnel, driven in the 1990s in Miocene clay marl, the present paper compares the estimations of forces and degrees of utilization arising from differently refined constitutive concepts, namely (i) aging elasticity, (ii) aging linear viscoelasticity, and (iii) aging nonlinear viscoelasticity. It turns out that only the consideration of aging nonlinear viscoelastic material behavior provides access to realistic values for the degree of utilization, being lower than one. Simpler material models would indicate local material failure, which was not observed in situ.

Application of an Integrated Analytic Hierarchy Process and Interpretive Structural Modeling Methodology for Selecting Energy-Saving Methods

Application of an Integrated Analytic Hierarchy Process and Interpretive Structural Modeling Methodology for Selecting Energy-Saving Methods

Vibro-acoustic control of a programmable meta-shell with digital piezoelectric shunting

In this paper, a programmable piezoelectric meta-shell is designed to actively control the structural and sound radiation responses. The meta-shell consists of a cylindrical shell, Macro-fiber Composite (MFC) patches and digital shunting circuits. Due to the electro-mechanical coupling effect of the MFC patches, the mechanical properties of the meta-shell structure can be tuned by changing the electric field. The high-order digitally resonant circuits are designed to realize programmable control of the bandgap behaviors of the meta-shell. An analytical structural dynamic model for analyzing the vibration and radiated sound responses of the programmable piezoelectric meta-shell in light fluid is established. The vibro-acoustic characteristics of the meta-shell with the piezoelectric shunting and the effects of electric parameters (including dimensionless gain and electric damping ratio) on the structural and acoustic control performances of the shell are discussed. Experiments on the vibration and acoustic control of a programmable piezoelectric meta-shell are carried out to verify the high-order bandgap characteristic and its programmability. The experimental results demonstrate that the vibration and sound radiation responses of the shell can be effectively suppressed in multiple frequency bands.

Non-unimodal and non-concave relationships in the network Macroscopic Fundamental Diagram caused by hierarchical streets

Unimodal, concave relationships between average network productivity and accumulation or density aggregated across spatially compact regions of urban networks—so called network Macroscopic Fundamental Diagrams (MFDs)—have recently been shown to exist on homogeneous street networks. When present, MFD relationships facilitate the modeling of traffic congestion at a regional level and have led to the development of various regional traffic control strategies. However, real street networks are not homogeneous—they generally have a hierarchical structure where some streets (e.g., arterials) promote higher mobility than others (e.g., local roads). This paper examines how the presence of hierarchical roadway structures may potentially cause non-unimodal patterns in a network's MFD. These are observed using three types of tools: analytical models of simple network structures, simulations of various idealized roadway networks, and empirical data. The impacts of street hierarchy depend on how vehicles use different roadway types to move within the network; i.e., their routing strategy. The findings suggest that the presence of roadway hierarchies may lead to MFDs that have non-unimodal or non-concave patterns on the free-flow branch when vehicles route themselves according to user equilibrium principles, which is closest to what would be observed in realistic situations. Such patterns are contrary to what is traditionally assumed in most MFD-based modeling frameworks. However, the unimodal and concave MFD should be expected under system optimal routing conditions that maximize network productivity for a given traffic state.

Design, fabrication and mechanical properties of a 3D re-entrant metastructure

A 3D re-entrant honeycomb structure was designed in a simple configuration by introducing a spatial angular design parameter. Mechanical responses under uniaxial compression of it at constant spatial angle (α) and different re-entrant angles (θ) were investigated both experimentally and theoretically. Designed lattice auxetic structures with high shape fidelity were fabricated using selective laser sintering (SLS) of PA 2200 powder. The produced samples exhibited negative, zero, and positive Poisson's ratios depending on a selected θ value, and their mechanical properties varied over a wide range. Bend- and buckling-dominated deformation mechanisms of the struts have been observed under compression. Additionally, the analytical models of re-entrant honeycomb structures effectively illustrated the quantitative relationships between their mechanical properties (Young’s modulus (E) and Poisson’s ratio) and the design parameter θ. The results presented in this study would provide a reference to the customized design of the porous auxetic structures with unique mechanical properties.

Two analytical structural models of the connecting rod cap

The mathematical models available in the pertinent literature for designing the cap of a connecting rod are critically examined, and it is shown that some currently adopted assumptions are inaccurate. Spurred by these critical remarks, two more realistic mathematical models are developed of the contact between the crankpin and the cap. In both models, the crankpin is modelled as rigid, and the cap is idealized as a purely flexural, curved beam of constant cross-section, in progressive contact with the crankpin. In the first model, the cap is mimicked as a twice-statically redundant structure solved with the Castigliano theorem. The cap structural response is mechanically examined starting from the central part of the cap-crankpin contact. In the second model, the cap is mimicked as a statically determined structure. Particular attention is paid to the cap change of curvature when moving along the cap axis. The beginning of the cap-crankpin contact is determined by requiring that the curvature of the deformed cap equal the curved border of the crankpin. A result common to the two approaches is the definition of a combined factor summarizing the mechanical effect of several variables, namely the total load, the initial clearance, Young’s modulus, and the cap geometry; the last factor is recapped by the radius defining the centre of mass, and by the moment of inertia. To evidence the merits and limits of the two approaches, the extent of the cap-crankpin angular contact, and the value of representative cap stresses, are determined and compared to Finite Element (FE) forecasts. Furthermore, the effect of the ratio between the moment of inertia of the abutment and the cap central cross-section is investigated. This ratio influences the prediction of the contact angle; when the ratio is higher than 4, the numerical FE results significantly differ from the analytical calculations.

An SEM-ANP Multi-Criteria Evaluation Model for Mobile Advertising That Affect Purchase Intentions: Perspectives on the Values of Context Awareness and Flow Experience

Among the limited studies that have investigated flow experience in mobile advertising, the focus is cast on the value of advertising and the impact of flow experience. This study investigates the factors of mobile advertising that affect purchase intentions based on the value of context awareness and flow experience. First, a literature review of the corresponding studies and confirmatory factor analysis are combined to identify key factors that influence the purchase intentions of cell phones. Second, analytic network process (ANP) and structural equation modeling (SEM) are integrated into an SEM–ANP multi-criteria evaluation model. Results show that the weights for credibility, entertainment, focused immersion, and intrinsic interest are the highest. Furthermore, consumers believe that mobile advertising is a good informational reference for purchase decisions, and that the interaction of advertising value and the value of flow experience affect purchase intentions. Compared to informational advertisements, transformational advertisements are found to have a better effect on stimulating purchase intentions. Marketers are suggested to focus on transformational advertisements, supplemented by informational advertisements when designing mobile advertising campaigns.

The influence of shaping on the behavior of a mesh shell shaped as a one-sheeted hyperboloid

Introduction. The stress-strain state (SSS) of mesh shells that have the shape of a one-sheeted hyperboloid, consisting of one, two and three sections and subjected to vertical and wind loads coupled with their own weight is studied. The feature of these shells is the use of the Fibonacci number in their geometry, or in the ratio of their diameters and heights.
 Materials and methods. The position of rectilinear generatrices of shell depends on the angle of inclination of generatrices, which is determined by the mutual rotation of the upper and lower bases, and it determines various shapes of the structure. The stress-stain state of shells is found numerically using the LIRA–SAPR software package. The largest forces arising in the generatrices and the largest horizontal displacements of the upper edge of the shell, caused by wind loading, are compared.
 Results. Equations are obtained to identify the position of the generatrix and the size of the real semi-axis of the hyperboloid. Analytical models of shells with different inclinations of generatrices are provided. As a result of the data analysis, the shapes of shells, having different heights and numbers of storeys, are proposed to ensure their optimal strength and stiffness. If the structure is subjected to vertical loads and self-weight, the mutual rotation of upper and lower bases does not affect the SSS of e shells. When the wind load is applied, the situation is completely different. Hence, for single-section shells of medium height and high shells with optimal parameters of internal forces and displacements, the size of the real semi-axis coincides with the size corresponding to the “golden section”. At the same time, shells with a small angle of mutual rotation of the bases barely resist lateral loading. In two- and three-sectional shells, the value of the real half-axis is slightly greater.
 Conclusions. The use of mesh shells, having the shape of a one-sheeted hyperboloid that has the “golden section” ratio, allows obtaining more expressive structural solutions. Analytical models of such structures are presented.

A reasonable corrigendum on the previous article about the re-entrant and star-shape auxetic structures by theory and simulation

Auxetic structures are widely applied to absorb impact energy effectively. Changfang Zhao et al. proposed the auxetic structures of the concave hexagon and star shape. However, the analytical models of the auxetic structures were developed inaccurately, and some of their equations have been identified with mistakes. This paper is to correct the errors and verify the results calculated by the corrected equations with the results of finite element analysis simulation. In this paper, the Poisson's ratio and Young's modulus of two single-cell honeycomb and star structures and five nine-cell grid composite structures of the X-type, H-type, Sd-type, pure honeycomb, and star are calculated based on the Euler beam theory. Analytical models of the star and honeycomb structures have been corrected to calculate Young's modulus and Poisson's ratio.

Second-order approximation pseudo-rigid model of circular arc flexure hinge

The paper presents a novel pseudo-rigid model for describing the elasto-kinematic behaviour of circular arc flexure hinge subjected to a pure moment. The model is based on the kinematic study of flexure hinge large deflection using second-order motion invariants (polodes and inflection circle), which accurately describes the relative motion between the connected bodies. The proposed pseudo-rigid model has a single degree of freedom. It is an epicyclic arrangement with two rolling without slipping external circles with the same radius and a torsional spring with constant stiffness. Analytical formulas for computing the radius and the location of the two rolling circles and the rotational spring stiffness are deduced. The proposed model has been compared with analytical formulas and structural finite element models in different configurations. The results show very good accordance even for large deflections, confirming the model's effectiveness.

Nonlinear free vibration of functionally graded fiber-reinforced composite hexagon honeycomb sandwich cylindrical shells

In the present study, the nonlinear free vibration of functionally graded fiber-reinforced composite hexagon honeycomb sandwich cylindrical shells is investigated with consideration of the large-amplitude effect. First, an analytical model of such shell structures is proposed, which considers the functionally graded fiber-reinforced composite skins and a hexagon honeycomb core with their respective effective material properties being evaluated through the micromechanical model of Halpin-Tsai and the mixture law, as well as the modified Gibson's formula. Meanwhile, based on the first-order shear deformation theory and von Kármán geometrical nonlinear relations, the nonlinear partial differential governing equations are deduced via Hamilton’s principle, which is further discretized into several ordinary differential equations by the Galerkin approach. Subsequently, the static condensation technique is adopted to decrease the degrees of freedom, and the frequency-amplitude relationships are obtained by the multiple scale expansion method. Following the validation of the developed model via comparing the predicted results to literature ones, a detailed parameter study of critical geometric and material parameters on the nonlinear vibration characteristics of the structure is conducted, with some important conclusions being provided to weaken the nonlinear hardening-spring behavior of the structure.

Barriers of the Green Supply Chain Management Implementation: A Benchmark of Studies of Analytic Hierarchy Process and Interpretive Structural Modeling

Barriers of the Green Supply Chain Management Implementation: A Benchmark of Studies of Analytic Hierarchy Process and Interpretive Structural Modeling by Hamza Fahmy * , Mohamed Mazouzi, Ayoub Alami Masmoudi, Tamasna El Mehdi Mechanical department, Laboratoire de Mécanique, d'Ingénierie et d'Innovation (LM2I)-ENSEM, Casablanca, Morocco * Author to whom correspondence should be addressed. Journal of Engineering

Insight into energy dissipation behavior of a SDOF structure controlled by the pounding tuned mass damper system

AbstractThe purpose of this paper is to present an innovative insight into the behavior and energy dissipation mechanism of a single‐degree‐of‐freedom (SDOF) structure controlled by pounding tuned mass damper (PTMD). In this study, a shake table test was conducted to investigate energy response of the SDOF structure incorporated with PTMD and subjected to seismic excitations. Moreover, SDOF structure and the updated analytical structural pounding force model based on viscoelasticity of materials have been investigated for parametric studies, including dynamic parameters of the primary structure, properties of PTMD, and characteristics of the earthquake records. The influence of these parameters has been discussed in details in this paper. The results showed that energy can be dissipated by PTMD as well as via the three traditional ways of TMD. The energy dissipated by PTMD keeps increasing during excitation, which is similar to the process of energy dissipated by damping mechanism. Furthermore, energy dissipated by damping and PTMD are nearly equal, and the two types of energy dissipation predominate the behavior of the system. Hysteretic, recoverable elastic strain and kinetic energy of the controlled structure diminish to very low level during earthquakes.

Probabilistic Seismic Assessment of Moment Resisting Steel Buildings Considering Soft-story and Torsional Irregularities

In this study, the fragility curves were developed for three-, five-, and eight-story moment resisting steel frame structures with considering soft story and torsional irregularities during the earthquake mainshock to assess the probabilistic effects of irregularities in plan and height of steel structures. These models were designed according to Iranian seismic codes. 3D analytical models of steel structures were created in the OpenSees software platform and Incremental Dynamic Analysis (IDA) was conducted to plot the IDA curves. The maximum value of inter-story drift was selected as the demand parameter and the capacity is determined according to the HAZUS-MH limit states; and finally, the corresponding fragility curves were developed. The results of the 3D nonlinear dynamic analysis indicated that the damage state of the structure due to soft story irregularity was decreased with increasing stories. On the other hand, the damage caused by torsional irregularity in plan was increased by increasing the height of the structure. For example, in the 3-story structure, soft-story effect on damage probability was more dominant than torsional irregularity.

Development and validation of a metamemory maturity questionnaire in the context of English as a foreign language

To determine the inherent components of language learners’ capacity for metamemory maturity, the researchers drafted a metamemory maturity (MMM) questionnaire based on Hultsch et al.’s (Memory self-knowledge and self-efficacy in the aged, Springer-Verlag 65–92, 1988) model. The volunteer participants were a heterogeneous sample of 356 male and female English as a Foreign Language (EFL) teachers and student teachers with various age ranges, teaching experiences, and educational backgrounds. Through a series of factor analytic procedures and structural equation modeling, the final draft of the questionnaire with 30 binary Likert-scale items was validated. Statistics confirmed acceptable measures of internal consistency as well as convergent and discriminant validity. The newly designed MMM questionnaire consisted of three main components of memory strategy use (12 items), memory attentiveness (6 items), memory factual awareness (6 items), and a moderator component of confidence and affect (6 items). The researchers highlight the implications of this questionnaire to provide the teachers with an instrument to analyze the needs of EFL learners for metamemory enhancement strategies.

Research on the Application of Analytic Hierarchy Process in the Multi-target Decision Making of Networked Ammunition

In the process of networked operations, a large amount of target parameter information can be obtained. How to allocate targets to obtain the maximum attack effectiveness of the entire weapon system is of great significance. This paper proposes a multi-objective decision-making method based on analytic hierarchy process. Through the establishment of analytic hierarchy structure model, the construction of comparison judgment matrix, the weight calculation and consistency test of target factors, the calculation of composite weight and the total ranking of levels, etc., finally a reasonable judgment order can be obtained, and the best decision result can be obtained. It provides a reference for the solution of the decision-making problem of multi-point attack, and provides a simple and effective solution for the decision-making of networked ammunition multi-target attack.

Analytical Models of Passive Linear Structures in Printed Circuit Boards

Analytical models for passive linear structures, like metallic traces, vias, are proposed for simulations at the package and Printed circuit board (PCB) levels. In the proposed method, traces are modeled based on the transmission line theory, whereas the vias are described by the parallel-plate impedance and several equivalent circuits elements. The proposed models can be applied to efficiently simulate composed passive linear structures. Several scenarios are analyzed including traces with two or three width, traces routed into different layers and interconnects commonly used in PCBs. The results of the models are compared with those from the fullwave simulations and experiments. An improvement on the computation speed has been observed with respect to the full-wave simulations at the effective range of models. In our measurements, a compensation approach of impedance mismatch in parameter measurements is analyzed and calculated, which could significantly simplify the experimental process.

Dataset from the shake table tests of a rocking podium structure

Conventional validation of analytical and numerical models in Earthquake Engineering involves the comparison of numerically simulated response time histories to experimentally obtained benchmark responses to the same earthquake excitations. As the seismic design problem is inherently stochastic, an alternative, statistical, and easier-to-pass validation procedure has been suggested. As an example, numerical and analytical models may fail to predict the planar rocking response of a rigid block to a specific ground motion, but they can be proven quite successful in predicting the statistical distribution of the maxima of that response to an ensemble of ground motions. This article describes the publicly available data obtained from a series of 226 shake table tests of a 3D rocking podium structure, designed at ETH Zurich and carried out at EQUALS Lab, University of Bristol. This well-documented dataset is the largest one involving a shake table and can be used to statistically validate analytical and numerical models of rocking structures.