Analytical Compliance Research Articles

High-flexibility three-dimensional serial folded hinges

A new three-dimensional flexible hinge capable of large, linear-domain displacements is proposed for extended spatial workspace mechanisms. The hinge structure is compact and modular consisting of a large number of circular- and straight-axis segments connected in series and disposed in two parallel planes in a folded manner. The analytical, linear-model compliance matrix, which is necessary in direct/inverse kinematics and controls analysis, is derived based on simplified hinge geometry and small-deformation theory. The compliance model is accurate, as demonstrated by finite element simulation and experimental testing of a prototype. The compliance model is also utilized to determine the hinge piston-motion stiffness and the static response of several hinges connected in series. Another analytical compliance model is formulated to predict the hinge maximum loads and displacements in terms of allowable stresses. The mathematical models are further utilized to comprehensively investigate the influence of geometric parameters on the hinge performance.

Development of a foam-filled steel web sandwich panel for the rehabilitation of timber floors

Lightweight sandwich panels offer a prominent solution for the rehabilitation of timber floors. This paper addresses the development of a solution capable of continuous production for a foam-filled steel web sandwich panel for floor rehabilitation. The newly designed flooring solution is tested in full-scale quasi-static flexural campaigns. The tests validate the analytical design's compliance with Ultimate limit state (ULS) and Serviceability limit state (SLS) requirements. Furthermore, the flexural behaviour is compared with analytical predictions for thin-walled members according to the effective width method, described in Eurocode 3. Different effective cross-section design assumptions are assessed to allow an accurate prediction of the panel's response.

Modelling and performance analysis of a curvature-adjustable multiple-axis flexure hinge based on Bézier curve

In order to solve the uniqueness of the compliance equations and each notch profile, a curvature-adjustable multiple-axis flexure hinge with complex notch profiles is designed and investigated based on Bézier curve in this paper. The hinge can evolve into multiple-axis flexure hinges with single and hybrid, symmetric and asymmetric notch profiles composed of the ellipse, circle, hyperbola and parabola. In addition, analytical compliance equations in six degrees of freedom based on the Castigliano’s Second Theorem are proposed. Then, a simplified notch profile classification method based on a binary quadratic implicit equation is proposed. Moreover, analytical compliance equations are validated by finite element analysis. The maximum relative error between the finite element analysis and the analytical results is 6.07%. Finally, the compliance, precision of rotation and stress are investigated based on structural parameters. The results show that the change in the rotation centre does not significantly affect the axial and bending compliance for the flexure hinge with a specific single and flush Bézier curve notch profile. Moreover, the flexure hinge with a notch profile consisting of ellipse and hyperbola has the highest rotational precision. The proposed curvature-adjustable multiple-axis flexure hinge can provide more compliance options for the design of compliant mechanisms.

Rapid microwave synthesis of N and S dual-doped carbon quantum dots for natamycin determination based on fluorescence switch-off assay

Green, one-pot, quick, and easily synthesized nitrogen and sulfur co-doped carbon quantum dots (N,S-CDs) were obtained from cheap and readily available chemicals (sucrose, urea, and thiourea) using a microwave-assisted approach in about 4 min and utilized as a turn-off fluorescent sensor for estimation of natamycin (NAT). First, the effect of N and S doping on the microwave-synthesized CDs’ quantum yield was carefully studied. CDs derived from sucrose alone failed to produce a high quantum yield; then, to increase the quantum yield, doping with heteroatoms was carried out using either urea or thiourea. A slight increase in quantum yield was observed upon using thiourea with sucrose, while an obvious enhancement of quantum yield was obtained when urea was used instead of thiourea. Surprisingly, using a combination of urea and thiourea together results in N,S-CDs with the highest quantum yield (53.5%), uniform and small particle size distribution, and extended stability. The fluorescent signal of N,S-CDs was quenched upon addition of NAT due to inner filter effect and static quenching in a manner that allowed for quantitative determination of NAT over a range of 0.5–10.0 μg ml−1 (LOD = 0.10 μg ml−1). The N,S-CDs were applicable for determination of NAT in aqueous humor, eye drops, different environmental water samples, and bread with excellent performance. The selectivity study indicated excellent selectivity of the prepared N,S-CDs toward NAT with little interference from possibly interfering substances. In-silico toxicological evaluation of NAT was conducted to estimate its long-term toxicity and drug-drug interactions. Finally, the preparation of N,S-CDs, and analytical procedure compliance with the green chemistry principles were confirmed by two greenness assessment tools.

A Compact Three-Dimensional Two-Layer Flexible Hinge

The paper proposes a new three-dimensional flexible hinge formed of several serially linked straight- and circular-axis segments that are disposed of in two layers. The novel hinge configuration is capable of large displacements and can be implemented in precision-compliant mechanisms that need to cover large spatial workspaces. Based on simplified geometry, an analytical compliance model is formulated that connects the loads to the displacements at one end of the hinge. Finite element simulation and experimental prototype testing of actual-geometry hinge configurations confirm the analytical model predictions. A related compliance-based analytical model evaluates the maximum loads that can be applied to the hinge and the resulting displacements. The two small-deformation analytical models are subsequently utilized to investigate the relationship between geometric parameters and the hinge performance qualifiers.

Damped two-axis axially collocated flexure hinge.

Broadband motion control in flexure-based stages can benefit from passive damping enhancement at their flexible structures. This paper develops a damped two-axis axially collocated (2-AC) flexure hinge with damping-enabling hybrid inserts and analytically derives its loss factor model based on hybrid (empirical and analytical) compliance modeling and shearing damping modeling. The analytical loss factor model is verified by finite element analysis. It is seen that the geometric parameters of the diameter and slope angle of the insert are sensitive to the hinge's loss factor based on the theoretical loss factor model, especially in low-frequency and resonant zone. The actual experiments and finite element simulation indicate that embedding the hybrid inserts into the 2-AC flexure hinge can improve the damping performance of the hinge.

Characteristics of Statically Indeterminate Symmetric Flexure Structures

Statically indeterminate symmetric (SIS) flexure structures are symmetric structures with “clamped-clamped” boundary conditions. The static indeterminacy and topological symmetry significantly attenuate the parasitic motions associated with statically determinate flexure structures. Hence, SIS flexure structures feature decoupled linear and angular motions, improved motion accuracy, high stiffness, and high stability. Although SIS flexure structures have been more frequently utilized as prismatic joints, they can also be utilized as revolute joints. This study systematically investigates the characteristics of SIS flexure structures. Based on the unified compliance models of a single flexure hinge, analytical compliance models of two fundamental types of SIS flexure structures are established. In 1-degree-of-freedom or planar applications, multiple SIS-based structures can also be integrated into various configurations to transmit linear or angular motions. Corresponding stiffness models are also established. The characteristics and possible applications of the SIS flexure structures are computationally investigated through case studies. Ultimately, several SIS prototypes are manufactured, and the modeling accuracy of the established stiffness models is experimentally verified.

Development of a generalised creep-recovery test and a back-calculation method for determining the permanent deformation of asphalt mixtures in the time domain

The measured strain during a creep-recovery (CR) test comprises both reversible and irreversible strains; therefore, adequate treatment is required to accurately separate them. In this paper, a generalised version of the CR test was proposed to investigate the permanent deformation behaviour of asphalt mixtures exerted by a variety of loading patterns in the time domain. The companion back-calculation algorithm was also proposed to separate with improved accuracy and repeatability the pure viscoelastic (VE) and viscoplastic (VP) strains. First, the creep compliance (CC) was back-calculated based only on the recovery data by using an approximate analytical creep compliance function of the Huet-Sayegh model as the solution function in the optimisation process. Then, the pure VE and VP strains were determined. The results show that the proposed method attains a good level of reliability although relatively short durations of the recovery period have been used.

Vertical frequency‐domain compliance of an elastic pipe pile embedded in a liquid‐filled and porous‐viscoelastic soil

AbstractThe analytical dynamic compliance of an elastic pipe pile fully buried in a fluid‐filled and porous‐viscoelastic soil stratum resting on rigid bedrock and subjected to a vertical time‐harmonic load is proposed. In this study, the Hamilton's principle of dynamics is employed to establish the governing equations for the pipe pile, which is treated as a two‐dimensional (2D) hollow bar structure. The outer and inner soil media surrounding the pipe pile are considered as three‐dimensional (3D), homogenous, and liquid‐saturated porous continuum, besides they are described by the porous‐elastic media model proposed by de Boer. The governing equations for the pipe pile and the soils are solved with the aid of the separation technique of variables, and also utilizing the boundary and contact conditions of the pipe pile and the soils. Then, the analytical solution for the vertical dynamic compliance of the pipe pile is derived. By comparing with the existing solutions and finite element model (FEM), the results from the newly proposed method confirm its validation. Comparative analyses of numerical examples are finally conducted to reveal the variations and response principle of the dynamic compliance of the pipe pile under different material/geometry parameters.

Parametric joint compliance analysis of a 3-UPU parallel robot

Sufficiently low compliance is required for robot end-effectors to perform various tasks with high static and dynamic accuracy. The joint compliance and link compliance of robots are the two major factors for the determination of overall end-effector compliance. Unlike serial robots that can allow larger joint sizes to improve the joint compliance, the joints of parallel robots are usually closely located and hence the joint size cannot be easily increased. Compared with the link compliance, the joint compliance of a parallel robot contributes more to the end-effector compliance, but its importance is often overlooked. To reduce the computational intensity of robot compliance design, analytical joint compliance models are proposed for the class of 3-UPU parallel robots. These joint compliance models can be used to quickly evaluate the compliance contribution of each revolute joint at various parallel robot configurations. Numerical and experimental verifications are provided to demonstrate these models. We expect that the parametric analysis of 3-UPU parallel robot compliance can be facilitated by using the proposed joint compliance models.

Analytical Compliance Equations of Generalized Elliptical-Arc-Beam Spherical Flexure Hinges for 3D Elliptical Vibration-Assisted Cutting Mechanisms.

Elliptical vibration-assisted cutting technology has been widely applied in complicated functional micro-structured surface texturing. Elliptical-arc-beam spherical flexure hinges have promising applications in the design of 3D elliptical vibration-assisted cutting mechanisms due to their high motion accuracy and large motion ranges. Analytical compliance matrix formulation of flexure hinges is the basis for achieving high-precision positioning performance of these mechanisms, but few studies focus on this topic. In this paper, analytical compliance equations of spatial elliptic-arc-beam spherical flexure hinges are derived, offering a convenient tool for analysis at early stages of mechanism design. The mechanical model of a generalized flexure hinge is firstly established based on Castigliano’s Second Theorem. By introducing the eccentric angle as the integral variable, the compliance matrix of the elliptical-arc-beam spherical flexure hinge is formulated. Finite element analysis is carried out to verify the accuracy of the derived analytical compliance matrix. The compliance factors calculated by the analytical equations agree well with those solved in the finite element analysis for the maximum error; average relative error and relative standard deviation are 8.25%, 1.83% and 1.78%, respectively. This work lays the foundations for the design and modeling of 3D elliptical vibration-assisted cutting mechanisms based on elliptical-arc-beam spherical flexure hinges.

«ПЕРША ШПАЛЬТА». ПОРЯДОК ДЕННИЙ МЕДІА МІЖ І ТА ІІ ТУРАМИ ПРЕЗИДЕНТСЬКОЇ КАМПАНІЇ 2019 Р. (НА ПРИКЛАДІ ДОСЛІДЖЕННЯ МАТЕРІАЛІВ САЙТУ ВИДАННЯ «ДЗЕРКАЛО ТИЖНЯ. УКРАЇНА»)

Lomeyko V. I. «The front page». Media agendabetween I and II rounds of the 2019 presidentialcampaign (the example of the research of materials of anonline edition «Mirror of the Week. Ukraine»). – Article.The article is devoted to defining the main topics ofthe political agenda in the analytical materials of thenewspaper «Mirror of the Week. Ukraine» between thefirst and the second rounds of the 2019 presidentialelections in Ukraine. Agenda-setting theory is based onthe fact that the media influence politics by constructingan agenda, i.e. determine the hierarchy of sociallysignificant issues. In Ukraine, the media is always an echoof clan, oligarchic interests. To date, there is no researchto determine the level of influence of individual mediaon the political agenda, i.e. their political «influence».This research is one of the first attempts to outline therange of media that build the agenda in Ukraine. At thepreparatory stage of the study, the publications thatАктуальні проблеми філософії та соціології 107influence the agenda in Ukraine have been identified:«Ukrayinska Pravda», «Mirror of the Week. Ukraine»,«Focus», «NV», «Ukrainian Week», «Day», etc. In orderto determine the unique topics that are inherent in themedia in the construction of the agenda, the publication«Mirror of the Week. Ukraine» has been chosen. In 2019,«Mirror of the Week. Ukraine» won the championship interms of its impact on business and political leaders, thequality of analytical information and compliance withprofessional standards. This weekly publication has beenchosen for the research. The sample was formed by fourissues between the first and second rounds (from 31 Marchto 21 April) of the 2019 presidential elections. Accordingto the results of the study, it has been determined that thepolitical agenda in the media is characterized by a gradualchange of the main topics: from the results of the firstround and the chances of the victory of two candidates(P. Poroshenko and V. Zelensky) and the reasons forthe defeats of others (first of all, Y. Tymoshenko andYu. Boyko) to the identification of socially importanttopics for further political development. The medianot only cover certain events (M. Stepanov’s resignation,A. Avakov’s position, statements of Westernpartners, the case of Privatbank, etc.), but also outlinethe directions of the next President’s actions. Theagenda is formed around the following topics: securityand territorial integrity, P. Poroshenko’s mistakes(personnel ones, as well as the corruption and the failureof judicial reform), the problem of «Privatbank»,the need for reforms and specific proposals for theirimplementation in energy, road construction; landreform, labor migration and early parliamentaryelections. The uniqueness of the agenda in the media isdue to the fact that in each issue journalists and expertssystematically address the topic of social responsibility.This applies not so much to a specific electoral choice,but also to further reforms. It is the themes of socialresponsibility, social defects and pathologies, the lackof solidarity, the need to resist fakes and distinguishbetween the real and the imagined (S. Rahmanin) thatare the foundation of the media agenda. They ensureits uniqueness compared to the agenda of politicians,government officials and oligarchs.

Embracing healthcare delivery challenges during a pandemic. review from a nodal designated COVID-19 center in qatar

Hospitals and healthcare systems are instrumental in the formulation and delivery of a coordinated response to disaster management especially epidemics. In healthcare policy and strategy formation, there are only trade-offs, which with uncertainty are akin to gambles. National organizations play a key role in pandemics through the expression of physician motivation. Effective strategies can facilitate physician action through economies of scale that lower the costs for physicians to meet both community and patients' needs. Moreover, no matter how well clinicians are motivated and positioned to act, their collective actions are likely to fall short without complementary systems for population-based care that require the operational support of an organization. This review of institutional policy implementation and frameworks intends to highlight how a nodal-designated COVID-19 center in Qatar managed to control the menace by altering its procedural sets and work arrangements to augment an integrated, intrinsic response to a briskly emerging, conceivably complex situation. This outcome was achieved under the guidance of a national leadership team, effectively adapted to its specific challenges by building on current medical evidence, management routines, proficiencies, and health system capacity. This ambitious drive started with the cohesion of services and implementation of evidence-based protocols by assigning a physician-led team to research, strategize and organize improved patient flow and information by arranging analytical compliance and preparedness. Through these service approaches and ongoing efforts, HMGH has realized significant outcome improvements, such as increasing capacity building, reducing healthcare waste, and increasing patient satisfaction rates whilst successfully achieving significantly lower COVID-19 mortality both in terms of absolute numbers and as percent population compared to many developed countries in the world. The strategies outlined in this article might not be all-inclusive or fit other healthcare system models, but they generate a veritable interest to pursue and be subjected to further rigorous study.

Tripod mechanisms with novel spatial Cartesian flexible hinges

The paper studies the tripod mechanisms that comprise novel spatial Cartesian flexible hinges and can be used in three-dimensional sensing/actuation applications. These hinges are formed of serially-connected straight- and circular-axis elastic segments that are located in planes parallel to the planes of a Cartesian reference frame. Two spatial flexible hinge designs are proposed and their compliance matrices are derived based on closed-form compliances of the basic segments. The hinge compliance matrices are utilized to formulate the stiffness matrix of tripod mechanisms that are parallel combinations of three identical hinges and a rigid link. The hinge analytical compliance model is confirmed through finite element code simulation while the tripod analytical stiffness is verified by both finite element analysis and experimental testing of fabricated specimens. Comprehensive simulation is subsequently performed to study the influence of the geometric parameter values on the hinge and tripod analytical compliance/stiffness.

New series and parallel 3D Cartesian right circularly corner-filleted flexible hinges

This work introduces a three-dimensional (3D) right circularly corner-filleted flexible hinge composed of four planar segments that are serially connected and located in two planes of the global Cartesian frame. The 3D hinge configuration realizes full load-displacement coupling in terms of the six degrees of freedom (DOF) at its free end, enhancing thus the motion capability, range and versatility. A linear analytical compliance model is developed to describe the load-deformation behavior of this hinge using matrix formulation. Thorough finite element simulation confirms the analytical model results. A comprehensive study is performed based on the analytical model to identify the influence of the hinge geometric parameters on its deformation response. A parallel-connection hinge is also introduced, which consists of three identical 3D Cartesian hinges joined to a rigid link and resulting in a tripod stage. A prototype stage is manufactured and experimentally tested whose results validate the analytical model predictions. Further analysis studies the static regular and parasitic behavior of the stage in terms of its defining geometry.

Closed-form compliance equations for elliptic-revolute notch type multiple-axis flexure hinges

This paper presents the closed-form compliance equations of elliptic-revolute notch type multiple-axis flexure hinges undergoing small displacement for three-dimensional applications. Analytical compliance equations in six degrees of freedom are explicitly derived based on the beam theory. Comparisons with existing compliance equations of revolute flexure hinges are carried out. The presented compliance equations for the elliptic-revolute flexure hinges can result in the compliance equations for the cylindrical- and circular-revolute flexure hinges. Finite element analyses are performed to verify the developed equations. Numerical simulation is conducted to test the compliance characteristics of the elliptic-revolute flexure hinges. The simplified coefficients between the compliances of the elliptic- and circular-revolute flexure hinges are established. The presented compliance equations are helpful for designing spatial compliant mechanisms based on the elliptic-revolute flexure hinges.

Crack length correction and root rotation angle in a sandwich single cantilever beam (SCB) fracture specimen

Crack root rotation is a measure of deviation from clamped boundary conditions of region in front of the crack tip. The root rotation depends on the shear force and bending moment acting at the crack tip. Such rotation significantly affects the compliance and energy-release rate. Crack root rotation analysis of Single Cantilever Beam (SCB) sandwich specimens is presented here. Closed-form solutions for the root rotation angle obtained from the foundation analysis are compared to finite element analysis (FEA) predictions. The derived expressions closely match for a range of sandwich configurations. An expression for the energy-release rate, derived from the foundation analysis was found to agree with FEA predictions over a large range of face-to-core modulus ratios. Energy-release rate and mode mixity phase angle increased with decreasing crack length due to the transverse shear effects. At longer crack lengths, both energy-release rate and phase angle reached a value independent of crack length. The foundation model is used to derive a simple expression for the offset crack length for the SCB sandwich fracture test. It is shown that the obtained formulation agrees closely well with both numerical and experimental values. In addition, SCB fracture tests performed using an in-house built translatable rig showed close relation to both analytical and numerical compliance results.

Analytical Compliance Model for Right Circle Flexure Hinge Considering the Stress Concentration Effect

In this paper, an analytical compliance model for right circle flexure hinge (RCFH) is presented with the stress concentration in consideration. The stress concentration caused by changes in RCFH’s cross-section usually happens at the weakest point. It has been shown to seriously affect RCFH’s compliance calculation. Based on the virtual work theory, superposition relationship of the deformation, as well as Castigliano’s second theorem, RCFH’s analytical compliance model considering the stress concentration effect is established. The model is calculated as a series of closed-form equations which are related with geometric dimensions and employed material. Complicated definite integrals existing in these compliance equations are proved to be correctly calculated through comparisons with other literatures. Finally, in order to examine the validity of the established model, finite element analysis (FEA) is conducted. The relative errors between the theoretical values obtained by the established model and FEA results are found within 20% for a wide range of geometric dimensions.

Drinking water quality: results from the data analysis in Lombardy region

Abstract Background Ensuring access to safe and quality drinking water is an essential aspect of public health, as well as a fundamental human right as an extension of the right to life affirmed by the Universal Declaration of Human Rights. Previously in Lombardy, the reporting of water sampling control activities was prepared only by the local health authorities (LHAs). Recently, however, the activation of a data centralization information system allows the monitoring of the whole regional territory and the elaboration of a periodic report. Methods The data relating to the analytical checks on drinking water in the Lombardy Region were extracted from the regional database for 2014, 2015 and 2016 and grouped by ’Chemical’, ’Microbiological’ and ’Indicators’ parameters. The analysis focused on the number and analytical compliance of all the samples performed. All the results considered both the overall regional data and each LHA. Results From a quantitative point of view, the activity of entering the sampling data seems to progressively improve, remaining rather heterogeneous among the various LHAs. From a qualitative point of view drinking water in Lombardy is to be considered good overall: both the chemical and microbiological non-compliant samples in Lombardy are lower than 10% for the years 2014 and 2015 and lower than 5% in 2016 thus indicating an apparently improving trend. Conclusions For a better evaluation of the numerical appropriateness of the controls carried out, an update of the registry system of the supply areas and a more uniform LHA programming is necessary. For a better assessment of the quality of water destined for human consumption oriented to the conformity of parameters, it is necessary to adopt an analytical judgment system on individual parameters instead of on the entire sample. A further improvement will be the inclusion in the database of the data of the aqueduct managers included in the Water Safety Plans (WSPs). Key messages Water quality assessment and its control activity reporting is an essential aspect in public health prevention. It is essential to strive for continuous improvement in the data collection method to better monitor potential risks and to evaluate the best future safe water supply strategies.

Straight-axis folded flexure hinges: In-plane elastic response

This research generalizes the serpentine hinge design and concept by studying the straight-axis folded flexure hinge as a large-displacement counterpart of shape-similar, solid notch hinges. A folded hinge is formed of several unit segments that repeat periodically along the axial direction and are inscribed in a region defined by various geometric envelope curves. The envelope curves are identical to the curves defining the outer profile of the parent solid flexure hinges. This concept increases the number of design parameters of a solid notch hinge by including the geometry and dimensions of the envelope curve, the number of unit segments, the distance between segments, and the geometric configuration of each segment. Two categories of folded hinges are studied here: one category is defined by a rectangular envelope with all unit segments being identical; the other category uses curved-line envelopes and the unit segments scale along the transverse direction. For both categories generic in-plane analytical compliance models are formulated. A particular design is analyzed from each category with the unit segment serially combining straight- and elliptic-line portions. The validity of the analytical compliance model is verified by means of experimental testing and finite element analysis of some simple translation stages that include either rectangular- or circular-envelope folded hinges. The analytical compliance model is subsequently utilized to assess the quasi-static response sensitivity of the folded hinges to the geometric parameters, and to compare the folded configurations with their parent, notch designs.