Hinge Mechanism Research Articles

Preparation of novel silver borates by soft hydrothermal synthesis in sealed tubes: New representatives of larderellite and veatchite families

New silver-based representatives of the larderellite and veatchite families, Ag2B10O14(OH)4∙H2O (1) and Ag2B5O8(OH)∙H2O (2) respectively, have been prepared using a soft hydrothermal synthetic approach inside a sealed silica tube. Both structures are built of the pentaborate groups yet exhibit various dimensionality: 2D for 1 and 1D for 2. The silver atoms in 1 exhibit noticeable anharmonicity approximated using Gram–Charlie approach. 1 was additionally characterized by thermal analysis, high-temperature X-ray powder diffraction and IR spectroscopy. Thermal expansion of 1 is strongly anisotropic (α11 = 38, α22 = −13, α33 = 14 × 10−6 °С−1) which is related with the hinge mechanism of the larderellite chains from corner-sharing pentaborate groups. Topology and complexity analysis of these compounds within the larderellite and veatchite families is presented.

Deep generative models of LDLR protein structure to predict variant pathogenicity

The complex structure and function of low density lipoprotein receptor (LDLR) makes classification of protein-coding missense variants challenging. Deep generative models, including Evolutionary model of Variant Effect (EVE), Evolutionary Scale Modeling (ESM), and AlphaFold 2 (AF2), have enabled significant progress in the prediction of protein structure and function. ESM and EVE directly estimate the likelihood of a variant sequence but are purely data-driven and challenging to interpret. AF2 predicts LDLR structures, but variant effects are explicitly modeled by estimating changes in stability. We tested the effectiveness of these models for predicting variant pathogenicity compared to established methods. AF2 produced two distinct conformations based on a novel hinge mechanism. Within ESM’s hidden space, benign and pathogenic variants had different distributions. In EVE, these distributions were similar. EVE and ESM were comparable to Polyphen-2, SIFT, REVEL, and Primate AI for predicting binary classifications in ClinVar. However, they were more strongly correlated with experimental measures of LDL uptake. AF2 poorly performed in these tasks. Using the UK Biobank to compare association with clinical phenotypes, ESM and EVE were more strongly associated with serum LDL-C than Polyphen-2. ESM was able to identify variants with more extreme LDL-C levels than EVE and had a significantly stronger association with atherosclerotic cardiovascular disease. In conclusion, AF2 predicted LDLR structures do not accurately model variant pathogenicity. ESM and EVE are competitive with prior scoring methods for prediction based on binary classifications in ClinVar but are superior based on correlations with experimental assays and clinical phenotypes.

What is a Hinge Mechanism? What did Kempe Prove?

What is a Hinge Mechanism? What did Kempe Prove?

Shaking table test on irregular and complex connected structure

Affected by the external environment, it is easy to cause complex and irregular problems in the building structure, bringing new safety hazards to the seismic resistance of the structure. Based on the background of the east building of the railway station with cross ground crack, the seismic performance of irregular and complex connected structures under different seismic intensities was analysed.The research results indicate that under the action of a 7-degree seismic fortification, the structure is basically in an elastic state, with a stiffness degradation of 12.9%, meeting the performance requirements of being undamaged during small earthquakes; Under seismic fortification, the structure is mainly characterized by cracking at the bottom beam end, with a small crack width and a stiffness degradation of 41.7%, meeting the requirements for moderate earthquake repairability; Under the rare earthquake of 8degree , plastic hinges begin to form at the beam and column ends of the structure and gradually develop, with stiffness degradation reaching 81.9%. All seismic responses of the structure comply with the limit requirements of the code (GB 50011-2010); Under the rare earthquake of 8 degree , there is a serious torsion phenomenon in the small triangle area, which leads to the disharmony of forces on the inner and outer beams and columns. In earthquakes, it is easy to cause structural collapse due to the first failure of the outer columns. Suggesting to increasethe stiffness of the small triangular column to solve the above problem. Under extremely rare earthquakes, the plastic hinge mechanism of the structure has developed completely, with stiffness degradation approaching 90% and no collapse phenomenon, indicating that complex connected structures have excellent seismic performance.

Neurofilaments - Small proteins of physiological significance and predictive power for future neurodegeneration and cognitive decline across the life span.

Neurofilaments (NFs) are not only important for axonal integrity and nerve conduction in large myelinated axons but they are also thought to be crucial for receptor and synaptic functioning. Therefore, NFs may play a critical role in cognitive functions, as cognitive processes are known to depend on synaptic integrity and are modulated by dopaminergic signaling. Here, we present a theory-driven interdisciplinary approach that NFs may link inflammation, neurodegeneration, and cognitive functions. We base our hypothesis on a wealth of evidence suggesting a causal link between inflammation and neurodegeneration and between these two and cognitive decline (see Fig. 1), also taking dopaminergic signaling into account. We conclude that NFs may not only serve as biomarkers for inflammatory, neurodegenerative, and cognitive processes but also represent a potential mechanical hinge between them, moreover, they may even have predictive power regarding future cognitive decline. In addition, we advocate the use of both NFs and MRI parameters, as their synthesis offers the opportunity to individualize medical treatment by providing a comprehensive view of underlying disease activity in neurological diseases. Since our society will become significantly older in the upcoming years and decades, maintaining cognitive functions and healthy aging will play an important role. Thanks to technological advances in recent decades, NFs could serve as a rapid, noninvasive, and relatively inexpensive early warning system to identify individuals at increased risk for cognitive decline and could facilitate the management of cognitive dysfunctions across the lifespan.

Plastic hinge and damage mechanism of RC assembly column base joint with post pouring area

Column base joint with post pouring area connected by grouted sleeves (PPCGS), which can solve the problems of poor controllability of grouting quality in the engineering application of traditional sleeves, is proposed in this paper. Based on the horizontal low-cycle reversed loading test results of six full-scale column base joints under axial pressure, the mechanics characteristic of plastic hinge, the length of equivalent plastic hinge, and the displacement ductility are mainly explored. The research results showed that the plastic hinge was formed above the sleeves in all precast column base joints, and the post pouring area of PPCGS column base joints can provide higher compressive strength, so it could protect the longitudinal rebar under the sleeve from premature buckling deformation, made the plastic hinge fully develop at the top of the sleeves. The ratio of the equivalent plastic hinge length to the section size of PPCGS column base joints decreases as the section size of column and the strength of the post pouring material increase. The average error between the calculated results and the test results of the displacement ductility coefficient of PPCGS column base joints is -3.93%, and the displacement ductility coefficient showed an increasing trend with the increase of the section size and the strength of post pouring material. In addition, a finite element analysis method for the PPCGS column base joint was verified through experimental results, and the influence law of post pouring height and tenon section size on the damage of column base joint was obtained through parametric analysis.

Design and evaluation of a stick-slip piezoelectric actuator with flexure hinge mechanism inspired by the earthworm.

In this work, a new bionic piezoelectric actuator inspired by the earthworm is proposed, fabricated, and tested. The operating principle of the actuator imitates the crawling motion of the earthworm. The piezoelectric stack is embedded in the stator with a flexure hinge mechanism. One side of the stator is inspired by the earthworm body. Then the elongation of the piezoelectric stack is transmitted to the driving tip to produce oblique displacement under such a stator. The vertical and horizontal components are used to press and drive the slider, respectively. The principle of the proposed actuator is described in detail. The static deformation is investigated by the FEM method. A dynamic model of the actuator is developed to further reveal the motion characteristics of the slider via theoretical analysis. Finally, the output characteristics of the proposed BPA are tested. The experimental results show that the actuator achieves a maximum output speed of 12.72 mm/s at a voltage of 100V and a frequency of 710Hz. The maximum output force is 3 N under a locking force of 2 N. Besides, the displacement resolution is tested at 87nm at a frequency of 710Hz, which indicates that the developed actuator can be applied in the field of precision actuation.

Development and Evaluation of a MASH TL-3 Modified Single Wood-Post Skid-Mounted Sign Support System

Previous crash testing determined that the conventional Texas Department of Transportation, U.S., single wood-post, skid-mounted temporary sign support system did not satisfy guidelines included in the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH). Modifications were made to the system to improve impact performance and meet MASH requirements. The modifications included increasing the mounting height of the sign, installing weakening holes in the wood support post at a prescribed height, and adding a wire rope loop around the weakening holes to act as a hinge mechanism when sections of the wood sign support fracture during vehicle impact. Crash tests were performed on the modified system in accordance with the MASH Test Level 3 (TL-3) matrix for work-zone traffic control devices. The modified single wood-post, skid-mounted temporary sign support system with a 90 in. sign mounting height, weakening holes, and tether cable met the performance criteria for MASH TL-3 work-zone traffic control devices.

A Compact Piezo-Inertia Actuator Utilizing the Double-Rocker Flexure Hinge Mechanism.

With a simple structure and control method, the piezo-inertia actuator is a preferred embodiment in the field of microprecision industry. However, most of the previously reported actuators are unable to achieve a high speed, high resolution, and low deviation between positive and reverse velocities at the same time. To achieve a high speed, high resolution, and low deviation, in this paper we present a compact piezo-inertia actuator with a double rocker-type flexure hinge mechanism. The structure and operating principle are discussed in detail. To study the load capacity, voltage characteristics, and frequency characteristics of the actuator, we made a prototype and conducted a series of experiment. The results indicate good linearity in both positive and negative output displacements. The maximum positive and negative velocities are about 10.63 mm/s and 10.12 mm/s, respectively, and the corresponding speed deviation is 4.9%. The positive and negative positioning resolutions are 42.5 nm and 52.5 nm, respectively. In addition, the maximum output force is 220 g. These results show that the designed actuator has a minor speed deviation and good output characteristics.

Ductility and Distribution of Strains on Column Reinforcement Retrofit with Wire Mesh

Abstract A lot of damage to building structures due to earthquakes is damage to column components that serve as vertical elements to pass the load to the foundation. Ductility is one of the parameters that must be owned by the column and as part of the column, longitudinal reinforcement is part of the column element that is quite vital and one of the parameters that can be studied is the distribution of strains that occur in longitudinal reinforcement when burdened with cyclic loads. In this study, a study of the ductility and distribution of strain values occurred in the reinforcement of control columns and retrofit columns with wire mesh size M6. From the test results in can be that on the column that is retrofit with wire mesh and SCC experienced an increase in the value of ductility. While the strain value on the reinforcement of the control column and retrofit column tends to enlarge when it is in the plastic hinge area of the column. In the control column the strain value that occurs in the plastic hinge area is greater than the strain value in the retrofit column, so that in the control column the plastic hinge mechanism has begun to form, while in the retrofit column the plastic hinge mechanism has not been formed due to higher stiffness.

Structural behaviour of 2D post-tensioned precast beam-column sub-assemblages subjected to column loss scenario

Many previous studies have investigated alternative load path (ALP) mechanisms of 2D reinforced concrete (RC) beam-column sub-assemblages under column removal scenarios. However, how precast and prestressed RC structures respond under a column loss scenario receives far less attention, as evident from a lack of published test data. Herein, five 2D post-tensioned precast RC sub-structures subjected to a middle column loss scenario were tested by multi-point quasi-static loading. In all the specimens, individual precast members such as beams and columns were joined together through wet connection. The study focused on investigating the combined effects of post-tensioned tendon (PT) and wet connection on load-resisting mechanisms and the influence of basic parameters such as unbonded and bonded PT, T-beam effect, and boundary conditions. The test results indicated that both unbonded and bonded parabolic-shaped PT significantly enhanced compressive arch action (CAA) and catenary action (CA) beyond basic flexural capacity, and also changed the plastic hinge mechanism in the precast beams. The specimen with unbonded PT could provide greater residual capacity than bonded PT, but the former was severely damaged by fracture of normal reinforcement and crushing of concrete rather than fracture of the tendon. In addition, the effects of T-beam and boundary conditions are discussed in detail. Finally, new design criteria for precast and post-tensioned concrete structures under column removal scenarios are proposed for structural engineers to take advantage of high-strength tendons and avoid failure at critical locations by precast joints.

Experimental study on PSPC beam – Concrete encased CFST column frame installed with novel steel panel dampers

A concrete-filled steel tubular (CFST) column has a bearing capacity with a relatively small cross section. From the perspective of the assembly, a partially steel-reinforced precast concrete (PSPC) beam can combine the merits of both the reinforced concrete beam and steel beam. However, strong earthquake action puts forwards a dramatic seismic requirement for the high-rise frame. In this study, to improve the seismic performance of the structure in an economical way, the duplex assembled I-shaped steel panel damper (DAISPD) was introduced to the PSPC beam-concrete encased CFST column frame through the eccentric brace. A half-scaled two-storey two-bay substructure specimen was tested under cyclic loading. A series of seismic properties was then analysed, including the failure modes, hysteretic performance, and energy dissipation capacity. To further investigate the contribution of the damper, groups of numerical analyses were conducted on the key design parameters of the DAISPD. The introduction of the damper provides an adequate lateral stiffness and energy absorption to the frame, especially when the interstorey drift is within the elastic and plastic drift limits. The damage of the damper and the beam hinge mechanism occurs sequentially, which results in a two-stage failure mode. Considering the predamage contribution and the postdamage influence of the damper, it is recommended to design with a moderate yield force and a small height.

Design of a Flexible Hinged Piezoelectric Viscous Slip Actuator with Retraction Suppression

In order to solve the displacement regression phenomenon of piezoelectric viscous-slip actuators, this paper proposes a lever-type flexible hinge mechanism that uses two sets of piezoelectric stacks to move the slider in both directions and efficiently suppress the displacement regression phenomenon. First, the overall dimensional parameters of the drive are designed, the device is modeled using 3D software, and the driving principle is analyzed. Then a theoretical model is built based on the lever amplification principle to derive the relevant expressions for the piezoelectric viscous slip actuator under sawtooth wave type voltage signals. The piezoelectric stack is simulated and analyzed with COMSOL Multiphysics to obtain the modal and stress-displacement clouds of the flexible hinges. Finally, a prototype was built for experimental testing, and the slider in the device was able to achieve smooth motion and effectively suppress the displacement regression phenomenon. The input voltage of piezo stack A is 100 V, the input voltage of piezo stack D is 150 V, the input frequency is 212 Hz, the maximum output displacement of single-step drive is 46.6 μm, and the amplification ratio of flexible hinge input to output is 2.59. The piezoelectric viscous-slip actuator was verified to be able to achieve effective drive and suppress back-off.

A Novel Piezo Inertia Actuator Utilizing the Transverse Motion of Two Parallel Leaf-Springs.

A novel linear piezo inertia actuator based on the transverse motion principle is proposed. Under the action of the transverse motion of two parallel leaf-springs, the designed piezo inertia actuator can achieve great stroke movements at a fairly high speed. The presented actuator includes a rectangle flexure hinge mechanism (RFHM) with two parallel leaf-springs, a piezo-stack, a base, and a stage. The mechanism construction and operating principle of the piezo inertia actuator are discussed, respectively. To obtain the proper geometry of the RFHM, we have used a commercial finite element program COMSOL. To investigate the output characteristics of the actuator, the relevant experiment tests including loading capacity, voltage characteristic, and frequency characteristic are adopted. The maximum movement speed and the minimum step size are 27.077 mm/s and 32.5 nm, respectively, confirming that the RFHM with two parallel leaf-springs can be used to design a piezo inertia actuator with a high speed and accuracy. Therefore, this actuator can be used in applications with fast positioning and high accuracy.

Design and Optimization of a Hinged Mechanism Guiding Flap to Three Positions

The design of high-lift devices for commercial aircraft is a multidisciplinary problem. One of the difficulties is that the mechanism is difficult to accurately guide the flap to the aerodynamic design position. Therefore, the traditional high-lift device often adopts a complex mechanism, which brings the disadvantages of high structure weight and low reliability. The hinge flap composed of pure rods improves these disadvantages with a small loss of aerodynamic performance. In this paper, a new type of hinge flap mechanism that can meet the needs of three-position design is studied. First, the calculation method of the mechanism parameters and the kinematics simulation are introduced. The guiding position of the mechanism is basically consistent with the aerodynamic design position, and the maximum error is less than 0.1 mm. Then, the mechanism parameters are optimized, including two aspects. The fairing size and the tangential load of the mechanism are optimized for the support part, and the inboard and outboard rotary actuators are optimized to maintain a linear relationship as much as possible with a maximum deviation of no more than 0.058 deg. Finally, the aerodynamic performance of the takeoff and landing configurations guided by the mechanism is evaluated.

Theoretical justification of the parameters fle­xible screw conveyor for transportation of grain materials

Goal. Increasing the efficiency of the functioning of flexible screw conveyors by substantiating the parameters of the improved design of the articulated and sectional working body for transporting loose agricultural materials. Methods. Theoretical studies were carried out using the methods of theoretical mechanics and higher mathematics. Theoretical calculations of the obtained analytical dependencies and construction of graphical dependencies were performed on a PC using developed programs in the Delphi and SolidWorks software environments. Results. To ensure the correct functioning of the hinge assembly, a study of its design parameters was carried out, which provides mutual rotation, the necessary angular displacement of the axes and the absence of jamming. An analytical relationship is derived for determining the arc movement of the ball along both friction surfaces, the speed of movement of each ball along the arc of the spherical sleeve, and the coefficient of practical action of the hinge and the torque on the drive shaft. Based on the obtained theoretical dependencies, a Pascal program was created in the Delphi environment, and calculations and analysis of the change in the efficiency of the hinge mechanism were performed depending on the main design parameters: the ratio of the radii of the ball and the cylindrical sleeve at the point of contact, the angle of deviation of the hinge axes, the angle of the conical surface holes To choose rational design parameters of the sections of the screw working body, computer modelling of the influence of power loads on the corresponding deformations depending on their operating conditions was carried out. Conclusions. It was established that the transmission efficiency ratio has a maximum value within the range of 0.89...0.93 at a radius ratio of 0.2...0.4. To determine the working area of a particular joint, it is necessary to use design parameters in which the value of the coefficient of practical action is not less than 0.9. The calculation shows that increasing the angle of the hole’s cone reduces the mechanism’s efficiency. It is advisable to choose the ratio of the radii of the ball and the cylindrical sleeve as large as possible for constructive reasons, not less than 0.3. The angle of inclination of the conical surface of the hole should be chosen as minimally as possible, taking into account the selected design scheme of the hinge. In the case of using long conveying screws with a significant number of elements, it is advisable to reduce the angles of deviation of the axes (increase the bending radius of the screw) to improve the overall efficiency of the entire conveyor. A sharp bend in the pipe of the working body, even in one place, can lead to jamming the whole mechanism.

Development of Double-Insulated Ring Sensors for Hollow Pin Preload Measurement

The hinge mechanism of aviation flap is composed of joint bearing, single lug, double lugs, hollow pins and self-locking nuts, etc. This hinge mechanism has accurate requirements for the preload of the hollow pin. When no seizure of the joint bearing occurs, the bolts are required to have sufficient preload to clamp the inner ring of the bearing. Meanwhile, when the seizure of the joint bearing occurs, there shall be no movement between the bearing and pin shaft or the end face of the bushing shall arise. This requires that the tension of the hollow pin shaft shall not be too high, otherwise the friction torque isn’t easy to overcome. However, the method to directly measure the preload in the hollow pin is not available, and the influence law of preload decline on the seizure resistance of the bearings also can’t be evaluated. This paper presents a method suitable for measuring the preload of hollow thin-walled pin parts. By applying permanent piezoelectric thin film transducer onto the end face of the hollow pin, the standardization technology is used to measure the propagation time change of the ultrasonic signal generated by the transducer in the pin as a function of the temperature and preload, thus realizing the accurate measurement for the preload of the hollow pin during installation. Finally, the application verification is conducted by using the measurement method proposed in this paper. The results show that this method can effectively optimize the installation and service performance for the hollow pin.

Fatigue damage stiffness degradation modeling of right circular flexure hinges

Flexure hinges are susceptible to fatigue damage under cyclic loading, resulting in performance degradation. This paper investigates the stiffness degradation of the right circular flexure hinges (RCFHs) under cyclic loading. Fatigue damage experiments are conducted to obtain the stiffness degradation curves, which can be divided into several stages by feature points. A relationship between feature lives and alternating stress amplitudes is established. A fatigue damage stiffness degradation piecewise curve model for RCFHs is proposed. The effect of notch stress concentration on fatigue damage is analyzed. Fatigue damage experiments under non-zero mean stress are conducted, and an equivalent fatigue stress equation is obtained. Finally, a generalized fatigue damage stiffness degradation model for RCFHs is developed, which establishes a relationship between residual stiffness and cycle number. On this basis, a fatigue damage performance modeling method for flexure hinge mechanisms is proposed. The fatigue damage performance of a compliant bridge mechanism was modeled and tested. The experimental results of input stiffness degradation are generally in agreement with the predicted results, which verify the validity of the method.

Redundant Parallel Beam Multiaxis Force Sensor—Stress Correlation Coefficient

The stress nonuniformity on the loading neck is an important factor that leads to the local force error of an individual multiaxis force sensor (MAFS) in a distributed multiaxis force sensing system (DMAFSS). The stress correlation coefficient is used to characterize the stress nonuniformity. The stress correlation coefficient decreases with the increase of the loading offset. A full-constrained high-relative-stiffness-ratio structure is important for an MAFS to obtain a good stress correlation coefficient on its loading neck under various external loads. An individual MAFS with two loading necks is employed in the sensing system to increase the relative stiffness ratio. A thin loading neck, a long loading neck distance, and a high stiffness loading frame are important for the high-relative-stiffness-ratio structure. A local high-relative-stiffness-ratio structure is valuable for a large-scale DMAFSS. The mechanical hinge on the loading neck is useful to realize a large-scale lightweight DMAFSS. The extreme load including the load outside the reference loading zone and the concentrated torque affects the stress correlation coefficient apparently which should be specified in future standards.

Универсальный метод структурного синтеза и построения полного атласа многоконтурных ортогональных структур самоустанавливающихся рычажных механизмов в машиностроении

The paper considers theory and practice of structural synthesis, classification of assembly and construction of a complete atlas of the new class multi-loop mechanisms, where the multi-hinge linkages are made with all hinges positioned on the same line, such mechanisms are called the orthogonal mechanisms. Original universal method is proposed for structural synthesis of these multi-hinge linkage mechanisms with a given large number of independent closed loops in the kinematic chain to create a variety of mechanisms with the given different number of degrees of freedom of their drive. Using this method to create new efficient multilink mechanisms does not require introduction of complex computer programs and consideration of tens of thousands of the Assur groups in order to build complete atlases in closed chains of the parallel structure mechanisms reliably not containing any harmful redundant links. This makes it possible to solve the problem of structural synthesis of the self-adjusting orthogonal mechanisms, including both single and multiple hinged joints of the lever links. Based on the orthogonal structural synthesis proposed algorithm, a complete atlas of 20 non-isomorphic three-circuit orthogonal eight-link basic kinematic chains was constructed for the first time, which formed the basis for synthesizing 27 new schemes of single-moving flat hinged mechanisms with simple hinges. This increases the possible composition of their database to 180 closed structures. Effectiveness of the proposed universal synthesis method is confirmed by examples of inventions of various multi-loop orthogonal self-adjusting lever mechanisms and manipulators of the parallel structure.