Rigid Connection Research Articles

Nonlinear static analysis of cold-formed steel frame with rigid connections

Cold-formed steel (CFS) has become widely popular in mid and low-rise housing owing to efficient construction practice, technical, structural, and economic advantages over conventional structural materials. However, these sections are still not presented in seismic region because of their lack of understanding in seismic response. To address this problem, CFS frames used in residential building were analysed for lateral load capabilities. A finite element analysis of cold-formed steel frames (CFSF) with rigid connections was presented in this research. 72 types of CFS frames made from developed upright sections were simulated for nonlinear static behaviour using a commercial package. A geometrical parametric study on lateral load capabilities with respect to maximum permitted lateral deflection was presented. The performance of frames for lateral load was found to be improved significantly by increasing the thickness of uprights and provision of channel stiffeners.

Bending stiffness variability between a deployable robotic laser osteotome and its insertion device

Abstract Varying device stiffness on purpose can provide safety and performance improvements in interventions involving flexible minimal-invasive surgical robotic devices. For example, when flexible robotic devices are used for inserting minimal-invasive tools along curved paths into the knee joint for arthroscopy, a high device stiffness can allow precise path following where desirable. In contrast, when the minimalinvasive flexible device has reached its desired location inside the patient’s body, decoupling the surgical tool (end-effector) from the flexible robotic insertion device can be beneficial in avoiding transferring disturbances such as vibrations to the robot-patient interaction. In this paper, we investigate bending stiffness variability in dependence on the length of a flexible supply channel. Our experiments have shown that bending stiffness in fact decreases with the length of the supply channel but the highest stiffness connection is not sufficiently rigid and we plan to implement a more rigid connection to allow precise path following during insertion.

Analysis of Initial Rotational Stiffness for Different Section of Semi-Rigid Connection

Structural frames are designed for gravity loads. For rigid connections, the entire 100% intensity of the beam section is not used, this is because the end support moment of the beam at the end is always greater than the midspan moment. The end moment value of the beam is reduced by using a semi-rigid connection. In this paper we have analyzed semi rigid connections for different sections. The results of the study indicatethat the formula in the paper appropriately stated the initial rotational stiffness of the top and seat angle connections. The type of semi-rigid connection is usually chosen based on stiffness of connection. In this paper initial connection stiffness (Rki) of an unstiffened top and set angle with double web angle semi-rigid connection of G+3 steel structure is estimated and result obtained are validated using theLiu Wei and Shu Ganping.

Effect of Semi-Rigid Joints on Design of Steel Structure

Abstract: Limit state design method has presented a new era of safe and economic construction for steel structures. New standard IS 800:2007 for design of steel structures has provided an opportunity for modern design philosophy, design specifications and provisions as per Limit State Method of design in our country. In design of steel structures, steel connections are important elements for controlling behaviour of structure. It is essential that to understand behaviour of steel frame, connectors are required to develop full or a little higher strength compared to members being joined in order to achieve a safe and an economical design. A connection rotates through angle Or caused by applied moment M. This is angle between beam and column from their original position. Several moment-rotation relationships have been derived from experimental studies for modelling semi-rigid connections of steel frames. These relationships vary from linear model to exponential models and are nonlinear in nature. Connections possess semi rigid end conditions in actual behaviour. In the present dissertation, the effect of semi rigid joints on design of steel structures is studied. The behaviour of semi rigid connections and its modelling is discussed. The analysis of the frames is done using ANSYS 2016 and the comparative results of rigid, semi rigid and pinned end conditions has been presented in graphical form. From the results of analysis the design of various semi rigid connections is carried out. Further buckling analysis of stepped columns has been carried out in order to obtain effective length parameters for semi-rigid connections. The design examples has been solved using AISC and IS 800-2007. The comparison is done for fixed, semi rigid and pinned end condition. Keyword: semi-rigid joint, frame analysis, rotational stiffness, buckling length, genetic algorithm.

Analysis of Denture Base Displacement between Conventional Acrylic Removable Partial Dentures and Click Fit Partials for Kennedy\'s Class I and II Situations: An In Vitro Study

The aim of this study was to evaluate the displacement of the denture base of conventional acrylic dentures and Click Fit partials in Kennedy's class I and II situations in the mandibular arch. Four removable partial dentures-two conventional clasp dentures and two attachment dentures (Click Fit)-were designed. The two conventional clasp dentures were retained by C (conventional) clasps, and the two attachment dentures were retained by rigid precision attachments. The displacement of denture bases and the movements of denture bases were investigated, and the influences of denture design were studied. The values obtained were statistically analyzed by using independent t-tests. For all statistical purposes, a p-value of ≤0.001 was considered significant. The results showed that mean vertical displacements (mm) of the conventional acrylic removable partial denture base for Kennedy's class I mandibular arch under 50, 75, and 100 N forces were 0.0317, 0.04377, and 0.06392, respectively, and those for Kennedy's class II mandibular arch under 50, 75, and 100 N forces were 0.04922, 0.09849, and 0.1522, respectively. Vertical displacements (mm) of the Click Fit removable partial denture base for Kennedy's class I mandibular arch under 50, 75, and 100 N forces were 0.02185, 0.03436, and 0.005365, respectively, and those for Kennedy's class II mandibular arch under 50N, 75N, and 100N forces were 0.0445, 0.07851, and 0.14457, respectively. The difference between the groups was statistically significant (p ≤0.001). The vertical displacement of the denture base retained by conventional C clasps was more than that of the denture base retained by rigid precision attachment. The displacement of the denture base tended to be less when the denture was designed with a rigid connection for the retainer and with cross-arch stabilization as in Kennedy's class I case. This research evaluated the vertical denture base displacement using different designs and retention types. Hence, it helped predict the prognosis of different removable partial denture base designs in various clinical conditions.

THE SIEMENS’ “GADABAY POSSESSION” IN TRANSCAUCASIA

The article presents the history of the so-called “Gadabay possession”, which was the allotment of public lands and forests to the Gadabay and Kalakend copper smelters in Transcaucasia in the second half of the 19th – early 20th centuries. With its help, one of the largest mining enterprises in the region was organized, which belonged to the famous entrepreneurs of the Prussian origin – the Siemens. Forest allotments were required for the procurement of wood fuel for metallurgical furnaces. Using the example of business correspondence between owners and directors of enterprises with regional and central mining authorities, we demonstrate how the conditions of possession, which form the basis of the relationship between owners and the state, influenced the progressive development of the region’s largest mining enterprise. At a certain stage, the rigid connection of the size of forest allotments to the annual productivity of enterprises began to restrict the growth of production, which, in the context of falling market prices, was the only way for the plants to survive. The severity of the fuel problem, on the one hand, caused difficulties in relations with the regional mining administration and an increase in overhead costs, but on the other hand, it pushed the plant management to introduce the latest methods of copper smelting and the use of fossil fuels. Possessional legal relations turned out to be one of the factors that forced the owners to abandon not only forest allotments, but also the further exploitation of a large industrial business, established by many years of hard work.

On dynamic coupling effects of underwater vehicle-dual-manipulator system

In this paper, a novel evaluation framework based on the proposed angular and linear dynamic coupling factors is developed to investigate the complicated dynamic coupling effects of the underwater vehicle-dual-manipulator system (UVDMS). Firstly, the rigid connection coupling effects of the vehicle-manipulator are obtained by adopting the recursive Newton–Euler algorithm, and the hydrodynamic coupling effects are analyzed including the extra added inertial, Coriolis, centripetal and damping effects. Then, the complete dynamic coupling model of UVDMS is derived as a uniform formula. Secondly, the angular and linear dynamic coupling factors are developed to numerically reflect the influence of manipulator movement on the acceleration response of the vehicle. Furthermore, the influence of link mass, length, diameter, mounted position and joint velocity on the dynamic coupling effects are analyzed by simulation study, which provide a guidance for the parameters design of the above manipulator properties. Finally, the relationship between the joint configurations and coupling effects are investigated, and coupling maps with respect to joint variables are obtained. The coupling maps provide the theoretical basis for the trajectory optimization of the manipulators to decrease the effect of dynamic couplings on the system, and the effectiveness of the proposed evaluation framework is verified by the numerical simulation results.

Breaking the stress using pier abutment - A case report

A pier abutment is the lone standing abutment tooth between two critically situated edentulous spaces, in a frequently seen clinical situation, a missing first premolar and first molar is seen, which leads to a design where canine and the second molar acts as a terminal abutments and second premolar acts as a pier abutment. This pier abutment acts as a fulcrum which may lead to debonding of the less retentive terminal abutment during function, to overcome this situation a non rigid connector is advised. This paper presents a clinical case report which describes the incorporation of non rigid connector to rehabilitate the pier abutment case in unilateral maxillary and mandibular region.

Biomechanical evaluation of bridge span with three implant abutment designs and two connectors for tooth-implant supported prosthesis: A finite element analysis

Background/purposeBridge stability under loading was influenced by bridge span with the connector and implant abutment design. Thus, the purpose of this study was to evaluate the effects of rigid and non-rigid connector designs and pontic connections of different abutment systems in the tooth-implant supported prosthesis (TISP) at different span distances on the biomechanical stress distribution of the overall system components. Materials and methodsFor comparative analysis, rigid and non-rigid bridge connections were fitted with three implant abutment systems (one-piece, two-piece and three-piece), and five implant-to-natural tooth distance configurations (12 mm, 14 mm, 16 mm, 18 mm, and 20 mm) were provided. ResultsThe maximum stress between TISP components occurred at the distal side of crown margin of cement1 in rigid connector with one-piece group and the bottom of the crown3 in non-rigid connector with one-piece group, while the other groups were more concentrated at the junction between the mesial side of the implant collar and the abutment. In addition, neither the rigid nor non-rigid connector model showed that stress distribution increased proportionally with the bridge span distance. ConclusionIt was clinically recommended that if the implant with a shorter bridge distance of 12 mm from the natural tooth, the rigid connection of the three-piece abutment can be used as the TISP design. If the bridge distance was 18 mm longer, the non-rigid connection of the three-piece abutment could maintain the physiological movement of the natural tooth and avoid the excessive stress on the bone crest around the implant.

Prestressed CLT-concrete composite panels with adhesive shear connection

The wet-on-wet gluing method seems to be a highly effective way to ensure a rigid shear connection between timber and concrete. However, in this case, the concrete shrinkage induces a relatively high deflection of timber-concrete composite elements. A new type of slender composite floor panel with a high load-bearing capacity was designed: prestressed cross-laminated timber (CLT)-concrete composite panels with an adhesive shear connection, made using the wet-on-wet method. The prestressing of composite panels was induced by releasing both ends of CLT slabs cambered by 3-point bending with a camber of about 1/100 of the panel length. Doing it this way eliminates the negative effect of the wet-on-wet gluing method, as was experimentally proven. Even one year after concreting, the middle-span deflection of the CLT-concrete composite panels was negative, with a residual camber of 5.5 mm. The theoretical model reflecting the phases of the manufacturing process, rheological phenomena and cracking of the concrete proved to be suitable for estimating the behaviour of prestressed CLT-concrete composite panels with adhesive shear connections. The contributions of influencing factors to the deformations and stresses of panels were quantified. The unfavourable effect of shrinkage has been confirmed regardless of the different anchoring times of panels, and the deflection only due to shrinkage exceeded 1/300 of the panel spans. By prestressing the panels, it was possible to achieve about a 1.2 times higher load-bearing capacity compared to the load capacities of non-prestressed panels.

Pier abutment: Bridge the gap with non rigid connector - A clinical case report

Abstract Pier abutment is defined as a freestanding abutment with edentulous space on both sides. This case report described the rehabilitation of a patient who presented to the department with the primary complaint of missing teeth and difficulty in mastication. Intraoral examination revealed missing right maxillary canine and the second premolar, with the lone standing first premolar acting as a pier abutment. To reduce the stress transferred to the abutment and prosthetic assembly, a non-rigid (Tenon-mortise) connector was used in the case, with a keyway (mortise) distal to the pier abutment and a key (Tenon) mesial to the distal pontic.

Structural Performance of Semi-Rigid Connection Steel Frames

In most engineering designs, steel connections are usually considered as fully rigid connections or perfectly pinned connections, for simplicity of design work. In reality, this assumption is incorrect. The behaviour of the beam-column connection is in between of rigid connection and perfectly pinned connection. This type of connection is termed semi-rigid connection. This article represents a numerical analysis using finite element method of structural steel frames to investigate the effect of semi-rigid beam-column connection on the behaviour of the frame. ANSYS software was used for the finite element modelling of the frames. The beam-column connection was modelled as rotational spring with specified rotational stiffness using COMBIN14 element. The study includes investigation the effect of semi-rigid on different study cases such as: support types and number of stories. The obtained results reveal that changing the beam-column connection from rigid case to semi-rigid case with different rotational stiffness can increase the vertical and horizontal displacement of the frame with a percentage depends on the rotational stiffness of the beam-column connection. Changing the support type of the frame from fixed to pinned support or increasing the number of stories with semi-rigid connection can decrease the strength capacity of the frame. This indicates the importance of including the semi-rigid connection in the design and analysis of steel frames to obtain more realistic results.

Conformal Integration of Efficient Conductive-Ink-Printed Antennas in Smart Suitcases for LPWAN-Based Luggage Tracking.

In the context of localization and sensing within the Internet of Things, new antenna manufacturing technologies, such as antennas printed with conductive inks on thin thermoplastic sheets, allow for seamless integration into plastic objects produced by an injection molding process. In this paper, we present printed sensor antennas for the [862–928] MHz band supporting LoRa and Sigfox and the [2.4–2.5] GHz band for WiFi, Bluetooth, and IEEE802.15.4 communication. To integrate them into smart suitcases, the antennas are printed, overmolded, tested, and measured, following a dedicated conformal integration strategy consisting of two design iterations. Additionally, as a more convenient connection to the printed antennas, printed transmission lines along with a dedicated transition to printed circuit board technologies are implemented and characterized, avoiding rigid coaxial connectors that exhibit fragile mounting on flexible substrates. The overmolded stand-alone antennas achieve fractional impedance bandwidths of 26% and 15% covering the [862–928] MHz and [2.4–2.5] GHz bands, respectively, with a substantial margin and with in-band simulated total efficiencies of 94% and 88%, respectively. Finally, the seamless integration of two antennas into a smart suitcase for tracing via Sigfox and WiFi demonstrates the potential of the proposed technique to realize high-performance antennas occupying virtually no real estate.

Numerical study on prequalification and cyclic performance of column-tree connections

Column-tree connections are commonly employed as a shop-welded and field bolted connection in the steel moment resisting frames to ease installation and inspection. The prequalification and cyclic performance of these connections are not completely clear yet. In the present study, using nonlinear finite element analysis by ABAQUS FEA software, the effects of bolted splice location and design method on the prequalification and cyclic behavior of the column-tree connection are investigated. The numerical models are validated based on experimental test results. The numerical analysis results show that the column-tree connection prequalification depends on the stub beam length and bolted splice design method; moreover, the bolted splice configuration influences the monotonic and cyclic behavior, strength, bolts pre-tension loss, stiffness, fracture tendency, ductility, and energy dissipation characteristics of the connection. Also, it is observed that based on the moment strength and rotational stiffness of the bolted splice, the column-tree connection is classified as a rigid or semi-rigid moment connection. This finding needs to be taken into account in the column-tree moment frame design.

Development of composite cold-formed steel-rubberised concrete semi-rigid moment-resisting connections

This paper presents the development of a composite cold-formed steel (CFS)-rubberised concrete (RuC) semi-rigid moment-resisting connection suitable for framed building structures. The connection comprises built-up tubular cold-formed steel beam and column sections connected using side-plate screwed fasteners and infilled with rubberised concrete. A detailed finite element analysis validated against physical tests is employed to model both bare steel and composite beam-to-column connections subjected to lateral and gravity loadings. The governing design limit states are characterized as local buckling in bare steel beams, connection screw shear failure, and side plate plasticity. It is shown that the strength and ductility capacity of composite connections could be increased by up to 1.44 and 3.46 times, respectively, compared with those of the bare steel connections. The connection rigidity of both bare steel and composite connections can be classified as a semi-rigid joint.

(PNSiMe3)4(NMe)6: A Robust Tetravalent Phosphaza‐adamantane Scaffold for Molecular and Macromolecular Construction**

AbstractTetraarylmethanes and adamantanes are important rigid covalent connectors that play a four‐way scaffolding role in molecular and materials chemistry. We report the synthesis of a new tetravalent phosphaza‐adamantane cage, (PNSiMe3)4(NMe)6 (2), that shows high thermal, air, and redox stability due to its geometry. It nevertheless participates in covalent four‐fold functionalization reactions along its periphery. The combination of a robust core and reactive corona makes 2 a convenient inorganic scaffold upon which tetrahedral molecular and macromolecular chemistry can be constructed. This potential is demonstrated by the synthesis of a tetrakis(bis(phosphine)iminium) ion (in compound 3) and the first all P/N poly(phosphazene) network (5).

(PNSiMe3 )4 (NMe)6 : A Robust Tetravalent Phosphaza-adamantane Scaffold for Molecular and Macromolecular Construction.

Tetraarylmethanes and adamantanes are important rigid covalent connectors that play a four-way scaffolding role in molecular and materials chemistry. We report the synthesis of a new tetravalent phosphaza-adamantane cage, (PNSiMe3 )4 (NMe)6 (2), that shows high thermal, air, and redox stability due to its geometry. It nevertheless participates in covalent four-fold functionalization reactions along its periphery. The combination of a robust core and reactive corona makes 2 a convenient inorganic scaffold upon which tetrahedral molecular and macromolecular chemistry can be constructed. This potential is demonstrated by the synthesis of a tetrakis(bis(phosphine)iminium) ion (in compound 3) and the first all P/N poly(phosphazene) network (5).

Transportation of Payload Using Multiple Quadrotors via Rigid Connection

Due to the limited payload capability of an aerial robot, multiple quadrotors can be used to manipulate payloads in aerial transportation, construction, and assembly tasks. This paper focuses on the cooperative transportation of a payload rigidly attached to multiple quadrotor bodies. These quadrotors may have different orientations. The dynamics equation of a rigid body in 3-D space is derived to describe the motion of such a transportation system. Robust position and attitude controllers are designed to drive the system to the desired pose. To assign control signals for each quadrotor, the control command allocation method compatible with the case that partial or all quadrotors are in parallel planes is developed. Finally, experimental results are presented to validate the effectiveness of the proposed controllers and control command allocation methods. Different from classical works in this field, this paper can solve the dynamics modeling, controller design, and control command allocation problems for the transportation of a rigidly connected payload using a team of quadrotors with different orientations.

Biomimetic space debris removal: conceptual design of bio-inspired active debris removal scenarios

The ever-increasing number of man-made space debris creates the need for new technologies to mitigate it. Therefore, within the ESA-funded project BIOINSPACED, biologically inspired solutions for active debris removal were investigated, conceptualized and integrated to innovative and comprehensive scenarios. In the following, the collection process of existing and new biomimetic concepts as well as the evaluation of ten concepts based on a feasibility analysis will be presented. Out of the ten, the three most promising scenarios, were chosen for further investigation and further elaborated in detail specifying the biological models incorporated as well as how the scenario could be implemented in a simple demonstrator. The first scenario (A) is a gecko kit canon and describes a system that fires deorbiting kits towards the target from a safe distance. The second scenario (B) involves a robotic arm with a gecko-adhesive end-effector and a bee-inspired harpoon to achieve a preliminary and subsequent rigid connection to the target. The last scenario (C) is mimicking a Venus Flytrap and its bi-stale mechanism to capture its prey. One of these scenarios will be manufactured and built into a demonstrator to showcase biology’s potential for the development, optimization and improvement of technologies, especially within the space industry.

Functional structure enhanced synergistic sensing from triboelectric–electromagnetic hybrid nanogenerator for self-powered rotating speed monitoring

Abnormal motor speed caused by overload, eccentric load and bearing wear is one of the main fault manifestations of heavy-duty motor. On-line monitoring the speed in real time is of great significance for fault early warning and improving motor operating life. In this paper, a self-powered motor speed sensor based on a coaxial integrated triboelectric–electromagnetic hybrid nanogenerator is proposed. A modular magnet coupling is designed to synchronously transfer energy from the motor shaft to nanogenerator with opposite polarity magnet through non-mechanical contact, which is advantageous to reducing the noise interference induced by rigid connection. The nanogenerator structure is mainly composed of the rotator module including magnet and wear-resistant positive friction material of Polyamide-66 and the stator one fitted with carbon steel enhanced copper coil and negative friction material of PTFE. Especially, an innovative rotating lead structure consisting of a set of rolling and sliding metal balls is fabricated for the first time, which provides a unique solution for transmitting triboelectric charge on rotator. Moreover, the carbon steel column inset into coil hole increases the short-circuit current of electromagnetic generator by 35.2%. The electromagnetic current and triboelectric voltage are used to characterize motor speed in our design, and their sensitivity are 0.035 mA/rpm and 1.365 V/rpm in the range of 0-300 rpm, respectively. When they were conjointly analyzed, the linearity of sensor reaches 0.995, which is attractive and greatly enhances the accuracy using sensing signal to judge the abnormal state. Furthermore, maximum output power of the nanogenerator reaches 76.91 mW, which shows that the nanogenerator is Competent for self-powering the sensor and its controlling circuits. The experimentally results indicate that the proposed self-powered sensor provides a novel design concept for the measurement of rotation speed and exhibits immense potential in industrial detection and mechanical failure early warning.