Plug-in Connector Research Articles

Seismic evaluation of a self-centering retrofit solution for modular steel structure connections

In this study, a novel plug-in modular steel structure (MSS) connection is proposed, in which the connector, cover plates, and bolts form a complete connecting system. To improve the seismic performance and post-earthquake functional recoverability of the MSS connection, a retrofit solution with diagonal self-centering (SC) haunch braces is introduced, and the self-centering modular steel structure (SC-MSS) connection is developed. Theoretical analysis of the mechanical properties of the MSS and SC-MSS connections are conducted, and the calculation formulas for the initial stiffness and bending bearing capacity are derived. A comparative experimental study of one MSS connection and five SC-MSS connections under cyclic loading was carried out to evaluate their seismic performance, and to explore the influences of the main haunch parameters on the behavior of the SC-MSS connection. The results demonstrate that the plug-in connector, cover plate, and bolts can realize reliable continuity and integrity between modules. The SC haunch braces have good collaborative work with the modules and provide sufficient restoring force, and the damage in all the SC-MSS connections was found to be effectively controlled and delayed as compared with the MSS connection. The MSS connection displays a full shuttle-shaped hysteretic response with adequate plastic development, while the SC-MSS connections successfully exhibit expected flag-shaped hysteretic responses with higher bearing capacity and lower residual displacement. The adjustment of the post-activation stiffness and pre-pressed force of the haunch brace is found to improve the connection performance, and a reasonable selection of the installation scheme could achieve optimal self-centering efficiency. The experimental results also verify the feasibility and correctness of the proposed theoretical formulas and mechanical assumptions.

A Study on Mechanical Performance of an Innovative Modular Steel Building Connection with Cross-Shaped Plug-In Connector

Modular steel buildings show high assembly degree and fast installation speed. The inter-module connection (IMC) is one of the key technologies that restrict the robustness of modular steel buildings. An innovative IMC with a cross-shaped plug-in connector is proposed, and the connection consists of end plates of columns, the cross-shaped plug-in connector, bolts, cover plates, and one-side bolts. The proposed IMC is easily constructed, and the cross-shaped plug-in connector can improve the shear resistance of the core area. The mechanical model of the proposed IMC is presented, and the panel zone volume modified factor and initial rotational stiffness modified factor are proposed for calculating the shear capacity of the panel zone and the initial rotational stiffness. Numerical simulation was conducted considering the influences of axial compression ratios, sections of beams and columns, and the thickness of the tenon plate of the connector. The bearing capacity of the proposed IMC was analyzed, and the values of the two factors mentioned above were calculated, and their regression formulas are presented. The results show that the sections of beams and columns and the axial compression ratios show great influences on the bearing capacity of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector shows almost no effect. In addition, the sections of beams and columns show great influences on the shear capacity of the panel zone, as well as the initial rotational stiffness of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector and the axial compression ratios show little effect and almost no effect, respectively. Furthermore, the bending moment limit of the beam end of the proposed IMC is suggested to be 0.6 times the resistance bending moment, and the proposed IMC is considered to be a rigid connection or inclined to a rigid connection The proposed IMC has good mechanical performance, and design recommendations are presented.

Experimental evaluation on seismic performance of a novel plug-in modular steel structure connection system

A novel plug-in modular steel structure (MSS) connection with cover plates for assembly efficiency, flexible serviceability, and stable workability is presented in this study. A seismic retrofit solution with self-centering (SC) haunch braces is then utilized for the MSS connection, aiming at damage mitigation and post-earthquake functional recoverability. In order to confirm the structural characteristics and evaluate the seismic behaviors of the MSS and self-centering MSS (SC-MSS) connections. Three corner connections were designed, manufactured, and tested under cyclic reversed loadings, including two MSS connection specimens with different design parameters and one SC-MSS connection specimen. Test results indicate that the two MSS connection specimens havetheabilityto make full development of the plastic strength of the modular beams and fail in the weld tearing, steel fracture, and local buckling of the beam flanges. The higher tenons of the plug-in connector enhance the local strength of the columns, guaranteeing more concentrated plasticity in the beams for better ductility. In comparison to the MSS connection specimens, the SC-MSS connection specimen has greatly improved stiffness, strength and displays the expected flag-shaped hysteretic responses with a satisfactory self-centering capability. The SC haunch braces effectively control the damage development in the connection core region and the surrounding components, mitigate the deterioration of global strength, significantly reduce the residual deformation, and thus achieve functional recoverability of the connection system. Furthermore, due to the prominent contribution of the haunch braces to the stiffness and strength, the SC-MSS connection shows great potential for sustainable and stable energy dissipation. This experimental study offers a reference for the practical design and application promotion of modular steel structures.

Contact Failure Diagnosis for GIS Plug-In Connector by Magnetic Field Measurements and Deep Neural Network Classifiers

This article presents a contact fault diagnosis method of gas-insulated switchgear (GIS) plug-in connector via magnetic field measurement, magnetic field visualization, and deep neural network (DNN) classifiers. First, the surrounding magnetic field of GIS plug-in connector with normal contact (NC) condition and with artificially designed contact failures was measured by the Hall sensor array. Then, the measured magnetic field was gathered with an original matrix of 16 <inline-formula> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 16 dimensions. The <inline-formula> <tex-math notation="LaTeX">$\vert$</tex-math> </inline-formula>original matrix was then visualized by the max&#x2013;min normalization and correlation matrix. Database containing 11 000 magnetic field images was labeled and segmented as training, validation, and test datasets. Furthermore, high-dimensional features of input magnetic field images were extracted by different DNN filters, including convolutional neural network (CNN), simple recurrent neural network (Sim-RNN), and long short-term memory (LSTM) network. Then, extracted high-dimensional features were fed into a fully connected (Fc) neural network with SoftMax classifiers to identify different contact faults. Finally, the performance of different DNN-based classifiers is compared by the fault classification merits, <inline-formula> <tex-math notation="LaTeX">$t$</tex-math> </inline-formula>-distributed stochastic neighbor embedding (<inline-formula> <tex-math notation="LaTeX">$t$</tex-math> </inline-formula>-SNE) feature clustering, and confusion matrixes. Results show that the DNN-based model could achieve contact fault classification task with an accuracy of 97.7% and <inline-formula> <tex-math notation="LaTeX">$F_{1\_\mathrm{score}}$</tex-math> </inline-formula> of 0.985. Therefore, the proposed method is useful for designing a high-performance contact status monitoring system of GIS equipment, thus improving its operation safety.

Theoretical and parametric studies of a self-centering modular steel structure connection

A novel modular steel structure (MSS) connection using symmetrical self-centering (SC) haunch braces is proposed to expand the current research limits and create a modular structure with superior seismic resilient performance and functional recoverability after earthquakes. An advanced connection technique of the modules consisting of a cross-shaped plug-in connector, cover plates, and several bolts is used to provide adequate stiffness and ensure structural integrity. A theoretical model of the self-centering MSS (SC-MSS) connection system is established to evaluate the haunch brace effects on the key components, and the model is validated by simulations. The effects of the dimension of the plug-in connector, the location and performance parameters of the SC haunch brace, and the haunch brace configuration on the seismic resilient performance of the connection are analyzed. The SC-MSS connections exhibit satisfactory self-centering capability, and the bearing capacity is substantially higher than that of the MSS connection. A large tenon height in the connector increases the local strength of the column flanges, ensuring the ductile failure mode in areas of concentrated plasticity in the beams. As the installation distance, angle and pre-stressed force of the SC haunch brace increases, the bearing capacity and self-centering capability of the connection are effectively improved. The stable and expected behavior of the connection with the non-symmetrical haunch configuration demonstrates the feasibility of the independent selection of the haunch patterns of each module. The additional strength and stiffness provided by the SC haunch braces result in acceptable energy dissipation of the SC-MSS connection and significant damage reduction.

Development and seismic retrofit of an innovative modular steel structure connection using symmetrical self-centering haunch braces

As an efficient and environment-friendly technique that combines off-site manufacturing of modules and on-site assembly, modular buildings have been adopted in many areas of the construction industry. This paper proposes an innovative modular steel structure (MSS) connection with bolted cover plates, which inserts a cross-shaped plug-in connector inside the adjacent columns to achieve accurate positioning in the module installation and provide partial shear capacity. A seismic retrofit method using hinged diagonal self-centering (SC) haunch braces is proposed for the MSS connection to improve the seismic performance and achieve functional recoverability after earthquakes. Hysteretic behaviors of the MSS connection and the self-centering MSS (SC-MSS) connection are investigated due to cyclic loadings. Results demonstrate that compared with the MSS connection, the SC-MSS connection is expected to improves strength and stiffness and exhibits stable flag-shaped hysteretic responses with a satisfactory self-centering capability. The hinged diagonal SC haunch braces are capable of reducing the average stress level around the connection core region, controlling the development of plastic damage, avoiding the local failure, and improving the ductility of connection. The present study provides practical connections and important guidance for the applications of modular steel structures in the medium- and high-intensity seismic regions.

Study on the Wear and Abrasion Effect of Metal Nano-Coating Plug Connectors Under Atmospheric Corrosion Conditions

The plug connector is the most widely used type of separable connector; however, the sliding friction that occurs during the plug-in process causes wear and wiping effects. Wear is a form of damage that occurs to the anti-corrosion coating during the sliding process, and wiping refers to the cleaning effect of corrosion products during the sliding process. Both have negative and positive effects on electrical contact reliability in corrosive environments. Therefore, wear and wiping are key factors in studying the life and reliability of connectors in atmospheric corrosion environments. Atmospheric corrosion is the main mechanism leading to connector contact failure. There have been many related studies on simple connector atmospheric corrosion, but research on the influence of wear and wipe on atmospheric corrosion and the influence of contact resistance degradation is still not comprehensive. To study the influence of wear and wiping on contact reliability during the plug connector-mating process, this work evaluates the metal nano-coating connector plugging process as the object, and the contact resistance degradation model under atmospheric corrosion as the basis, and the effect of wear and wiping on corrosion degradation as the research tool. Ultimately, the influence of wear and wiping on contact resistance is studied in detail. Finally, combined with the actual usage of the plug-in connector, the contact reliability of metal nano-coating plug connectors under the action of abrasion and wiping is studied.

Deterioration Behavior Analysis and LSTM-Based Failure Prediction of GIB Electrical Contact Inside Various Insulation Gases

Plug-in connector of gas insulated bus (GIB) could be subject to the wear and electrical contact resistance (ECR) deterioration processes under cyclic mechanical and current loads. A specific test platform is designed to simulate the current-carrying wear and ECR degradation process of Ag-plated GIB electrical contact spot inside SF6, N2 and Air insulation mediums under current loads. Worn surface morphology and chemical composition are observed and analyzed. Influence of insulation medium and current load on deterioration mechanism of GIB electrical contact are discussed. Raw ECR curve obtained from current-carrying experiment is smoothed by the exponentially weighted moving average (EWMA) method. A long short-term memory (LSTM) neural network is then proposed to realize both single-step and multi-step ECR and failure predictions of GIB electrical contact. Results show that adhesive wear on contact surface happened due to materials transfer. Deterioration of contact spot inside air medium is much severer than those in SF6 and N2 due to oxidation effect. Deterioration of contact spot inside SF6 medium under high current load is severer than those under low current load due to the change of wear behavior and chemical reactions. Compared with other methods, LSTM could achieve better performance in both single-step and multi-step failure prediction of GIB electrical contact.

Studies on Contact Degradation Process and Failure Mechanism of GIB Plug-In Connector

Overheating faults of gas-insulated bus (GIB) plug-in connectors induced by contact degradation seriously threaten the safe operation of equipment and power system. Multiphysics coupled numerical simulations and physical experiments were conducted in this article to reveal contact degradation processes of the GIB plug-in connector. First, electromagnetic-thermal-mechanical coupled finite-element (FE) model was built. Relative motion between contact interfaces was considered by low-velocity Stribeck friction model. FE model was verified by physical experiment. Second, influences of operation current, spring stiffness, and conductor insert depth on contact temperature rise were analyzed. Results show that insufficient conductor could induce overheating on several contact spots then accelerate the degradation process. Third, thermal and motion characteristics under cyclic operation currents and short-circuit (SC) current impact were analyzed. Results show that conductor insert depth could be changed by relative motion between contact elements. Relative motion accumulates gradually under cyclic thermal loading by operation current. Significant relative motion and temperature rise could be induced by SC current impact. Finally, progressive and sudden failure mechanisms of the GIB plug-in connector were discussed. Research result may guide optimal design and field maintenance of GIB equipment, and thus improves its reliability.

Multi-Physics Calculation and Contact Degradation Mechanism Evolution of GIB Connector Under Daily Cyclic Loading

A 3-D electromagnetic-thermal-mechanical coupling finite element model of a gas-insulated bus plug-in connector is proposed in this paper with a subsequent analysis for the contact fatigue mechanism. Special attention has been paid to the contact degradation mechanism under normal cyclic operation conditions, which is important for the optimal designing and condition monitoring of the equipment. The current constriction effect and the contact resistance are considered through modeling the equivalent contact bridges between contact interfaces, and the current densities derived from the electromagnetic field are applied as load inputs in a electrical-thermal-mechanical analysis where varying of friction coefficient is considered. The validity of the calculation model has been demonstrated by temperature rise and relative motion experiments, and the influence of daily changing current and environmental temperature on the thermal and mechanical characteristics of plug-in connector has been analyzed. Analysis results show that the temperature rise among different contact fingers of plug-in connector is not the same with different contact forces, and the plastic deformation can be induced on contact spots. The insert depth of connector can be changed under the action of alternating thermal loading induced by daily change of current and environmental temperature, leading to contact degradation and overheating fault of plug-in connector.

Multiphysics Analysis of Plug-In Connector Under Steady and Short Circuit Conditions

With the aim of providing an effective method for optimal design and condition monitoring of the plug-in connector used in gas-insulated switchgears, a 3-D coupled field finite-element method model has been developed for analyzing the electrical, thermal, and mechanical behaviors of a plug-in connector under steady and short circuit conditions. Contact resistance and electromagnetic repulsion force are considered by modeling an equivalent contact bridge between contact interfaces. Electromagnetic force and temperature derived from electromagnetic-thermal coupled field calculation are used as the load inputs in thermal-mechanical coupled field analysis. The validity of the calculation model is demonstrated by temperature rise experiments and comparing with other closed formulas. Dynamic behaviors of a plug-in connector under short circuit conditions have been also analyzed.

New Thermal Management Systems for Data Centers

Energy consumption in data centers has seen a drastic increase in recent years. In data centers, server racks are cooled down in an indirect way by air-conditioning systems installed to cool the entire server room. This air cooling method is inefficient as information technology (IT) equipment is insufficiently cooled down, whereas the room is overcooled. The development of countermeasures for heat generated by IT equipment is one of the urgent tasks to be accomplished. We, therefore, proposed new liquid cooling systems in which IT equipment is cooled down directly and exhaust heat is not radiated into the server room. Three cooling methods have been developed simultaneously. Two of them involve direct cooling; a cooling jacket is directly attached to the heat source (or CPU in this case) and a single-phase heat exchanger or a two-phase heat exchanger is used as the cooling jacket. The other method involves indirect cooling; heat generated by CPU is transported to the outside of the chassis through flat heat pipes and the condensation sections of the heat pipes are cooled down by coolant with liquid manifold. Verification tests have been conducted by using commercial server racks to which these cooling methods are applied while investigating five R&amp;D components that constitute our liquid cooling systems: the single-phase heat exchanger, the two-phase heat exchanger, high performance flat heat pipes, nanofluid technology, and the plug-in connector. As a result, a 44–53% reduction in energy consumption of cooling facilities with the single-phase cooling system and a 42–50% reduction with the flat heat pipe cooling system were realized compared with conventional air cooling system.

A reply

Thank you for the opportunity to respond to the letter from Drs Liew and Jayamaha. The customers worked in the correct manner and carried out checks and recommendations given in the instructions for use of D-Vapor vaporisers (their reference [1]) and of Professional Standard PS 31 of the Australian and New Zealand College of Anaesthetists, ‘Recommendations on Checking Anaesthesia Delivery Systems’, clauses 4.2.3.2.3 and 4.2.3.2.4 (their reference [2]). They observed a fresh gas leak caused by inappropriate handling of a D-Vapor and found the reason for that to be a broken part of the bolt of Selectatec-compatible plug-in adapter S-2000. The damaged vaporiser had been replaced and the broken part was removed from back bar. With an alternative D-Vapor, all tests and checks in combination with the cited anaesthesia machine were passed. During the investigation, the customer found that excessive force during previous handling was the most likely cause of breaking the locking bolt of the plug-in adapter. Excessive force during handling would constitute improper handling of the device. Our instructions for use state that ‘D-Vapor has to be handled with care’. The vaporiser discussed must be repaired by trained personnel who have had product-specific Draeger training. Training of the operating room staff using the anaesthesia system shall be conducted again. We are grateful for being made aware of the issue and the advice of the author to check and/or to improve the locking mechanism with respect to the bolt material used. The locking mechanism has been present on anaesthesia machines from both GE/Datex Ohmeda and Draeger for decades. The parts of the locking mechanism are specified as metal parts and were verified/validated by wear and tear tests as well as lifetime endurance tests in conjunction with the plug-in connector, better known as ‘back bar’ or ‘mounting bar’. Our worldwide Quality Surveillance System does not reveal any accumulated reports of the adapter or the bolt in particular. For these reasons, we would not anticipate a need to change the design of the adaptor or the bolt in particular. In conclusion, we recommend appropriate handling of medical devices and want to reassure all customers of Draeger-Vapor vaporisers equipped with a Selectatec-compatible plug-in adapter S-2000, that the design is field-established, certified by TÜV SÜD (a testing and certification body) and received a CE certificate of compatibility in 2006.

EXTERNAL OUTPUT CONNECTOR AND CABLE FOR WIRE ELECTRODE RECORDING IN FREELY MOVING MOUSE

It is a tricky task to record electrical signals from the subcutaneous fixed tether assembly in freely moving mouse. The thin and pliable skin of the mouse is easily rent at the sutured incision site by dragging of the external output set during movement. We constructed a light weight chassis that made the output plug-in connector tightly fixed at the muscle. It could resist a lot of pulling force produced by the movement of the mouse. Furthermore, the plug-in connector protruded out off the skin only by a silicone tube. The thin cylinder configuration of the silicone tube made it possible for the incision to be sutured finely and the flexible and smooth characteristics of the silicone tube could buffer the pulling force to avoid subjecting the skin to mechanical tear. A shielded external output cable feature which was light weight and flexible was also made, resulting in less loading on the mouse and without impediment during movement.

Effect of Edge and Internal Point Support of a Printed Circuit Board Under Vibration

This paper presents an investigation into the vibration of a PCB that is supported on its three edges by two wedge retainers and a plug-in connector. Using a vibration test fixture to couple the PCB structure to an electromagnetic shaker, experiments were conducted to determine its dynamic response. The wedge retainer and connector are modeled as simply supported condition with appropriate rotational spring stiffnesses along their respective edges. It is found that these supports behave somewhere between the simply supported and clamped boundary conditions and provide a percent fixity of 39.5 percent more than the classical simply supported case. It is further found that a single internal point constraint that would yield the maximum fundamental frequency is located at the intersection of the nodal lines of mode 2 and mode 3. This has the effect of significantly increasing the PCB’s fundamental frequency from 68.4 Hz to 146.9 Hz, or 115 percent higher.

Dynamic Finite Element Model Improvement of a PCB Structure

The purpose of this research is to apply an eigensensitivity-based method to develop an accurate representation of the in-service boundary conditions of structures. By implementing the method on a printed circuit board (PCB) supported on its three edges by two opposite wedge retainers and a plug-in connector, it is shown to be effective in producing an accurate finite element model of the PCB structure. The result shows that the percentage error in the fundamental frequency of the PCB finite element model is substantially reduced from 22.3% to 1.3%. Furthermore, convergence to an accurate finite element model is found to be rapid.