Connector Model Research Articles

Constitutive modelling of deformation rate dependent response of steel timber shear connections

This paper presents experimental and numerical investigations into the deformation rate-dependent constitutive response of steel-timber shear connections with screws. After describing the test specimens and experimental arrangement, a detailed account of the complete deformation response and main mechanical parameters of the tested shear connections under three applied displacement rate levels are given. Specimens with small screw diameters had a relatively brittle response, failing shortly after yielding, whilst those with higher diameters showed ductile failure modes, with plastic hinges forming in the screws and concurrent extensive timber crushing. It was observed that the stiffness increases with the deformation rate due to the viscoelastic response of wood materials, whilst the peak load is largely constant. Nonlinear finite element simulations were carried out to validate the main numerical parameters for steel, timber, and interaction characteristics. After gaining confidence in the ability of the numerical models to predict closely the stiffness and peak load, numerical investigations were carried out to examine the influence of key material and geometric parameters on the stiffness, load resistance and deformation response. The studies showed that higher timber strength increases the initial stiffness and the peak load, while higher screw grades improved both stiffness and strength. Based on the results and observations, code-modified expressions for evaluating the stiffness and load resistance, as a function of the deformation rate, are proposed within the ranges considered, and validated against a collated database. Comparative assessments with existing literature indicate that the proposed equations provide improved estimates. Suggested closed-form relationships enable the characterisation of the full constitutive response of steel-timber shear connections, that can be adopted for discrete nonlinear modelling of connectors.

Performance of channel shear connectors in steel frame with reinforced concrete infill walls

To examine the mechanical properties of channel shear connectors employed in steel frame with reinforced concrete infill wall (SRCW) structures, the improved push-out tests were performed on three specimens of channel shear connectors subjected to the monotonic and cyclic loading. This study investigated the influences of loading protocol and concrete strength on the mechanical behavior of channel shear connectors. After the refined finite element (EF) models of channel shear connectors were validated based on the push-out tests, a systematical parametric analysis was conducted to evaluate the effects of RC infill wall thickness, concrete strength, and channel dimensions on its shear strength of the channel shear connectors. In addition, this study also compared the accuracy of the CSA S16, AISC 360 and GB50017 design code in predicting the shear capacity of channel shear connectors in SRCW structures. The experimental results and parametric studies indicated that the current design equations inaccurately evaluate the shear capacity of channel shear connectors used in SRCW structures. Consequently, an alternative equation was developed to estimate the shear-resistant capacity of channel shear connectors in SRCW structures, which provided the desirable calculation precision for engineering design.

Shear Connectors Behavior Under Elevated Temperature: A review

A composite member is described as a structural steel shape that has been built up or rolled and filled with concrete, covered in reinforced concrete, or structurally attached to a slab of reinforced concrete. The shear connection between the steel beam and the concrete slab is the primary component of the composite beam. In risky situations, like building fires, the performance of a composite structures and steel structures are heavily dependent on the execution of connection. Numerous kinds of shear connectors exist and being utilized in the construction engineering rendering to their use. This paper reviews research conducted in the past years on the performance of shear connectors such as (ASTM A325 bolts, channel shear connector, T, T-mass and T-Proband shear connectors) exposed to raise heat degree. This research covers the experimental testing of push-out specimens, behavior of connectors in steel structures, various shapes of shear connectors under elevated temperatures, main failure modes, finite element modeling of shear connectors, design approaches offered by investigators, and various codes. Compared to the size of work available on shear connectors at room temperature, relatively slight research has been done on the conduct of shear connectors (studs) under high temperature. In addition, this report indicates several topics that need further investigations. Through this article, it was concluded that when temperatures raise, the strength of all shear connectors decreases proportionally regardless of its shape and type. A comparative study showed that the channel connectors are an economic and reliable option to standard shear connectors. Among the findings of some studies is that the effect of temperature on the shear resistance of head stud connector is significantly above 400℃, whether the test is done at temperature or post temperature conditions. Also, adding some materials to the concrete mix such as carbon nanotubes will be not effective on the ultimate shear at temperatures less than 400 ℃, but it reduces the spalling and cracking of the concrete. In general, the influence of elevated temperatures on the ultimate shear capacity of the headed stud connector is noticeably clearer when the test was conducted at exposed to certain temperature compared to post temperature conditions (the test is conducted after exposure the specimen to heat and cooling).

Numerical and experimental investigations of cracked light-frame timber walls

This study investigates the impact of sheathing panel cracks on the structural performance of light-frame, modular-based timber buildings, focusing on the racking stiffness and strength of the individual timber walls in the modules. Previous research has investigated such walls for decades and lead to practical design methods in the harmonized European design code, Eurocode 5. Such hand calculation methods are effective for simple geometries but for walls with openings or complex forms, a correct prediction of stiffness and strength is considerably harder to achieve and load levels where cracks initiate are almost impossible to predict. The paper presents both experimental and numerical studies to investigate how significant cracking in sheathing panels affects the load-carrying capacity of various light-frame timber walls. Finite element simulations using Abaqus are conducted to model the cracking of sheathing panels with the extended finite element method. Moreover, an orthotropic elasto-plastic connector model is introduced for the nail joints. The results indicate that significant cracking of the sheathing panels influences the stiffness and the load-carrying capacity of the wall elements and that the crack initiation and propagation is strongly affected by factors such as the location of openings, the shape of the sheathing panels and the type and position of sheathing-to-framing connections. The numerical results presented align satisfactory with the experimental data particularly regarding load levels at crack initiation and propagation. Furthermore, a parametric study investigates how cracks, orthotropic connector properties and vertical constraint of bottom rails influence the racking strength of different timber walls.

Comprehensive analysis of electro-mechanical characteristics and new regression models of a novel slanted groove electrical connector

Electrical connectors are crucial electro-mechanical components, with insertion, withdrawal, and electrical contact characteristics serving as key indicators of their reliability. Studying the electro-mechanical characteristics and regression models of electrical connectors is vital to enhance their reliability. This work focuses on the M2-type electrical connector, investigating its electro-mechanical characteristics and developing a regression model. A withdrawal force calculation model is established using cantilever beam theory. Simulation and analysis provide data on insertion force, contact pressure, and contact resistance. Experiments on insertion, withdrawal, and electrical contact are conducted using an insertion force tester and a DC low-resistance instrument, comparing experimental results with simulations. The study reveals the fitting relationship between contact pressure and contact resistance for the M2-type connector. Key findings include a stable fluctuation in contact pressure with a relative error of 1.72% between simulated and tested values, an average discrepancy of 3.81% for insertion force, and 2.38% for withdrawal force, with insertion force slightly higher than withdrawal force. Contact resistance shows a U-shaped trend with pin displacement, with an average experimental error 3.70% and 1.16% lower than theoretical values (4.86%). The new regression model (quadratic polynomial fitting) demonstrates mean absolute percentage errors of 0.1458% for simulation values and 0.2219% for experimental values, significantly lower than those obtained using theoretical formulas (0.7046% and 0.3451%). These results provide theoretical guidance for studying electro-mechanical characteristics and designing experiments for electrical connectors, offering valuable insights for designing and ensuring the reliability of new types of electrical connectors.

Shear strength damage model and damage removal FE modeling of stud shear connectors embedded in UHPC

The study conducted a series of push-out tests to study the shear strength of studs as shear connectors in steel-UHPC (ultra high-performance concrete) composite structures. The damage removal modeling was developed and utilized to simulate stud damage caused by welding defects, concrete cracking, and lifting effects. The study investigated the impact of stud damage on the static performance and shear strength of studs. Results indicated that when the root area of the stud was damaged, the shear strength and stiffness of the stud decreased with the damage degree. When the stud root was damaged within 5%h (h is the height of stud shank), it had a significant effect on the shear strength of the stud. Damage outside the 5%h range of the stud root had no significant effect on the shear strength of the stud. And a shear strength damage model was firstly proposed to reveal the damage mechanism of studs. A reduction factor K was proposed to account for the loss in shear strength caused by stud damage. Two methods for calculating K, namely the area reduction method and the equivalent area method, were developed. The calculated values of shear strength considering stud damage were obtained and verified by comparing the calculated values with the test results. The proposed method offers a better prediction of shear strength for damaged studs in UHPC.

Behavior and Large-Scale Modeling of Multi-Sheet Aluminum Connections With Self-Piercing Rivets

Abstract This paper presents an experimental and numerical study on the mechanical quasi-static behavior of self-piercing rivet (SPR) connections with three stacked sheets made from an AA6016-T4 aluminum alloy. The goal was to study the effects of sheet thickness and stack up of the SPR connection under large deformation and failure. Several different types of tests were performed to investigate the initial load-bearing capacity as well as the remaining capacity after partial joint failure. Additionally, the performance of state-of-the-art constraint modeling techniques was evaluated. The parameters for large-scale connector models were found through inverse modeling of the experiments. The models were validated against an additional test configuration where the middle sheet was load-free.

Reliability evaluation of CAN-bus connectors with tailored testing

ABSTRACT Controller Area Network (CAN-bus) is a default solution for digital control in machinery. The CAN-bus structure uses connector components to extend cabling and join subsystems. The connectors are IP-classified, so they tolerate humidity and particle ingress. Ingress protection also provides durability against other stress factors. Usually, connectors are exposed to multiple stress factors, but the stress levels are durable. In mining applications, however, stress levels can be high, and other factors become significant, so IP classification does not necessarily indicate sufficient durability. Tailored testing can be used to identify suitable components for a specific purpose. In this study, the actual stress factors of an underground mine drill were used in tailored tests. The results showed significant differences in reliability between connector models with the same IP code. The ranking of the components varied depending on the stress factors used. This highlights the importance of using actual operating conditions when evaluating reliability.

Effect of necking and polydispersity in aggregate and primary particle size on the scattering matrix of soot aggregates

Morphology of soot aggregates includes complex structures such as necking and polydispersity in aggregate and primary particle size, which have considerable influences on their optical behavior. In this study, a comprehensive analysis of the impact of necking and polydispersity in aggregate and primary particle size is conducted to identify their effects on scattering matrix elements. Typical morphological parameters associated with flame-soot are used to generate aggregate representations via a tunable algorithm based on cluster-cluster aggregation. Necking is implemented via a modified cylindrical connector model and the level-set function model with different coefficients, whereas polydispersity in aggregate and monomer size is introduced assuming log-normal distributions. Scattering properties are calculated via discrete dipole approximation and multi-sphere T-matrix method. Individual impacts of these morphological features on the scattering matrix elements are presented, and the aggregate volume based approach is evaluated for representing the impact of necking. According to the results, the impacts of necking and primary particle polydispersity are similar and dominated by the resultant volume change, whereas that of aggregate polydispersity is more complicated. Accordingly, the aggregate volume based approach performs well in representing the effect of necking on the scattering matrix for the specified cases. The deficiency of the aggregate volume based approach is discussed and a potential way to improve it is proposed.

Numerical modelling of cold-formed steel built-up columns

Built-up cold-formed steel structural members can provide technically and economically advantageous solutions in cold-formed steel construction. However, there is a need for a deeper understanding of their stability behaviour, and this paper demonstrates that detailed, accurate and reliable finite element models provide an excellent means to achieve this. Apart from the typical issues to be considered in the high-fidelity modelling of thin-walled members, which include geometric and material nonlinearity, element type, mesh density, and the modelling of imperfections and boundary conditions, the paper focuses on two additional complications which arise in built-up members: the modelling of connectors, and contact between constituent parts. A number of alternative techniques to model connector behaviour are investigated and their effect on the predictions of the ultimate capacity quantified by benchmarking against experimental data. Various successful strategies to mitigate stubborn convergence problems, which almost inevitable originate when modelling complex contact problems, are also presented. It is demonstrated, however, that the inclusion of contact as a model feature does not have a significant effect on the predicted capacity in the majority of the considered cases, with its influence typically remaining limited below 10%. The validated models were further used in parametric studies which showed that once the connector spacing is short enough to prevent global instabilities of the component sections between connector points, its effect on the ultimate capacity of the built-up column is very small within the practical range of connector spacings. Modelling connector lines as continuous longitudinal constraints tying surfaces together, on the other hand, is bound to significantly overestimate the capacity.

Contact reliability modeling and assessment of electrical connectors with multi-aperture slotted leaf spring contacts

Multi-aperture electrical connectors are widely used in the aerospace system to provide high-reliability and high-quality connections. The existing reliability assessment methods only focus on the single-aperture electrical connectors, and ignored the influence of the aperture difference on the reliability of electrical connectors, which may lead to errors in the evaluation results. In order to assess the contact reliability of multi-aperture electrical connectors at storage environment, this paper build a mathematical relationship between structure parameter of contact pairs and contact force by analyzing the slotted leaf spring jack reed structure of the contact pair and using the cantilever beam model. Based on the growth law of the oxide layer on the surface of the contact pair, the degradation trajectory model of the contact pair performance was set up which incorporating the structure parameters of contact pairs, such as pin diameter, reed length, radius of curvature of the inner and outer surfaces, and the acceleration model was established by combining the Arrhenius equation. Then based on the established degradation trajectory model, the degradation failure distribution model of contact pairs was derived, and the contact reliability evaluation model of multi-aperture electrical connectors was established by using the weakest ring model. The test scheme of constant stress accelerated degradation of electrical connectors was formulated and carried out. Finally, this paper verified the correctness of the model through analyzing the test data, and obtained the reliable life of multi-aperture electrical connectors under the storage environment temperature, which realized the contact reliability assessment of multi-aperture electrical connectors.

Reliability Analysis of the Deep-Sea Horizontal Clamp Connector Based on Multi-Source Information from an Engineering Background

As a key piece of equipment in underwater production system, a reliability study of deep-sea connectors has important theoretical significance and engineering value for increasing fault-free operation time, improving engineering safety, and reducing maintenance costs. However, the diverse failure modes of connectors and the lack of high-quality and credible reliability data can lead to biased analysis outcomes. To tackle this problem, this study aims to establish a reliability model for deep-sea horizontal clamp connectors. Based on the actual engineering background, a fault tree model for deep-sea horizontal clamp connectors is developed, and the distribution types of bottom events are analyzed concerning the failure mechanism. To enhance the model’s credibility, a multi-source information approach is employed, combining prior product information, expert experience, and design information to quantitatively solve the reliability probability of the connector. The expert experience is quantified using the fuzzy quantitative analysis method, while the design information is estimated by developing a corrosion prediction model combined with grey theory. Thus, the reliability assessment of deep-sea horizontal clamp connectors is completed. Factory Acceptance Test (FAT) is performed on the improved connectors, and the closed-loop work of reliability analysis is completed.

Different necking models in predicting the measured scattering matrix of soot aggregates

Generating realistic aggregates is crucial for accurate optical characterization of soot. Necking is a minor structural defect that is commonly observed in soot aggregates, but it is generally not implemented in numerical soot aggregates attributable to the challenges in modeling necking properly and conducting simulations on the resultant complex structures. In this study, a methodology is developed to conduct a quantitative analysis of the performance of different necking models in estimating the scattering matrix elements of soot based on comparisons with measurement data. Morphological parameters and measured scattering matrix associated with re-aerosolized toluene soot samples are derived from an experimental study in the literature. Aggregates formed by both monodisperse and polydisperse primary particles are generated via the tunable algorithm with particle-cluster aggregation based on the derived morphological parameters. The level-set function model and a modified cylindrical connector model are used to implement necking to neighboring primary particles of different levels. The scattering simulations are conducted based on the discrete dipole approximation. The resultant scattering matrix elements are compared with the experimental data and the performances of different necking models in predicting the measurement data are discussed. According to the results, implementing necking is not sufficient to predict the overall scattering matrix elements accurately, but it has considerable effects on specific scattering matrix elements which contributes to diminishing deviations from the measurements. Additionally, the differences in accuracy of the two alternative necking models are insignificant for comparable aggregate volumes. The modified cylindrical connector model is favored considering its simplicity.

Neural network modelling of mechanical joints for the application in large-scale crash analyses

This paper presents an artificial neural network (NN) modelling approach to represent a connector model in large-scale finite element explicit crash simulations. The NN model was established to describe the local force–deformation response of point connectors in automotive applications, namely self-piercing rivets and flow-drill-screws. The study is limited to two-sheet connections and to the use of feedforward NNs. Successive loading and unloading of the joints is not studied. Various architectures and complexities of the feedforward NNs were evaluated and trained based on data generated from a constraint model found in the literature. This forms a proof of concept for implementing a modelling technique not based on physics-motivated constitutive equations. The impact of the network complexity and training data diversity was investigated. The NN model was implemented as a cohesive zone model for incremental force prediction in an explicit finite element code. In order to have a wide selection of joint types, five different joint configurations including self-piercing rivets (SPR) and flow-drill screws (FDS) were investigated. Numerical results from the NN model were compared to physical tests from all joint configurations. It was shown that a rather basic machine learning technique like a feedforward NN was able to reproduce path-dependent force–deformation behaviour for the application in explicit FE solvers.

基于退化量分布的电连接器绝缘可靠性建模

基于退化量分布的电连接器绝缘可靠性建模

Modeling of the Signal Transmission of a Coaxial Connector With a Degraded Dielectric Layer in a Humid Environment

Radio frequency coaxial connectors are key components in circuits for signal transmission and directly influence the stability of communication systems. It is well known that connectors operating in harsh environments for extended periods are subject to physical degradation, which may lead to deterioration of signal integrity and overall communication quality. However, little work has been done with regard to connector dielectric degradation in humid environments. In this current work, the specific effects of connector dielectric degradation in humid environments on signal transmission are studied by theoretical and experimental analysis. Both a 3-D electromagnetic field model and an equivalent circuit model for connectors before and after degradation are developed in order to evaluate signal reflection and transmission loss. The results of these two models are compared and show good agreement. In addition, based on the material properties of the connector dielectric, the equivalent dielectric layer of a degraded connector is considered to consist of a double-layer dielectric structure composed of polytetrafluoroethylene (PTFE) and a layer of water film. The equivalent dielectric constant and equivalent loss tangent of the double-layer dielectric structure are calculated and analyzed. A corresponding equivalent circuit is developed consisting of an impedance network with resistance and capacitance elements in parallel. Experiment tests are conducted to validate the electromagnetic field model and the circuit model results. The results of this research provide a better understanding of the electrical characteristics of degraded connectors in humid environments and theoretical support for engineering applications.

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.

PEMBERDAYAAN GENERASI MILENIAL MELALUI KERAJIANAN TANGAN MERAJUT UNTUK MENINGKATKAN PENDAPATAN PADA MASA PANDEMI COVID 19

The COVID-19 pandemic has had an impact on all fields, including the family economy. The purpose of service activities is to carry out a community assistance process to recognize and make knitting skills, and produce products that can be marketed to improve the economy of the community. This service activity is carried out in three ways, namely training, implementation and mentoring. The subject of this service activity is the Youth of Kotangan Village, Galang District, Kab. Deli Serdang. The results of this activity include two things, first, the partner community has increased in terms of knowledge, understanding and skills in and the achievement of increased partner skills in the form of knitted bag models, cap models, mask connector models, as well as hats and skullcaps. Second, the products that have been produced have begun to be marketed through online media in Deli Serdang Regency. The achievement of this service activity is very dependent on the consistency of the partner's spirit to work during this pandemic.

A dual wideband high gain 2 × 2 multiple‐input‐multiple‐output monopole antenna with an end‐launch connector model for 5G millimeter‐wave mobile applications

This article presents the design, analysis, and realization of a new printed multiple-input-multiple-output (MIMO) antenna with a very high gain and wide bandwidth for the millimeter-wave (mm-wave) 28/38 GHz fifth generation (5G) new radio (NR) applications. The proposed MIMO antenna consists of four identical patch elements in a 2 × 2 configuration to achieve high gain with wide operating bandwidth. The proposed antenna holds an attractive compact size of 31.891 × 37.528 mm2. The proposed MIMO configuration is designed on a 0.508 mm thick Rogers-5870 substrate material with a loss tangent of 0.0009 and a relative dielectric constant of 2.33. An effective technique for folding the feed line and applying a new protruding ground is introduced to obtain good mutual coupling. The fabricated prototype of the proposed antenna is tested to verify the simulation results for the validation of the suggested design approach. The suggested MIMO antenna exhibits −10 dB impedance bandwidth of 2.6 GHz (27.4–30.0 GHz) and 3.3 GHz (36.7–40.0 GHz) to cover the intended frequency range for 5G applications with isolation less than −22 band peak gains of 18 and 14.5 dBi at 27.5 and 38.8 GHz, respectively. To validate the MIMO performance of the proposed antenna several MIMO diversity parameters such as mean effective gain (MEG), envelope correlation coefficient (ECC), and diversity gain (DG) are evaluated. Determined results indicate ECC < 0.001, DG > 9.995, and an average MEG of −3 dB at the operating bands. The proposed antenna exhibits good agreement between the simulated and measured results, which confirm its suitability for forthcoming mm-wave 5G MIMO systems and services.

Timed protocol analysis of interconnected mobile IoT devices

With the emergence of the Internet of Things (IoT), application developers can rely on a variety of protocols and Application Programming Interfaces (APIs) to support data exchange between IoT devices. However, this may result in highly heterogeneous IoT interactions in terms of both functional and non-functional semantics. To map between heterogeneous functional semantics, middleware connectors can be utilized to interconnect IoT devices via bridging mechanisms. In this paper, we make use of the Data eXchange (DeX) connector model that enables interoperability among heterogeneous IoT devices. DeX interactions, including synchronous, asynchronous and streaming, rely on generic post and get primitives to represent IoT device behaviors with varying space/time coupling. Nevertheless, non-functional time semantics of IoT interactions such as data availability/validity, intermittent connectivity and application processing time, can severely affect response times and success rates of DeX interactions. We introduce timing parameters for time semantics to enhance the DeX API. The new DeX API enables the mapping of both functional and time semantics of DeX interactions. By precisely studying these timing parameters using timed automata models, we verify conditions for successful interactions with DeX connectors. Furthermore, we statistically analyze through simulations the effect of varying timing parameters to ensure higher probabilities of successful interactions. Simulation experiments are compared with experiments run on the DeX Mediators (DeXM) framework to evaluate the accuracy of the results. This work can provide application developers with precise design time information when setting these timing parameters in order to ensure accurate runtime behavior.