Aluminum Connections Research Articles

Model-Based Damage Localization Using the Particle Swarm Optimization Algorithm and Dynamic Time Wrapping for Pattern Recreation.

Vibration-based damage detection methods are a subcategory of Structural Health Monitoring (SHM) methods that rely on the fact that structural damage will affect the dynamic characteristic of a structure. The presented methodology uses Finite Element Models coupled with a metaheuristic optimization algorithm in order to locate the damage in a structure. The search domains of the optimization algorithm are the variables that control a parametric area, which is inserted into the FE model. During the optimization procedure, this area changes location, stiffness, and mass to simulate the effect of the physical damage. The final output is a damaged FE model which can approximate the dynamic response of the damaged structure and indicate the damaged area. For the current implementation of this Damage Detection Framework, the Particle Swarm Optimization algorithm is used. As an effective metric of the comparison between the FE model and the experimental structure, Transmittance Functions (TF) are used that require output only acceleration signals. As with most model-based methods, a common concern is the modeling error and how this can be surpassed. For this reason, the Dynamic Time Wrapping (DTW) algorithm is applied. When damage occurs in a structure it creates some differences between the Transmittance Functions (TF) of the healthy and the damaged state. With the use of DTW, the damaged pattern is recreated around the TF of the FE model, while creating the same differences and, thus, minimizing the modeling error. The effectiveness of the proposed methodology is tested on a small truss structure that consists of Carbon-Fiber Reinforced Polymer (CFRP) filament wound beams and aluminum connectors, where four cases are examined with the damage to be located on the composite material.

A Review of the Friction Stir Welding of Dissimilar Materials between Aluminum Alloys and Copper

With the rapid development of various industries, the connection of copper and aluminum is in high demand. However, as a solid-phase connection technology, friction stir welding has a potential application prospect in the connection of copper and aluminum. This paper comprehensively summarizes the most recent 20 years of the literature related to the friction stir welding of copper and aluminum. The application significance of copper and aluminum connectors is introduced, and the research field of the friction stir welding of copper and aluminum is analyzed and explored from the aspects of welding technology, microstructure and mechanical properties, as well as innovations and improvements in the welding process. In view of the research status of this field, the authors put forward their views and prospects for its future, aiming to provide a basis for researchers in this field.

Failure Analysis of an Aluminum Earphone Connector due to Corrosion

Earphones are often exported to foreign countries by sea as consumer goods. In view of the humid marine environment, the earphone packaging box is often placed with anti-mold chips to prevent mold, while the volatilization of the anti-mold chips will also cause corrosion problems. In this study, a large number of aluminum earphone connectors were corroded in the process of ocean transportation, and the corrosion products were located in the left earphone connector close to the anti-mold chips. It’s determined that sulfate and nitrate ions lead to the corrosion of the aluminum connectors, and these are the volatilization products of the anti-mold chips. This conclusion was further confirmed by the simulation test, which was carried out on the anti-mold chips and aluminum connectors at 85 °C, 85% RH humidity for 72 h. The aluminum connectors were obviously corroded, and the morphology and composition of the corrosion products were the same as those on the actual earphones. The corrosion was successfully prevented by a PTFE coating on the surface of aluminum connectors. Keywords: Earphones; Anti-mold chip; Aluminum; Corrosion; PTFE coating

Experimental Study of the Corona Performance of Aged Sand-Cast Substation Connectors

Substation connectors, like many other high-voltage products, are tested once manufactured. However, the corona behavior of aged specimens can differ from that exhibited by newer ones, thus generating detrimental technical and environmental effects. Manufacturers need to know the long-term corona behavior of substation connectors to offer their customers maximum safety and transparency about such critical products. This paper analyzes the ageing effect on the surface roughness and the visual corona extinction voltage of sand-cast aluminum connectors, which were artificially aged in a salt spray chamber for different periods. The experimental results show an important variability of the surface roughness and corona extinction voltage (CEV) among connectors with the same ageing level due to the sand-casting manufacturing process. The results in this paper also show a slight increase in the surface roughness with the ageing period, although there is not a clear pattern between the applied ageing level and the experimental CEV value. It is concluded that the inherent variability among connectors due to the sand-cast process has more influence than the ageing effect itself.

Performance and Diagnosis of Aluminum Connectors Tested Inside MV Cable Splices

Performance of power cable connectors is usually evaluated under bare conditions as for overhead applications, such as specified in the test standards ANSI C119.4 and IEC 61238-1. Significant differences exist between the requirements of these two standards, in particular, the short-circuit current test that only becomes optional in the recent ANSI 2011 edition. Furthermore, past and recent experience with testing medium-voltage cable splices according to the standard IEEE 404 have revealed the shortcoming of the aluminum connectors tested on aluminum conductors with overheating failure. New mechanical power connectors on the market offering range-taking capability and easy installation promise better connectivity and reproducibility based on the shear-bolt technology. This paper discusses the results as obtained in an accelerated aging test on different types of cable splices with both compression and mechanical connectors. Based on the test results, a simple and effective method is also proposed to identify a degraded connector inside a cable splice.

Shaking table testing of granite cladding with undercut bolt anchorage

To investigate the seismic performance of granite cladding with undercut bolt anchorage and aluminum connectors, shaking table testing of full-scale specimens was performed. The floor spectrum was constructed and its compatible floor motion time history was generated and used as the input motion. A stiff steel frame was designed to provide the floor earthquake excitation to the cladding specimens installing on its four sides. Experimental results show that the aluminum connectors are the most seismically vulnerable components of the cladding system. The excessive relative in-plane sliding of the two-parts of the aluminum connectors governs the seismic performance of the whole system. While the out-of-plane deformation of the connectors absorbs part of the dynamic energy passed from the steel frame, which reduces the potential damage to the granite panels. The largest component acceleration amplification factor was determined to be about 2.9, which is larger than the recommended values in the current code provisions. Moreover, the experimentally estimated peak bending stress exceeded the design value. Finally, the seismic performance levels of the cladding were quantified and the corresponding fragility curves were also developed.

The robustness of carbon fibre members bonded to aluminium connectors in aerial delivery systems

AbstractIn this paper a framework for robust design solution of an adhesively bonded joint between a composite material and an aluminum connector is developed. To this end, an approach has been developed to automate the process of robust design by linking Ansys workbench and an in-house MATLAB code. The model employed in this study investigated the possibility of joining composite materials to aluminum components which is a problematic process in terms of preparation, implementation, etc. Before designing such a join, it is necessary to fully understand the behaviour of the proposed aluminum connector with the carbon fibre member. To achieve this, the investigation of the adhesive layer’s behaviour and the uncertainties involved in such structures was identified. The behaviour of the adhesive between the carbon fibre composite and the aluminum connector was modelled based on the assumption that this layer acts as a “spring system” within a “cohesive” zone. Initially, the properties of Permabond ET5428 BLA...

A novel strengthening method for carbon fiber composite lattice truss structures

The composite pyramidal lattice truss core sandwich panel, in which the lattice core is strengthened by end frames between various nodes and the struts are reinforced with unidirectional fibers, is fabricated by the hot-press molding technique and interlocking method. Because all of the continuous fibers are aligned in the rod direction, the fiber’s intrinsic strength can be fully exploited; thus, the lattice truss core has the maximum load-carrying capacity. Furthermore, the composite lattice truss core (strengthened by the top and bottom aluminum connectors) has the ability to collaboratively deform under compressive and shear loading. Compressive and shear experiments were conducted to investigate the mechanical properties and failure mechanism of this new composite pyramidal lattice structure. The experimental results show that the present composite pyramidal lattice structure has some significant advantages compared with other existing composite pyramidal lattice structures.

긴급시공이 가능한 FRP 내진보강재 개발 및 최적 보강량 산정을 위한 해석적 연구

Social interest in the seismic retrofit of the structure is growing massive earthquake that occurred recently. The brittle fracture of Non-seismically designed Columns lead to full collapse of the building. In the past, cross-sectional expansion method, a steel plate reinforcing method is applied mainly in recent years, fiber-reinforced method utilizing the advantages of the composite material are preferred. However, the reinforcement methods such as this, there is a drawback to induce physical damage to structures, and time consuming work space is large. IIn this study, FRP seismic reinforcement was developed using the Aluminum connector and the composite material (Glass Fiber Reinforced Polymer). Then, the optimum quantities of FRP seismic reinforcement was determined using a nonlinear finite element analysis program. Finally, the quantity decision process through the design and analysis of FRP reinforcement was suggested.

Determining Individual Stresses Throughout a Pinned Aluminum Joint by Reflective Photoelasticity

Pinned (bolted) joints are an extremely important, but difficult to analyze, structural or mechanical element. They are a class of inverse problems in which the stresses at the pin/hole interface are typically unknown. Moreover, stresses vary non-linearly with applied load. Failures of mechanical or structural systems frequently initiate at connections. Although almost always present, many stress analyses of such mechanical connections ignore friction for simplicity. The stresses are evaluated here in an aluminum connector using a series solution of an Airy stress function, the coefficients being evaluated from known boundary tractions (near, but not including the contact region on the hole) and photoelastically measured data obtained from a bonded birefringent coating. Both friction and pin/hole clearance are accounted for, and individual stresses are evaluated full-field, including on the contact boundary of the hole.

Comparative Corrosion and Current Burst Testing of Copper and Aluminum Electrical Power Connectors

Crimped and mechanically bolted aluminum and copper connectors are commonly used for terminating industrial electrical power cables with ratings up to 600 V. Aluminum connectors are available for use with aluminum or copper conductor, and copper connectors are available for use with copper conductor only. The performance of copper and aluminum connectors was compared by conducting accelerated aging under corrosive environmental conditions. The testing consisted of 2000 hours of cyclic salt fog environmental exposure, in conjunction with periodic electrical current burst testing. The connectors were evaluated by comparing the change in resistance of the test samples as the test progressed.

Thermally Induced Mechanical Degradation of Contact Spots in Aluminum Interfaces

Deterioration of an electric contact is closely related to phenomena occurring in the microscopic contact spots in the contact interface. Contact spots in idealized aluminum-aluminum contact interfaces, that have passed heavy alternating currents, have been carefully examined by scanning electron microscopy and metallographic imaging techniques. Small cracks are observed in the contact spot regions, and have to a great extent impaired the current-carrying ability of the area. The temperature in the contact spots cycles with twice the power frequency, and in heavily stressed contacts the maximum temperature reaches several hundred degrees centigrade. The associated local thermal expansion and contraction in and around the immediate vicinity of the contact spot generates cyclic mechanical forces of substantial magnitudes. Indications that this repetitive stress causes the observed cracks are found. It is suggested that the resistance increase observed in practical aluminum connectors being subjected to short-circuit currents can have a similar origin

A planar unimorph-based actuator with large vertical displacement capability. I. Experiment

A piezoelectric actuator utilizing a planar arrangement of unimorph elements that produces displacements perpendicular to the plane of the actuator is described. The elements are connected in series mechanically so that the vertical displacement of each element adds to the vertical displacements of the other elements. Two prototype actuators were built and tested. One was stick-built from individual bars of PZT and aluminum, which were epoxied together and connected to each other with short aluminum connector bars. The other was fabricated monolithically from a single plate of PZT by bead-blasting the PZT plate through a steel shadowmask to mill out the desired actuator shape. Copper bars epoxied to the milled-out PZT bars then formed the unimorph elements. The unloaded output displacement of each actuator versus applied voltage was measured as well as the displacement versus applied force with no applied voltage. These measurements were in agreement with the predictions of an electromechanical model of the actuator that has been developed. The model predicted and measurements verified that stiffeners can be added to the basic geometry that will significantly increase the force output without affecting the displacement versus applied voltage characteristic.

An Efficient 2D Finite Element Procedure for the Quenching Analysis With Phase Change

An efficient finite element procedure has been developed for the analysis of quenching problems involving nonisothermal phase changes. The finite element analysis includes temperature dependent material properties, a mixed hardening rule to describe the material constitutive model, and the incorporation of time-temperature-transformation (TTT) diagrams. The procedure is applied to the simulation of quenching of steel cylinders and an aluminum connector with temperature-dependent convection boundary conditions. First, the stress analysis of the quenching of an infinite cylinder is carried out and the predicted distributions of temperature and stresses are compared with an available numerical solution to validate the accuracy of the present formulation and procedure. To demonstrate the predictive capability and practical applicability of the developed procedure, the simulation of quenching of finite cylinders of various length-to-diameter ratios and of a square bar are presented. The role of edge effects and specimen geometry on the residual stress distribution is analyzed. In addition, the microstructures developed during the quenching of 1080 carbon steel cylinders are predicted using TTT diagram incorporated in the analysis. The final example addresses the simulation of age hardening in spray quenched 2024 aluminum connector. The example problems are directly related to many practical applications, such as the heat-treatment of solid piston pins used in automotive engines and the spray quenching of aluminum connector. They also illustrate the wide range of material transformations which can be modeled using the present finite element procedure.

Fretting damage in tin-plated aluminum and copper connectors

A number of bolted-type tin-plated aluminum and copper connectors commonly used for distribution transformers were examined using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), Auger electron spectroscopy (AES), X-ray analysis, and optical microscopy. In addition, the contact resistance of the connector contact zones was measured using a point probe. The connectors studied had been removed from service because of unsatisfactory performance under normal operating conditions as manifested either by overheating or instability. The results of the detailed examination show the presence of extensive fretting damage in the contacting surfaces. The fretting debris was composed mainly of tin oxide and oxidized base metal particles. Localized melting and wear of the tin plating down to the underlying substrate were also observed in some of the connectors examined. >

Failure and Overheating of Aluminum-Wired Twist-On Connections

In this investigation, twist-on connectors of the type used for branch circuit wiring in buildings have been tested with solid aluminum and copper conductors. The connector and conductor combinations tested are approved in both the United States and Canada. All of the twist-on connections were made in accordance with the connector manufacturers' instructions. Testing consisted of on-off cycling at 90 percent of rated current and 13 percent duty cycle. Failures, involving increasing connection resistance and abnormal heating, have occurred in less than a year in a substantial number of the aluminum-wired connections. The failures involve both the electrical conductor (EC) and alloy aluminum conductors. In contrast the copper-wired connections have low resistance and are stable. The temperature of many of the overheating aluminum-wired connections has been high enough to cause hazardous deterioration of the conductor insulation. The difference in performance between the copper and aluminum conductors is determined to be due to failure to achieve and sustain low resistance conductor-to-conductor contact in the aluminum-wired connections. This results in the greater portion of the current flowing through the connector spring rather than directly from conductor to conductor. The connector spring is plated steel and is not suited to be the major part of the current path. Degradation of the contacts between the aluminum wires and connector spring follows by several well-known mechanisms, leading to increasing connection resistance and the resulting heat generation and high temperatures.

Nontension Aluminum Connectors [includes discussion

Nontension Aluminum Connectors [includes discussion