Interference-Fit Joining of Aluminium Tubes by Electromagnetic Forming

2013 ◽  
Vol 853 ◽  
pp. 488-493 ◽  
Author(s):  
M. Geier ◽  
M.M. José ◽  
R. Rossi ◽  
P.A.R. Rosa ◽  
P.A.F. Martins
Keyword(s):  
Room Temperature ◽  
New Technologies ◽  
Failure Mechanisms ◽  
Dissimilar Materials ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Electromagnetic Forming ◽  
Interference Fit ◽  
Structural Adhesives ◽  
New Applications

Interference-fit joining of tubes by electromagnetic forming is an innovative and environmental friendly technology that can successfully replace conventional joining technologies based on fasteners, structural adhesives, welding and brazing. The technology works at room temperature, allows joining dissimilar materials and offers potential to foster new applications in the assembly of lightweight tubular frame structures. As with all new technologies, there is a need to understand interference-fit joining of tubes by electromagnetic forming in terms of its major parameters with the aim of identifying their influence on the overall strength of the joints and establishing the useful range of process operating conditions. This article investigates the interference-fit joining of aluminum-alloy tubes (AA6082-O) with mandrels made from different metallic and polymeric materials (AA6082-O, AISI1045 and Erlaton 6SA). Results show that the strength of the joint and the associated failure mechanisms are directly related to process parameters and materials.

Joining of Tubular Parts by Electromagnetic Forming; Experimental Investigations

2014 ◽  
Vol 792 ◽  
pp. 115-120 ◽  
Author(s):  
Pál Rácz ◽  
Nándor Göbl ◽  
Daniel Horváth ◽  
Athanasios G. Mamalis
Keyword(s):  
High Speed ◽  
New Technologies ◽  
Dissimilar Materials ◽  
High Energy ◽  
Mechanical Tests ◽  
Electromagnetic Forming ◽  
High Energy Density ◽  
Experimental Investigations ◽  
Forming Process ◽  
High Speed Forming

Electromagnetic forming is a high speed forming process, wherein the forming pressure is created by high energy density electromagnetic pulse. Besides direct shaping there are other application areas as well, so electromagnetic plastic forming is a potential field of creating joints between tube and rod-like components. Connecting components of dissimilar materials is an increasing demand in the manufacturing process of structures in the automotive industry. The application of new technologies, such as electrodynamic, especially electromagnetic forming, is a possible method to satisfy these demands. The article summarizes the most important fundamentals of electromagnetic forming; in particular, tube-rod joints, the main types of such joints; interference-fit and form-fit joints are described. Experiments, which were carried out producing tube-rod joints with electromagnetic forming, are also introduced. A new type of form-fit joints for tube-rod connections has been developed, which can withstand not only tensile loads but also torsion. Experiments and mechanical tests have proved the applicability of this kind of joints.

Reliability of Manganese Dioxide and Conductive Polymer Tantalum Capacitors under Temperature Humidity Bias Testing

2015 ◽  
Vol 2015 (1) ◽  
pp. 000713-000719 ◽  
Author(s):  
Anto Peter ◽  
Michael H. Azarian ◽  
Michael Pecht
Keyword(s):  
Manganese Dioxide ◽  
Room Temperature ◽  
Failure Mechanisms ◽  
Conductive Polymer ◽  
Operating Conditions ◽  
Leakage Currents ◽  
Test Population ◽  
Polymer Electrodes ◽  
Surge Current

Despite being highly reliable under steady state operating conditions, manganese dioxide (MnO2) tantalum capacitors are prone to catastrophic exothermic failures under surge current conditions. Such failures can be mitigated by the use of conductive polymers in place of MnO2. However, these polymers are more susceptible to failure at elevated humidity levels. In this paper, the electrical performances of both MnO2 and polymer tantalum capacitors are compared by subjecting them to temperature humidity bias testing at 85°C and 85% RH. The test population consists of tantalum capacitors with two voltage ratings (50V and 16V). At each of these voltage ratings, two sets of tantalum capacitors, one each with MnO2 and conductive polymer electrodes, were tested. The voltage levels used to bias the capacitors were periodically increased in multiples of the rated voltage to accelerate degradation. The performance of the capacitors was tracked by monitoring their capacitance, dissipation factors and leakage currents, both in-situ and at room temperature. The degradation trends are discussed in light of the differences in voltage ratings and electrode types. These trends are also mapped to fundamental failure mechanisms within the capacitors.

scholarly journals Investigation of Fatigue Behavior of ABS and PC-ABS Polymers at Different Temperatures

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1818
Author(s):  
Andrea Mura ◽  
Alessando Ricci ◽  
Giancarlo Canavese
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Working Condition ◽  
Fatigue Behavior ◽  
Polymeric Materials ◽  
Cyclic Loads ◽  
Structural Components ◽  
Working Temperature ◽  
Different Temperatures ◽  
Positive Effect

Plastics are widely used in structural components where cyclic loads may cause fatigue failure. In particular, in some applications such as in vehicles, the working temperature may change and therefore the strength of the polymeric materials. In this work, the fatigue behavior of two thermoplastic materials (ABS and PC-ABS) at different temperatures has been investigated. In particular, three temperatures have been considered representing the working condition at room temperature, at low temperature (winter conditions), and high temperature (summer conditions and/or components close to the engine). Results show that high temperature have big impact on fatigue performance, while low temperatures may also have a slight positive effect.

scholarly journals Setting the Optimal Laser Power for Sustainable Powder Bed Fusion Processing of Elastomeric Polyesters: A Combined Experimental and Theoretical Study

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 385
Author(s):  
Ruben Vande Ryse ◽  
Mariya Edeleva ◽  
Ortwijn Van Stichel ◽  
Dagmar R. D’hooge ◽  
Frederik Pille ◽  
...  
Keyword(s):  
Laser Power ◽  
Theoretical Study ◽  
Selective Laser Sintering ◽  
Polymeric Materials ◽  
Thermoplastic Elastomer ◽  
Processing Parameters ◽  
Operating Conditions ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Bed Temperature

Additive manufacturing (AM) of polymeric materials offers many benefits, from rapid prototyping to the production of end-use material parts. Powder bed fusion (PBF), more specifically selective laser sintering (SLS), is a very promising AM technology. However, up until now, most SLS research has been directed toward polyamide powders. In addition, only basic models have been put forward that are less directed to the identification of the most suited operating conditions in a sustainable production context. In the present combined experimental and theoretical study, the impacts of several SLS processing parameters (e.g., laser power, part bed temperature, and layer thickness) are investigated for a thermoplastic elastomer polyester by means of colorimetric, morphological, physical, and mechanical analysis of the printed parts. It is shown that an optimal SLS processing window exists in which the printed polyester material presents a higher density and better mechanical properties as well as a low yellowing index, specifically upon using a laser power of 17–20 W. It is further highlighted that the current models are not accurate enough at predicting the laser power at which thermal degradation occurs. Updated and more fundamental equations are therefore proposed, and guidelines are formulated to better assess the laser power for degradation and the maximal temperature achieved during sintering. This is performed by employing the reflection and absorbance of the laser light and taking into account the particle size distribution of the powder material.

scholarly journals Physicochemical characteristics of solid particles of contaminants in the coolant of automobile and tractor engines

2021 ◽  
Vol 1 (3) ◽  
pp. 53-61
Author(s):  
S.G. Dragomirov ◽  
◽  
P.Ig. Eydel ◽  
A.Yu. Gamayunov ◽  
M.S. Dragomirov ◽  
...  
Keyword(s):  
High Performance ◽  
Cooling System ◽  
Chemical Elements ◽  
Dissimilar Materials ◽  
Physicochemical Characteristics ◽  
Operating Conditions ◽  
Solid Particles ◽  
Physicochemical Interaction ◽  
Cooling Systems ◽  
Thin Oxide Film

The article describes the results of a study of the physicochemical characteristics of solid particles of contaminants present in the coolant of automobile and tractor engines. The data on the fractional, physical and chemical composition of solid particles of contamination are given. It was established that the generalized reason for the appearance of contaminants of various nature in liquid cooling systems of engines is the physicochemical interaction of the coolant (antifreeze) with different elements and dissimilar materials of the cooling system. The use of absolutely pure coolant in the cooling systems of automobile and tractor engines is practically unrealistic, since there will always be operating conditions that contribute to the formation of contamination. A number of chemical elements (in an amount from 1 to 47% of each element) were found in the composition of solid particles of coolant contaminants: iron Fe, silicon Si, aluminum Al, lead Pb, tin Sn, zinc Zn, calcium Ca, magnesium Mg, copper Cu. In addition, at a level of less than 1.0% (wt.), Such chemical elements as potassium K, sodium Na, titanium Ti, phosphorus P, sulfur S, chromium Cr, molyb-denum Mo, chlorine Cl, iridium Ir, nickel Ni, manganese Mn, etc. were found. The most dangerous contaminants are particles of iron Fe and silicon Si, contained in the coolant in an amount of up to 47 and 37%, respectively, and possessing significant hardness and angularity. The abrasive proper-ties of Fe and Si particles create the danger of removing a thin oxide film on the inner surface of the walls of the cooling radiator channels, leading to their premature destruction. In this regard, it is concluded that high-performance engine coolant filters should be used in automobiles and tractors to remove these contaminants from the flow.

scholarly journals Voltage Unbalance Effect on the Behavior of IE2, IE3 And IE4 Induction Motor Classes

2021 ◽  
Author(s):  
Jonathan M. Tabora ◽  
Edson O. de Matos ◽  
Thiago M. Soares ◽  
Maria Emília De L. Tostes
Keyword(s):  
Induction Motor ◽  
Motor Performance ◽  
New Technologies ◽  
Operating Conditions ◽  
Electric Motors ◽  
Voltage Unbalance ◽  
Squirrel Cage ◽  
Squirrel Cage Induction Motor ◽  
Cage Induction Motor ◽  
Hybrid Motor

More than 30 million electric motors are sold every year in the world, in the last 20 years the appearance of more efficient electric motors resulted in the replacement of more than 70% of the old motors installed. New technologies are being presented by manufacturers as substitutes for the squirrel cage induction motor (SCIM). Given this scenario, studies should be carried out to analyze the performance of these motors in the same operating conditions to know their main advantages and drawbacks. This study presents a comparison of the performance of electric motors classes IE2, IE3 and IE4 in the presence of voltage unbalance (VU) with under and over voltage. Results show that not only the unbalance percentage present impacts the motor performance, but also the magnitudes of the voltages present. The VU also results in an increase in the harmonics present in each motor, mainly in the permanent magnet hybrid motor, which presents non-linear characteristics.

scholarly journals Internal donors on supported Ziegler Natta catalysts for isotactic polypropylene: a brief tutorial review

2021 ◽  
Vol 28 (10) ◽  
Author(s):  
Bharat R. Paghadar ◽  
J. B. Sainani ◽  
Samith K. M. ◽  
Poornima Bhagavath
Keyword(s):  
Polymeric Materials ◽  
Detailed Comparison ◽  
Short Review ◽  
Point Of View ◽  
Polymer Science ◽  
Cross Combination ◽  
Polymer Properties ◽  
Technical Advances ◽  
Catalyst Systems ◽  
New Applications

AbstractThe scientific and technical advances in the field of polymer science has been abundant in recent years. Amongst the various polymeric materials available in market, synthesis of polyolefins has been in the forefront since decades. A major challenge in this domain remains in attaining stereoregular polyolefins especially polypropylene (PP) and significant efforts were carried out by synthesizing various internal donors (ID) aiding the catalysts involved in producing them. This short review gives an overview of i) various generations of Ziegler–Natta (ZN) catalyst systems ii) general classes of ID that has been demonstrated by the researchers over the past decades iii) their influence on PP isotacticity and polymer properties. The coordination modes of different donor classes on supported ZN system and comparative study especially between phthalate and diether ID classes were also addressed here. This review also presents the studies carried out on phthalate catalyst structure analysis, detailed comparison study on phthalate and diether IDs in terms of PP isotacticity, regioselectivity, hydrogen response, and also their cross combination study and competitive behavior. Further a brief description on other structurally varied IDs like malonates, maleates, silyl diol esters, bifunctional donors, multi ether donors demonstrated for isotactic PP were also presented. Studies conducted on compatibility of incorporation of two different classes of IDs on a single supported ZN system for the fundamental understanding of the catalyst behavior; and also on how mixed donor approach enables in tuning the catalyst for polymer properties were also presented. This review also provides an opportunity to the young minds and the basic researchers from academic point of view by and large to create new polymeric materials with useful properties or modify the existing materials for new applications by incorporating new IDs for further improvisation of the stereo regularity in obtaining the polymers. Graphic Abstract

Evolution of Sintering of Particles that Compose Iron Ore Agglomerates

2017 ◽  
Vol 899 ◽  
pp. 371-376
Author(s):  
Flavia de Paula Vitoretti ◽  
Maria Carolina dos Santos Freitas ◽  
Camila Martins Hosken ◽  
Jose Adilson de Castro ◽  
Fabiane Roberta Freitas da Silva
Keyword(s):  
Iron Ore ◽  
Room Temperature ◽  
New Technologies ◽  
Microstructural Characterization ◽  
Sintering Process ◽  
Iron Ore Pellets ◽  
Ore Pellets ◽  
Reduction Of Iron ◽  
Increasing Demand ◽  
Metallurgical Characterization

The increasing demand for new technologies in the ironmaking/steelmaking field has been motivating several studies towards pelletizing process improvement. Within this context, evaluate the reduction of iron ore pellets using the dilatometer technique constitutes a promising approach for optimizing this process. This paper aims the metallurgical characterization through the sintering of particles in iron ore pellets. With this purpose, some experimental procedures are of concern as follows. Firstly, the kinetic densification of the iron ore pellets is measured using a dilatometer, which heats the samples up at 30 K/min until high temperatures about 1473 K and an isotherm at 10 minutes have been done. Then, the sample is cooled back to room temperature and undergoes a microstructural characterization, with the aid of a scanning electron microscope. At last, the density of the pellets is evaluated, using an Arquimedes Principle and consequently the porosity of the agglomerates. The results indicate the sintering progress of the particles that comprise the pellets as well as reduction the porosity. This behavior is due to the fact that the heat arising from gas induces the partial liquid phase formation and involves the agglomerate particles aiding in the sintering process.

A room-temperature self-healing elastomer with ultra-high strength and toughness fabricated via optimized hierarchical hydrogen-bonding interactions

2022 ◽  
Author(s):  
Liangliang Xia ◽  
Ming Zhou ◽  
Hongjun Tu ◽  
wen Zeng ◽  
xiaoling Yang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Polymeric Materials ◽  
High Strength ◽  
Self Healing ◽  
High Mechanical Strength ◽  
Hydrogen Bonding Interactions ◽  
Healing Efficiency ◽  
Good Healing

The preparation of room-temperature self-healing polymeric materials with good healing efficiency and high mechanical strength is challenging. Two processes are essential to realise the room-temperature self-healing of materials: (a) a...

Evaluation of Low Cost, High Temperature Die and Substrate Attach Materials for Silicon Carbide (SiC) Power Modules

2018 ◽  
Vol 2018 (1) ◽  
pp. 000317-000325
Author(s):  
Sayan Seal ◽  
Brandon Passmore ◽  
Brice McPherson
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Operating Conditions ◽  
Acoustic Microscopy ◽  
Switching Frequency ◽  
Power Devices ◽  
Formidable Challenge ◽  
Die Attach ◽  
Power Modules ◽  
High Switching Frequency

Abstract The performance of SiC power devices has demonstrated superior characteristics as compared to conventional Silicon (Si) devices. Some of the advantages of SiC power devices over Si include higher voltage blocking capability, low specific on-resistance, high switching frequency, high temperature operation, and high power density. Thus, SiC modules are capable of processing significant levels of power within much smaller volumes compared with its Si counterparts. These high thermal loads present a formidable challenge in integrating SiC devices in power modules. For example, known-good materials and processes for silicon power modules are not rated at the aggressive operating conditions associated with SiC devices. Two of the most critical interfaces in a power electronics module are the die-attach and substrate- attach. A degradation in these interfaces often results in potentially catastrophic electrical and thermal failure. Therefore, it is very important to thoroughly evaluate die-attach materials before implementing them in SiC power modules. This paper presents the methodology for the evaluation of die attach materials for SiC power modules. Preforms of a lead-free high-temperature attach material were used to perform a die and substrate attach process on a conventional power module platform. The initial attach quality was inspected using non- destructive methods consisting of acoustic microscopy and x-ray scanning. Die attach and substrate attach voiding of < 5% was obtained indicating a very good attach quality. Cross-sectioning techniques were used to validate the inspection methods. The initial attach strength was measured using pull tests and shear tests. The measurements were repeated at the rated temperature of the module to ensure that the properties did not degrade excessively at the service temperature. At the rated module temperature of 175 °C, the die bonding strength was found to be ~ 75 kg. This was only 25% lower than the strength at room temperature. In addition, the contact pull strength was measured to be > 90 kg at 175 °C, which was 25% lower than the value measured at room temperature. The effect of power cycling and thermal cycling on the quality and strength of the die and substrate attach layers was also investigated.

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