scholarly journals Thermal Efficiency in Laser-Assisted Joining of Polymer–Metal Composites

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4875
Author(s):  
Klaus Schricker ◽  
Mohammad Alhomsi ◽  
Jean Pierre Bergmann
Keyword(s):  
Thermal Efficiency ◽  
Unit Length ◽  
Polyamide 6 ◽  
General Description ◽  
Dimensionless Numbers ◽  
Aisi 304 ◽  
Polymer Metal ◽  
Physical Background ◽  
Polyamide 6.6

Heat conduction joining is mainly used in laser-based joining of metals with polymers but results in a large amount of dissipated heat. The consideration of thermal efficiency allows the determination of power actually used for creating the joint, which is highly relevant for technical and economic reasons, e.g., for calculating the carbon footprint. In order to describe the thermal efficiency universally, process parameters (focal diameter, joining speed, energy per unit length), metallic materials (AA 6082, AISI 304), geometric parameters (overlap width, material thickness) and various polymers (polypropylene, polyamide 6, polyamide 6.6) were examined experimentally. The discussion of the results is supplemented by numerical simulations of the temperature field. For a general description of the physical relationships, some dimensionless numbers based on the Buckingham π theorem were developed, applied to the experimental data. One of these numbers shows similarity to the Fourier number and provides further information on thermal efficiency and its general understanding in the context of polymer–metal joints, enabling the physical background dissipated to stored heat.

Determination of the propagation state of the combustion zone during in-situ combustion by dimensionless numbers

Fuel ◽  
2021 ◽  
Vol 284 ◽  
pp. 118972
Author(s):  
Dong Liu ◽  
Junshi Tang ◽  
Ruonan Zheng ◽  
Qiang Song
Keyword(s):  
Combustion Zone ◽  
Dimensionless Numbers ◽  
In Situ Combustion

Fatigue behaviour of material-adapted fibre-reinforced polymer/metal joints

2021 ◽  
Vol 3 (1) ◽  
pp. 81-88
Author(s):  
Colin Gerstenberger ◽  
Tomasz Osiecki ◽  
Lothar Kroll
Keyword(s):  
Polyamide 6 ◽  
Fatigue Behaviour ◽  
High Yield ◽  
Cold Forming ◽  
Shear Loads ◽  
Polymer Metal ◽  
Lightweight Engineering ◽  
Micro Alloyed Steel ◽  
Reinforced Thermoplastics ◽  
Cross Tension

By regarding the needs and requirements in modern multi-material joining, the Flow Drill Joining Concept (FDJ) was developed at the Chemnitz University of Technology. The technology allows an efficient and material-adapted joining of thin metal sheets with continuous fibre-reinforced thermoplastics, as required in modern lightweight engineering. For a better understanding of their fatigue behaviour, single-lap FDJ joints were examined in quasi-static and dynamic tests regarding shear loads, cross tension and superimposed shear/cross tension loads. By way of example, joints between micro-alloyed steel with high yield strength for cold forming and a continuous glass/carbon fibre-reinforced polyamide 6 were investigated. The fatigue curves show inclinations between k = 8.01 (shear loads) and k = 5.17 (cross tension loads), depending on the applied load angle. The results of the fatigue testings represent a basis for the enhancement of a failure criterion for FRP/metal joints in highly stressed multi-material designs.

scholarly journals What are the Main Sensor Methods for Quantifying Pesticides in Agricultural Activities? A Review

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2659 ◽  
Author(s):  
Roy Zamora-Sequeira ◽  
Ricardo Starbird-Pérez ◽  
Oscar Rojas-Carillo ◽  
Seiling Vargas-Villalobos
Keyword(s):  
Detection Limit ◽  
Crop Production ◽  
Fruits And Vegetables ◽  
Extended Period ◽  
Pesticide Use ◽  
General Description ◽  
Agricultural Activities ◽  
Agricultural Pesticides ◽  
Sensitivity And Selectivity

In recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description of recent advances in the development of methods for the quantification of pesticides used in agricultural activities. Current advances focus on improving sensitivity and selectivity through the use of nanomaterials in both sensor assemblies and new biosensors. In this study, we summarize the electrochemical, optical, nano-colorimetric, piezoelectric, chemo-luminescent and fluorescent techniques related to the determination of agricultural pesticides. A brief description of each method and its applications, detection limit, purpose—which is to efficiently determine pesticides—cost and precision are considered. The main crops that are assessed in this study are bananas, although other fruits and vegetables contaminated with pesticides are also mentioned. While many studies have assessed biosensors for the determination of pesticides, the research in this area needs to be expanded to allow for a balance between agricultural activities and environmental protection.

scholarly journals A new current weigher, and a determination of the electromotive force of the normal weston cadmium cell

1907 ◽  
Vol 80 (535) ◽  
pp. 12-18
Keyword(s):  
Current Sheet ◽  
Electromotive Force ◽  
Unit Length ◽  
Screw Thread ◽  
Late Professor ◽  
Convenient Formula ◽  
Association Meeting ◽  
Helical Current ◽  
Mutual Induction

The instrument described is the outcome of conversations between the late Professor J. Viriamu Jones, F. R. S., and one of the authors (W. E. A.), on their return from the British Association Meeting held in Toronto in 1897. Its object was to determine “ the ampere ” as defined in the C. G. S. system, to an accuracy comparable with that attained in the absolute determination of the ohm by Lorenz’s apparatus, an account of which was given by Professors Ayrton and Jones at the Toronto Meeting. Professor Jones had previously developed a convenient formula for calculating the electromagnetic force between a helical current and a coaxial current sheet, viz., F = γ h γ (M 2 -M 1 ),† where γ h is the current in the helix, the γ current per unit length of the current sheet, and M 1 , M 2 the coefficients of mutual induction of the helix and the two ends of the current sheet respectively. By using coaxial coils with single layers of wire wound in screw-thread grooves, advantage could be taken of the above formula.

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