Properties Of Seams Research Articles

Comparative Study on Pulsed Laser Welding Strategies for Contacting Lithium-Ion Batteries

The transition towards renewable energy implicates more decentralized and time-dependent ways of energy generation. In order to deal with the resulting fluctuation in energy supply, local storage systems are necessary. Larger systems may consist of thousands of battery cells. Therefore, the reliable interconnection between the individual battery cells is the basic prerequisite for the production of these systems. It has been demonstrated that laser beam welding is a suitable process for the contacting of batteries. However, due to the high requirements regarding the heat input and the reproducibility of the joining process, further investigations are necessary. Within this work, experiments on pulsed laser beam welding of nickel-plated DC04 steel were conducted. Four different pulsed welding strategies were analyzed in a preliminary study in order to develop a method for obtaining suitable process parameters while reducing the amount of free parameters. Subsequently, a comparative study between the rectangular pulse, the shaped pulse, the spike pulse and the sloping pulse was carried out. The weld seam properties as well as the electrical and the mechanical properties of the connection joints were evaluated. The results presented in this paper indicate a high eligibility of pulsed laser beam welding as a joining process for the connection of battery cells. For all analyzed pulsed welding strategies a homogeneous weld seam without full penetration was observed. Similar electrical resistances for all strategies were measured despite the comparatively small total joint area for the discretely pulsed weld seams.

Experimental study on physical structure properties and anisotropic cleat permeability estimation on coal cores from China

Knowledge of the natural structure properties of coal seams is essential for the coal bed methane (CBM) production because of their great influence on the inner flow characteristics and permeability features of hydrocarbons and water. In this paper, a series of laboratory tests, including nondestructive low-field nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray computed tomography (CT) and core tests were carried out to characterize the physical structure properties of coal. The pore size distribution, pore type, morphological features and three-dimensional rendering of coal cleat structures are presented. The permeability changes of 7 cylindrical coal cores investigated under a varying effective stress range (0–35Mpa) reveal that coal porosity decreased linearly and coal permeability declined exponentially with the rise of stress; while under higher stress conditions, the occurrence of internal crushing and mechanical damage will result in irreversible change for porosity and permeability. Through the comprehensive analysis based on linking permeability to porosity and CT result, a basic estimation on directional cleat permeability is also realized. This method provides a preliminary but satisfactory estimation for local directional cleat permeability, which reflects that both bedding and non-bedding direction permeability owns great heterogeneity for an individual sample; but face cleat permeability always found to be the largest, and the mean bedding plane permeability value is found usually 3.01–11.68 times lower than face and butt cleat permeability.

Seam properties of ultrasonic welded multilayered textile materials

This study examined the effects of ultrasonic welding parameters on bond strength, seam thickness and seam stiffness, as well as water permeability. For study purpose, two types of four-layered fabrics with same compositions and different areal densities suitable for inner part of sport shoes were used. Two different types of seams, lapped and superimposed, were applied for ultrasonic welding and also compared by traditional seam applied by shoe manufacturer. The morphology of different type of seams was also analyzed to observe the influence of welding parameters on the layers during the ultrasonic welding process. Bonding strength was found to depend on the seam type and composition of the joined fabric layers. It was confirmed by the shoe manufacturer that all the produced welded seams provided the requested minimum bond strength to be suitable for the use of the shoes. The traditional seams applied by the shoe manufacturer were thicker but had lower stiffness in comparison to all welded seams. It was also found out that ultrasonic welding damaged the membrane, which was confirmed by no water resistance of welded seams. Statistical analysis showed that ultrasonic welding parameters, such as welding frequency and velocity, influence the bond strength, thickness, and bending stiffness of welded seams, but the obtained results were statistically insignificant.

Characterization of weld seam properties of extruded magnesium hollow profiles

Extrusions of hollow profiles with weld seams were conducted using the magnesium alloy ME21 applying various extrusion ratios. Subsequent analysis of the profiles’ microstructure was performed comparing weld free with weld seam containing material using (polarized) light optical microscopy (LOM). Additionally, the local texture and microstructure in the weld-free material as well as in the weld seam region has been examined with a scanning electron microscope coupled with electron backscatter diffraction technique (SEM-EBSD). The weld-free material and the weld seam are characterized by recrystallized microstructures, whereas few residual cast grains were identified. The local texture distinctively changes from the weld-free material to the weld seam. The texture of the weld-free material is comparable with the typical ME21 sheet texture. In the weld seam area, a pole density is found, which is distributed towards the transverse direction (TD) combined with a split and broadening of the pole density in the extrusion direction (ED). This texture influences the mechanical anisotropy due to the dependence of the activation of basal 〈a〉-slip and \( \{ 10\bar{1}2\} \;\langle 10\bar{1}1\rangle \)-extension twinning on the loading direction in favorably oriented grains.

Distinct performance characters and inducing mechanisms of CO<SUB align="right">2 and N<SUB align="right">2 enhanced coalbed methane recovery

The distinction of performance characters and inducing multiple mechanisms in CO2 and N2 enhancement are ambiguous, even though the different stimulation performances have been discussed in existing studies. This article establishes an essential mathematical model and a comparison of the recovery dynamics with CO2 and N2 injection is conducted. The results indicate that the distinct characters of CO2 and N2 enhancement derive mainly from the different properties of porosity, permeability and gas sorption. The N2 injection appears more time efficient. The variation of porosity and permeability plays more complex roles when CO2 is injected as the coal seam is divided into two regions of gas concentration, pressure and cleat permeability. The influence of the coal seam and gas properties is discussed. The parameters related to the porosity and permeability variation and gas sorption inflict quite different influences between CO2 and N2 injection, while the coal seam intrinsic properties impact similarly. [Received: November 22, 2013; Accepted: September 7, 2014]

Influence of Surface Coatings of Filler Wires on Weld Seam Properties of Laser Beam Welded Copper Connections

In laser beam welding of copper its material properties require high intensities of the laser beam for a stable process, which are often realized by small focal diameters. Thus conventional laser beam welding of copper is accompanied by small bridgeable gap widths. A way to increase tolerable gap widths is the use of filler wires, which leads to higher energy consumption per unit length of the process, as extra energy is necessary to melt the filler wire. As some surface coatings are known to reduce energy consumption in laser beam welding of copper, this paper investigates the influence of surface coated filler wires on weld seam properties of laser beam welded of copper alloys with the aim of improved usage of the energy provided for the process. For this reason different coating materials and thicknesses of the filler wires are used within the experiments. The resulting weld seams are evaluated by means of geometrical, electrical and mechanical properties of the joints, e.g. seam width, cross-sectional area, electrical resistance, tensile strength and strain.

EXTENSION OF EXCAVATION DAMAGED ZONE DUE TO LONGWALL WORKING EFFECT

In advance longwall mining, the safety of mine network, production rate, and consequently, economic conditions of a mine are dependent on the stability conditions of gate roadways. The gate roadway stability is a function of two important factors: 1) characteristics of the excavation damaged zone (EDZ) above the gate roadway and 2) loading effect due to the caving zone (CZ) above the longwall working, which can extend the EDZ size. Generally, due to the coal seam dip, the failure possibility of main gate roadway is more severe than tail gate roadway. The aim of this work is to determine the longwall working effect on the EDZ extension above main gate roadway. To achieve this purpose, considering three factors involved in the CZ characteristics, the coal seam properties (dip and thickness) and the geomechanical properties of hangingwall, a new geometrical model is developed. Then, based on the geometrical calculations, a new relationship is presented to determine the working influence coeffiecint. Furthermore, taking into account the new geometrical model, an algorithm is suggested for the stability analysis of main gate roadways. Validation of the new geometrical model is carried out by the instrumentation and monitoring results of a longwall working carried out in the Parvade-2 coal mine of Tabas, Tabas, Iran. The results obtained show that there is a good agreement between the values obtained by the new model and the actual measured values. Finally, a sensitivity analysis is carried out on the effects of pillar width, bearing capacity of support system, and coal seam dip.

The Effect of Using Laser Engraving on Seam Properties of Weaving Denim Products

The Effect of Using Laser Engraving on Seam Properties of Weaving Denim Products

Influence of Adapted Wavelengths on Temperature Fields and Melt Pool Geometry in Laser Transmission Welding

Laser transmission welding is an established joining technology for the creation of strong, hermetic and aesthetic weld seams between thermoplastic parts. However, weld seam properties are strongly dependent on the optical properties of the materials involved. This paper investigates the wavelength-dependent absorption properties of polymeric materials and carbon black, their influence on temperature field generation and the resulting melt pool geometry in laser transmission welding. A FE simulation model is developed to examine the possibilities of influencing the temperature fields during contour and quasi-simultaneous laser transmission welding by adapting the wavelengths under consideration of the absorption and scattering properties. The application of laser wavelengths in the spectral range of 1400nm to 2000nm leads to modified temperature fields and melt pool geometries, which are expected to feature a better load-bearing capacity and a much improved gap-bridging capability.

The role of coal seam properties on coupled processes during CO2sequestration: A parametric study

AbstractIt has been proposed that a considerable amount of CO2can be safely sequestered from the atmosphere in geological formations such as coalbeds. In spite of promising evidence of the economic and technical viability of CO2sequestration in coal seams, many of its hydro‐geomechanical aspects are not fully understood. This paper presents a coupled hydro‐mechanical model that is used to assess the reservoir performance of a coalbed and the induced surface and subsurface deformations. A series of numerical simulations has been performed to study the effects of different parameters on the reservoir and geomechanical behaviors associated with CO2injection. A single‐phase dual‐porosity model is coupled to a one‐dimensional poroelastic model and an analytical model for the ground surface movements. Through these simulations, the role of three sets of parameters at different scales is investigated: fracture characteristics, matrix characteristics, and geomechanical/geometrical characteristics. The comparative impacts of these parameters on reservoir permeability, volume of the stored CO2, and deformations of the coalbed and the ground surface, are quantitatively assessed, in order to identify the most important parameters influencing the hydro‐mechanical response of the ground.

Prediction of cavity growth rate during underground coal gasification using multiple regression analysis

During underground coal gasification (UCG), whereby coal is converted to syngas in situ, a cavity is formed in the coal seam. The cavity growth rate (CGR) or the moving rate of the gasification face is affected by controllable (operation pressure, gasification time, geometry of UCG panel) and uncontrollable (coal seam properties) factors. The CGR is usually predicted by mathematical models and laboratory experiments, which are time consuming, cumbersome and expensive. In this paper, a new simple model for CGR is developed using non-linear regression analysis, based on data from 11 UCG field trials. The empirical model compares satisfactorily with Perkins model and can reliably predict CGR.

Influence of Surface Structured Filler Wires on Laser Beam Welding of Copper Alloys

Compared to steel, the required amount of energy for conventional welding of copper is higher, due to its higher thermal conductivity. This problem is mainly solved by preheating the work pieces or welding processes with high intensities such as laser beam welding. As the absorption of copper for infrared wavelengths, which are commonly used in industrial applications today, is typically low, the energy efficiency of the laser welding process is low. Besides this, if filler wires are used in order to increase the bridgeable width of joining gaps, the energy consumption of the process is further increased due to the additional amount of energy required to melt the filler material.As roughened surfaces of copper parts are known to increase absorption and consequently energy efficiency of laser beam welding without filler wires, this paper investigates the influence of surface structured filler wires on laser beam welding of copper alloys. Thus, the correlation between knurling geometries, absorption, molten volume and the welding result is investigated. For this reason, the welding result is evaluated by means of geometrical, electrical and mechanical weld seam properties e.g. seam width, weld reinforcement, area of cross-section, electrical resistance, tensile strength and strain.

The Influence of Knitted Fabrics’ Structure on Adequate Stitch Type and Density for Performance apparel

Performance apparel is playing a significant role in industry for special end use applications. One of the applications involves the formation of yarns to be made into performance fabrics through knitting or weaving. Performance CoolMax/Micro Modal, knitted fabrics, for purposes of this paper, are defined as fabrics used in specialty apparel, that are engineered for use in high-energy sports and activities performed in extreme environments. Clothing made of performance fabrics are said to be designed not only for fashion or just a passive cover for the skin, but to critically influence the comfort and performance of the wearer. Manufacturers have engineered these fabrics to manage moisture, regulate temperature, and provide protection from the surrounding environment. They are designed to interact with and modify the heat-regulating function of the skin as the surrounding environment interacts with them. In this study two different types of CoolMax/Micro Modal knitted fabrics (single jersey plated and interlock double face) with two various masses were produced for athletic sport suit. They were examined before and after sewing with two types of stitches (stitch type 512 and 601) and three different stitch densities. Tests were applied to determine the functional properties for performance depends on several factors like air permeability, water absorption and water absorbency to determine moisture management, abrasion resistance and crease recovery, which are quite important factors for knitted garments especially for sportswear. These properties may offer higher flexibility in designing such garments with optimized comfort properties. In addition to seam properties like seam thickness, seam stiffness, seam breaking force, seam pucker and seam appearance. All tests were carried out according to standards and took place into conditioned atmosphere of 21ºC and 65% RH. Comparisons have been made among them to determine the influence of knitted fabrics’ structure on adequate stitch type and density for performance apparel.

Inferring the Shape of Fractures and Hydraulic Properties of the Coal Seam Using Inverse Modeling on Pumping Test Results – Broke, NSW, Australia

Coal seam gas or coal bed methane production is becoming a significant industry in Australia. The area around the Broke township (located in the north-west of the Sydney Basin) has had coal seam gas exploration activities over the last decade. One methodology of well stimulation, hydraulic fracturing, has the potential to cause some environmental problems. The Broke region includes 4 aquifers (3 confined and semi-confined), more than 3 major coal seams (3 gas bearing) and has been covered by variety of different sedimentary rocks of Permian age. The groundwater system, with the gas bearing deposits is the function of conductivity and storativity (K and S) of the coal seam and geometry of properties of the fractures. The required data to investigate the hydraulic properties in the fractured zone includes; corehole data to assessment the geology and underground system, micro-seismic data to infer the fracture properties, pumping tests results, and monitoring wells data to evaluate the hydraulic properties of the coal seams. This paper investigates the shape of drawdown curves, resulting from the hydraulic pumping tests at Broke performed to determine the hydraulic and fracture properties, such as length, width, conductivity of fractures, and the proportion of the water and gas contained in the targeted coal seam. In order to reduce data uncertainty and increase the reliability of the hydraulic property estimation the Generalized Likelihood Uncertainty Estimation (GLUE) will be applied. Finally, with investigation of the shape (length and width) and conductivity of the fractures, the best monitoring method to ensure public safety of provide assurances that if problems occur the monitoring system will provide early warning for this study area will be determined.

Deep coal seams as a greener energy source: a review

Today, coal and oil are the main energy sources used in the world. However, these sources will last for only a few decades. Hence, the investigation of possible energy sources to meet this crisis has become a crucial task. Coal bed methane (CBM) is a potential energy source which can be used to fulfil the energy demand. Since the amount of carbon dioxide (CO2) emitted to the atmosphere from the use of CBM is comparatively very low compared to conventional energy sources, it is also a potential mitigation option for global warming.This paper reviews CBM recovery techniques with particular emphasis on CO2-enhanced coal bed methane (CO2-ECBM) recovery. The paper reviews (1) conventional CBM recovery techniques and problems associated with them, (2) CBM production-enhancement methods, including hydro-fracturing and enhanced CBM recovery techniques, such as N2-ECBM and CO2-ECBM, (3) the importance of the CO2-ECBM technique compared to other methods and problems with it, (4) the effect of CO2 injection during the CO2-ECBM process on coal seam permeability and strength and (5) current CO2-ECBM field projects and their progress.Although conventional CBM recovery methods are simple (basically related to the drawdown of the reservoir pressure to release methane from it), they are inefficient for the recovery of a commercially viable amount of methane from coal seams. Therefore, to enhance methane production, several methods are used, such as hydro-fracturing and ECBM (N2-ECBM and CO2-ECBM). The CO2-ECBM process has a number of advantages compared to other methane recovery techniques, as it contributes to the mitigation of the atmospheric CO2 level, is safer and more economical. However, as a result of CO2 injection into the coal seam during the CO2-ECBM process, coal mass permeability and strength may be crucially changed, due to the coal matrix swelling associated with CO2 adsorption into the coal matrix. Both injecting CO2 properties (gas type, CO2 phase and pressure) and coal seam properties (coal rank and temperature) affect this swelling. Although there are many related studies, a number of gaps exist, especially in the area of coal rank and how the effect of other factors varies with the rank of the coal seam. To date, there have been few CO2-ECBM field projects in the world. However, the reduction of CO2 injectability after some time of CO2 injection, due to coal matrix swelling near the well bore, is a common problem in the field. Therefore, various permeability-enhancing techniques, such as hydro-fracturing and injection of an inert gas such as N2 or a mixture of inert gases (N2 + CO2) into the seam to recover the swelled areas are under test in the field.

Studies on Influence of Stitch Density and Stitch Type on Seam Properties of Garment Leathers

Despite studies indicating the differential use of stitch density with respect to textile apparel, there is little information on the effect of stitch type and stitch density (stitches/cm or spc) on the seam properties of leather clothing. An experimental investigation of the effect of two different types of stitches (i.e., chain stitch and lock stitch with variations in stitch density of 3, 4, 5, and 6 spc) has been reported. Lock stiches performed better than chain stiches with regards to seam strength, seam elongation, and seam efficiency. A stitch density of 5 spc was found to be optimal for sewing leathers. Further increases in stitch density damaged the fabric by cutting and weakening the fabrics.

Analysis of Non-Uniform Distribution of the Equivalent Stress by Selected Multiaxial Fatigue Criteria in Butt-Welded Joint

Abstract Welded joints are areas of increased stresses in construction. The reason for this phenomenon is associated with the nonhomo-geneous mechanical, structural and geometrical properties of the weld seams. Generally, in the majority of the calculation it is assumed that the shape of the weld is uniform over the entire length and it is not deviating from the theoretical one. This article shows the distribution of stress in the butt-weld made of S355J2+N steel specimens. The shape of a joint was transferred to the finite element analysis by application of 3D scanning. Selected multiaxial fatigue criteria and probability mass function were used for a description of the results. Theoretical model prepared for comparison to the scanned joints was consistent with recommendations of International Institute of Welding for the effective notch method.

Assessment of Engineering Properties of Geosynthetics with Seaming Methods

8 Geotextiles (; 4 woven and 4 nonwoven types), 4 geogrids and 2 geocomposites of [nonwoven/fibers/nonwoven] structure were used as raw materials and the different seaming methods were applied to compare the seam properties of 3 geosynthetics and transmissivity of geocomposites. Tensile strength retentions of these geosynthetics were evaluated as the degree of damage by chemical degradation. Woven geotextiles showed the higher seam strength in the order (SSd-1 < SSd-2) > (SSa-1 < SSa-2) > geospacer without regard to the design strength. For nonwoven geotextiles, the order of seam strength is geospacer > (SSa-1 < SSa-2). Geogrids showed the higher seam strength in the order of band > geospacers but reduction factors were increased in the order of band > geospacer without regard to the geogrid’s compositions. Finally, geocomposites showed the higher seam strength in the order of geospacer > (SSa-1 < SSa-2) but showed the transmissivity in the order of geospacer > (SSa-1 > SSa-2) without regard to the kinds of filled fibers and weight of geocomposite.

English

The underground coal gasification (UCG) has a potential for converting the world’s coal resources into energy, liquid fuels and chemicals. The UCG process involves the injection of steam and air or oxygen into an underground coal seam and igniting and burning of coal in-situ to produce the combustible gas. Previous studies showed that many criteria affect site selection of UCG. The criteria include coal seam properties, faulting, discontinuity, properties of hanging wall and footwall of coal seam and hydrogeological regime. In this paper, considering proper UCG site selection criteria, coal seam was ranked and selected for the UCG based on the controlled retraction injection point (CRIP) configuration in Mazino coal deposit. The result of this investigation showed that the M2 coal seam has great advantage (considering the seam thickness and reservoir) related to the other coal seams for the gasification by CRIP configuration. Key words: Underground coal gasification (UCG), site selection criteria, Tabas coalfield, clean energy.

Dissolution kinetics of Si and Al from montmorillonite in carbonic acid solution

AbstractThe reaction between carbonic acid and montmorillonite minerals was studied in order to provide a theoretical basis for analyzing changes in the physical properties of coal seams after CO2 injection and for optimizing CO2 pumping parameters. A single montmorillonite mineral of purity >90 % was selected and subjected to reactions at 25, 35, and 45 °C in carbonic acid solutions of varying acidity. The Si and Al concentrations in the solutions and the structure and elemental compositions of the montmorillonite before and after the reactions were analyzed using a spectrophotometer, an X-ray diffractometer, and an energy-dispersive X-ray spectrometer; kinetic reaction models were established for the dissolution of Si and Al in carbonic acid solutions in order to estimate the apparent activation energy of Si dissolution under different acidity conditions. The results indicate that Al dissolved rapidly and soon reached solubility equilibrium. On the other hand, Si concentration in the solutions increased rapidly and then gradually declined with vibrations, with maximum values at 25, 35, and 45 °C, which were observed at approximately 96, 72, and 48 h, respectively. In addition, Si dissolution fitted the diffusion-controlled reaction model well; as the pH value decreased, the apparent activation energy of Si dissolution decreased, and Si became easier to dissolve. Furthermore, it was concluded that as a weak acid, carbonic acid causes little damage to the mineral structure of montmorillonite.