Bond Quality Research Articles

Process monitoring of ultrasonic metal welding of battery tabs using external sensor data

Ultrasonic metal welding (USMW) is a common used manufacturing technology for cell, module or pack assembly of Lithium-ion battery systems of pouch type. Since every single joint can affect the efficiency and safety of the entire battery system, quality fluctuations of the joint are one of the greatest challenges. Despite its industrial spread in battery manufacturing, USMW has a large number of influencing variables that may affect the bond quality but cannot be detected 100% failsafe with existing monitoring methods.Therefore the aim of this paper is to investigate the oscillation behavior of the tools and the joining members during USMW under different manufacturing conditions by monitoring external sensor data of structure-borne sound.In this paper typical manufacturing conditions in battery tab welding such as rolling direction and amplitude are set in order to study their effects on joint quality and the corresponding sensor signals. Therefore two laser vibrometers record the tool vibrations of the anvil and horn during the process. Occasionally, high-speed image capturing is also used to investigate the mechanism of process influences by studying the in-situ oscillation behavior of horn, anvil and the workpieces during USMW process. The sensor data analysis is correlated to thermal measurements and to the results of T-peel tensile testing and microstructural characterization of the bond interface to understand the effects of process influences during the welding process and its resulting joint quality.Based on the results, new insights for enhancing the process monitoring of USMW in Lithium-ion battery manufacturing are provided from identified sensor signals, that are correlating with the joint quality respectively different manufacturing conditions.

Stoneley waves with spring contact and evaluation of the quality of imperfect bonds

In this paper, the propagation of Stoneley waves along the interface between two orthotropic elastic half-spaces is investigated. The half-spaces are compressible or incompressible and they are in spring contact with each other. The main aim of the paper is to derive secular equations and formulas for the ratios of displacement components at the interface and to show that Stoneley waves are a good tool for evaluating the quality of imperfect bonds modeled as spring contacts. First, the secular equation and the formulas for the displacement-component ratios for the compressible case (two half-spaces are compressible) are derived. Then, those for the incompressible cases (one or both half-spaces are incompressible) are obtained by using the incompressible limit method. The obtained secular equations reveal that, while Stoneley waves are non-dispersive for the welded contact and the sliding contact, they are dispersive for the spring contact. Employing the obtained secular equations and formulas for the displacement-component ratios, two particular examples are carried out for determining the spring constants from the measured values of the displacement-component ratios and the wave velocity. It is shown that the ratios of displacement components at two sides of the interface are the best choice for evaluating the quality of imperfect bonds.

The mother-child attachment bond before and after birth: The role of maternal perception of traumatic childbirth

The quality of the mother-child attachment bond is a relevant factor for the psychosocial well-being of a child. However, some variables could affect this relationship, such as a perceived traumatic childbirth experience. The aim of this study was to explore the mediating role of the childbirth experience on the relationship between prenatal and postnatal attachment. A predictive study was conducted on 105 pregnant women aged 26 to 44 years. The data was collected at two different times: at week 31–32 of gestation (T1) and three months after childbirth (T2). The quality of maternal prenatal attachment has a significant and direct effect on postnatal mother-child attachment. Moreover, the quality of prenatal attachment represents a protective factor for the quality of childbirth experience, promoting a higher quality of postnatal attachment bond. Our results highlight the importance of supporting women throughout the perinatal period, starting from pregnancy to after childbirth.

A high-speed metal-to-polymer direct joining technique and underlying bonding mechanisms

Abstract A high-speed friction lap welding (FLW) technique for directly joining of aluminum to polymer is presented in this paper. Experimental results show that a consistent bond quality at the joint interface has been achieved at welding speeds as high as 5 m/min, which can be attributed to the formation of new C-O-Al bonds observed by X-ray photoelectron spectroscopy (XPS), in addition to mechanical interlocking. Lap-shear tests were performed for evaluating joint shear strengths of the welded samples corresponding to different welding conditions. It was found that as long as an interfacial threshold temperature was attained, the actual interface bond strengths are essentially the same regardless of welding temperature and welding speed.

Effect of Er:YAG Laser Etching on the Shear Bond Strength and Microleakage of Self-Glazed Zirconia Ceramics.

Objective: To investigate the effect of Er:YAG laser irradiation on the shear bond strength (SBS) and microleakage of self-glazed zirconia (SZ) ceramics. Background: SZ is a novel type ceramic; laser irradiation has started to be used in the surface treatment of different ceramics, while SZ has been rarely studied to improve the bond quality. Methods: One hundred twenty blocks (5 mm × 5 mm × 5 mm) of SZ ceramics were produced and split into eight groups following different surface treatments (n = 15): Group A: no treatment; Group B: standard grid processing; and Group C-H: different Er:YAG laser power settings (100, 200, 300, 400, 500, and 600 mJ). Ten blocks of each group received the measurement of SBS and fracture mode analysis, three blocks underwent the evaluation of the microleakage depths, and the other two blocks were observed under the scanning electronic microscopy (SEM). Results: Group F obtained the highest SBS and the lowest microleakage depth without damaging the ceramic surface structure, which was statistically significant compared with the control group and gridding group (p < 0.05), whereas the difference was not statistically significant (p > 0.05) between group E and group F. The results of bonding performance were consistent with failure types and observation of surface characterizations in SEM images. Conclusions: According to the results here, Er:YAG irradiation had effect on surface treatment. In addition, 400 mJ Er:YAG could increase the SBS and decrease the microleakage depth on SZ ceramics without damaging the surface structure.

Predicting the macroscopic response of electrospun membranes based on microstructure and single fibre properties

In the present paper, the three-dimensional structure and macroscopic mechanical response of electrospun poly(L-lactide) membranes is predicted based only on the geometry and elasto-plastic mechanical properties of single fibres supplemented by measurements of membrane weight and volume, and the resulting computational models are used to study the non-affine micro-kinematics of electrospun networks. To this end, statistical parameters describing the in-plane fibre morphology are extracted from scanning electron micrographs of the membranes, and computational network models are generated by matching the porosity of the real mats. The virtual networks are compared against computed tomography scans in terms of structure, and against uniaxial tension tests with respect to their macroscopic mechanical response. The obtained virtual network structure agrees well with the fibre disposition in real networks, and the rigorous prediction of the mechanical response of two membranes with mean diameters of 1.10μm and 0.70μm captures the experimental behaviour qualitatively. Favourable quantitative agreement, however, is obtained only after lowering the Young's moduli, yield stresses and hardening slopes determined in single fibre tests, and after reducing the density of inter-fibre bonds in the model of the membrane with thinner fibres. The simulations thus demonstrate the validity and merits of the approach to study the multi-scale mechanics of electrospun networks, but also point to potential discrepancies between the properties of electrospun fibres within a network and those produced for single fibre characterisation, and highlight the existing uncertainty on the density and quality of bonds between fibres in electrospun networks.

Effect of Electric Current-assisted Application of Adhesives on their Bond Strength and Quality.

To assess the effect of the application of different electric currents on dentin bonding and resin infiltration of self-etching and etch-and-rinse adhesives. Two hundred four sound third molars were selected and divided in groups according to the adhesive (self-etch [CSE, Clearfil SE Bond, Kuraray Noritake], universal [SBU, Single Bond Universal, 3M Oral Care], and etch-and-rinse [SB2, Adper Single Bond 2 (SB2), 3M Oral Care]) and electrical current used (0, 5, 10, 15, 20, 25, 30, and 35 μA). Light curing was performed for 10 s with an LED-curing unit at 1000 mW/cm2. Composite blocks were constructed of nanofilled composite in increments of 2 mm, which were light cured for 20 s. Specimens were sectioned into sticks with a cross-sectional area of ~1 mm2 and stored in distilled water at 37°C for 24 h. Microtensile bond strength (μTBS) testing (n = 8) was performed using a universal testing machine at a crosshead speed of 0.5 mm/min until failure. The bonding quality (n = 2) of adhesives applied with or without 35-μA electric current was evaluated using confocal laser scanning microscopy. Bond strengths were analyzed with two-way ANOVA and Tukey's test (α = 0.05). CSE presented the highest μTBS for all electrical currents tested. For CSE and SBU, electrical currents from 0-20 μA showed the lowest μTBS. Electrical currents from 0-10 and 20-25 μA yielded the lowest μTBS for SB2. CSE and SB2 applied under 35 μA showed a greater number of resin tags in dentin tubules. Fluorescein penetration into the hybrid layer was found for SBU applied without electric current. The application of adhesives using 35-μA electric current improved the bond strength and quality of the adhesive interface.

Media-Tight Polymer-Polymer Assemblies By Means of Sintered Powder Layer in Assembly Injection Moulding

The demand for media-tight assemblies has increased continuously in recent years. The explanation for this is the increasing automation, which not only is the reason for more electronics and sensors, but also for the application in increasingly exposed areas. Components must be efficiently protected from these new stresses, such as those caused by contact with aggressive and corrosive media. Assembly injection moulding is a process suitable for large series production that can be used to achieve a protective effect by overmoulding. The focus in this article is a novel and innovative approach that exploits local additive structuring to generate increased media-tightness due to a labyrinth sealing effect. Using an IR spot, the surface of the insert made of polyamide 12 (PA12) is melted and a powder layer made of PA12 is applied, thus creating a structure made of identical material. The inserts prepared in this way are overmolded with polypropylene (PP). The properties of this adhesion-incompatible polymer combination were then examined with regard to their bond quality in the pull-out test and their media-tightness by differential pressure method. It was shown that the additive structuring clearly increased both the bond quality and the media-tightness. This showed the functionality of the pre-treatment. In addition to the feasibility, various application variants were investigated in order to be able to define an initial process window. Overall, it was shown that, depending on the powder application, very good local tightness increases can be achieved.

Low Formaldehyde Emitting Urea Formaldehyde Resin for Plywood

Urea formaldehyde resins were prepared in the laboratory using keratin through copolymerization reaction. Conventional Urea formaldehyde resins were also manufactured without the addition of keratin during the reaction. Through the determination of such reaction technology as molar ratio, adding a sequence of keratin and adding amount of keratin, we synthesized the low toxic urea resin. The resins were admixed with suitable hardener and the panels were made. Bond quality and formaldehyde content were evaluated. The results show that adding amount of 5 % keratin and adding keratin with the third feeding of urea is the best choice. From the studies, it was found that keratin addition reduces the formaldehyde content in the panel without affecting the strength properties

Manufacture of Tungsten Heavy Alloy Tube by Diffusion Bonding of Semicircular Tubes

An innovative manufacturing method to fabricate tubular parts made of tungsten heavy alloy (THA) by diffusion bonding of sintered semicircular tubes is proposed and characterized in this study. THAs are produced by blending tungsten grains with a lower-melting-point Ni-Fe binder metal. During the liquid phase sintering (LPS) process of THA, the Ni-Fe liquid wets the tungsten and provides a soluble diffusion network for rapid sintering. Multi-phase THAs are usually very difficult to produce as a tubular piece. During the LPS of the powder compact, a gravity-induced slumping leads to some distortion in the bottom of the tubular parts. One possible alternative to handle this problem is to combine the segmented THA pieces by solid-state diffusion bonding to build up tubular piece. Thus, this study proposes combining the semicircular THA tubes using the diffusion bonding technique to manufacture the tubular THA parts. To provide uniform contact pressures along the joining surfaces, horizontal diffusion bonding is performed using a specially constructed supporting apparatus to reduce the gravity effect. An industry-applicable tube manufacturing process has been well characterized, and its feasibility has been demonstrated by bond quality that was assessed by optical metallography and mechanical testing.

Environmental awareness and development of the financial market

The relevance of the paper is caused by the need to find new channels to attract public funds to the domestic stock market. It is known that the population of Russia invests in securities no more than 5% of their savings. The study of the pro-environmental behavior of investors in the Russian stock market seems to be very relevant and useful in line with the policy of the Bank of Russia in the financial market. In the “Guidelines for the Development of the Russian Financial Market in 2019 – 2021”, it was noted that the rapid development of financial technologies, changing consumer demands, the growing cross-border nature of financial services, new approaches to regulation in the world create additional opportunities for the development of the domestic stock market [1]. The subject of the study is the pro-environmental awareness of investors in the stock market, which results in the formation of a new investment quality of green bonds. The aim of the study is to identify the factors and conditions of pro-environmental behavior of investors in the Russian stock market, ensuring the development of green financing mechanisms. Methodology. To study the pro-environmental behavior of investors in the Russian stock market, the main factors that influence the pro-environmental behavior of investors in the Russian stock market and the practice of disclosing non-financial statements by issuers of green bonds in the stock market are systematized. In substantiating the findings, comparative, economic and statistical methods of analysis were used.

Effect of Crosslinked Chitosan Nanoparticles on the Bonding Quality of Fiber Posts in Root Canals.

To investigate the effects of root-canal dentin pretreatment with the crosslinker EDC combined with chitosan nanoparticles (Csnp) on the bonding quality of fiber posts in root canals in terms of bond strength, nanoleakage, quantification of collagen degradation, and degree of conversion (DC) of adhesive. Forty-eight single-rooted teeth were prepared endodontically and etched using UNI-ETCH (Bisco) as per the adhesive procedure for fiber posts. They were randomly divided into three groups before adhesive (All-Bond 3) application, according to different pretreatments: a. immersed in 2.5% glutaraldehyde for 24 h; b. treated with Csnp solution under ultrasonic agitation for 60 s and immersed in EDC crosslinker for 24 h; c. without treatment (control). Bond strength, nanoleakage, DC within the interface, and collagen fiber degradation were evaluated. The pretreatments had a significant influence on the bonding stability of fiber posts in root canals, but not on the degree of conversion (p = 0.552). Enzymatic degradation significantly influenced bond strength for all groups (p = 0.001), with the greatest effect found in group c. The amount of amino acids released from the adhesive interface differed significantly between groups after hydrolysis and enzymatic degradation (p = 0.000); group c released the highest amount of amino acids. Csnp binding to dentin in combination with EDC reduced degradation of dentinal collagen and improved the stability of the adhesive interface without jeopardizing adhesive polymerization.

Static bending of glulam beams manufactured with rubber wood and epoxy adhesive

The aim of this study was to evaluate the properties of Hevea brasiliensis wood wastes for production structural pieces of glued laminated (glulam) timber. Three trees with age close to 25 years and diameter at breast height (DBH) higher than 500 mm were obtained. The basic density of the wood were quantified, as well as the stiffness and the strength in static bending, shear strength and parallel compression to grain and hygroscopic equilibrium moisture. The beams of glulam were evaluated according to the modulus of elasticity (MOE), modulus of rupture (MOR) and delamination. Due to the bending properties MOR (75.14 MPa) and MOE (8166.79 MPa), as well as the shear strength (12.29 MPa) obtained, was concluded by the suitability of the rubber wood for the production of glulam beams. The composite beams presented values of MOR (75.14 MPa) and MOE (8166.79 MPa) compatible with species traditionally used in the production of glulam beams. The adhesive bond quality was verified by the delamination test, presenting delamination of 4.95 %, indicating its use for internal and external environments. Keywords: Composite; Wood; Bond resistance; Static bending.

Power Ultrasonic Additive Manufacturing: Process Parameters, Microstructure, and Mechanical Properties

Additive manufacturing (AM) for fabricating 3D metallic parts has recently received considerable attention. Among the emerging AM technologies is ultrasonic additive manufacturing (UAM) or ultrasonic consolidation (UC), which uses ultrasonic vibrations to bond similar or dissimilar materials to produce 3D builds. This technology has several competitive advantages over other AM technologies, which includes fabrication of dissimilar materials and complex shapes, higher deposition rate, and fabrication at lower temperatures, which results in no material transformation during processing. Although UAM process optimization and microstructure have been reported in the literature, there is still lack of standardized and satisfactory understanding of the mechanical properties of UAM builds. This could be attributed to structural defects associated with UAM processing. This article discusses the effects of UAM process parameters on the resulting microstructure and mechanical properties. Special attention is given to hardness, shear strength, tensile strength, fatigue, and creep measurements. Also, pull‐out, push‐out, and push‐pin tests commonly employed to characterize bond quality and strength have been reviewed. Finally, current challenges and drawbacks of the process and potential applications have been addressed.

Detecting first layer bond quality during FDM 3D printing using a discrete wavelet energy approach

Fused Deposition Modeling (FDM) is a highly versatile additive manufacturing method for 3D printing thermoplastic-based components at small as well as larger production scales. By combining the filament with fibers from other materials including wood, metal, glass, and carbon, the method can easily be adapted to print complex parts using a variety of materials. However, despite its popularity, online print quality and machine monitoring continue to remain a challenge. Here, we present the preliminary results from our efforts on using cheap off-the-shelf sensors in combination with discrete wavelet transform analysis to identify the differences in the vibroacoustic signals measured near the print area during successful and failed first layer filament deposition on the build plate. A failure in creating a strong first layer bond between the extruded filament and the build plate always results in a print failure and is one of most common print issues occurring in FDM printing. By controlling the extruder and build plate temperatures, we control the filament – build plate bond strength while measuring the generated vibroacoustic signals using a PVDF piezo sensor. The measured signals are analyzed using a discrete wavelet transform to partition the signal energy into different energy levels. For the cases studied, we find that the relevant noticeable differences can be observed in specific energy levels during good and bad bond formation. Reconstructing the signal using these energy contributions provides a time domain representation of signal differences under different conditions. The obtained results demonstrate that a cheap and easy to implement method can be developed using PVDF sensors in combination with a wavelet-based signal analysis approach.

Development of an aluminum compound casting process - Experiments and numerical simulations

The casting of liquid melt on a preheated substrate layer to produce a metallurgical compound represents a direct approach towards clad aluminum strips. To investigate this direct process route and the formation of a metallurgical bond at the interface, a small-scale pilot plant to cast pure aluminum on strips of aluminum alloy 7075 under controlled conditions was developed. Composite casting plates were produced at varying casting parameters (preheating temperature of the substrate, clad layer thickness, casting speed, melt temperature) and subsequently analyzed by metallographic means to classify the bond quality. Suitable thermal conditions for the melt flow in the casting device were found by numerical simulation using a commercial fluid flow and solidification software package. Additional meso- and micro-modeling of the casting and the bonding zone supported the understanding of the bonding mechanism. The heat transfer in the macro-model of the casting device was calibrated using measured temperatures obtained during compound casting experiments. A finer meshed two-dimensional meso-model of the casting device was derived from the macro-model to gain more accurate information about the temperature distribution in the vicinity of the bonding zone. This interface between the pure aluminum and the aluminum alloy was modeled in extremely high temporal and spatial resolution (micro-model) as temperatures are not accessible there by direct measurements. These simulation results show the time-resolved re-melting and re-solidification of the aluminum alloy during compound formation. The obtained simulation results correlate very well with electrochemically etched cross sections of cast bilayer aluminum strips. The experiments show that the oxide layer at the interface has to be removed completely during the casting process to obtain high quality compounds. The assumed mechanism of detachment and transport of the fractured oxide is shown schematically and necessary thermo-mechanical conditions for the removal of the oxide skin are discussed.

Investigation of the Influence of Bonding and Thermal Ageing Duration on the Peeling Strength of Knitted Materials’ Bonds

Bonding technology namely as “sew free” technology is usually applied for joining the pieces of sportswear and leisure clothing. Influence of the thermal ageing duration on the peeling strength of woven fabric and knitted materials bonded at 150°C temperature for 10 s, 20 s, 30 s, and 40 s durations with two polyurethane films of 0.175 mm and 0.127 mm thicknesses has been investigated in this research. Based on the research results it was shown that the peeling strength of the textile bonds is dependent on material type and bonding duration, but it is not highly affected by the ageing at 45°C temperature for 150 min, 300 min, and 450 min. During concluding it may be stated that ageing at 45°C temperatures is not main factor influencing the bond quality during its exploitation in high temperature environment.

The Effect of the Cyclic Steam Stimulation on the Thermal Cement Bond: Cased Hole Wire Logging Evaluation (Segmented versus Original) Tools

When focusing on the oil thermal well life integrity, One of the current trends is to optimize the use of the innovative solutions in order to improve the quality of the cement bonding (i.e. cement to pipe bond and formation). This trend is in a trail application in Fula North East thermal wells in Sudanese oilfields. The objective of this paper is to discuss how the Cyclic Steam Stimulation (CSS) in huff and buff manner directly affecting the cement bond by using wire ling logging tools which usually run to determine cement to casing and formation relationships as well as to evaluate cement conditions such as channeling, compromised cement (i.e. gas cut, dehydrated, etc.), cement stages, cement top and micro annulus [1] . In this analysis, the cement evaluation logs comparison between the two classes of sonic logging tools which are sonic CBL/VDL and SBT/VDL had been used to evaluate thermal cement bond before and post the CSS in FNE-X0 and FNE-X1 well candidates. The results show that thermal cement bond has seriously affected by applying the CSS based on the cement bond logs interpretations and analysis, the SBT/VDL has shown that the bond quality of the cement bond was affected in a critical manner after the first cycle of steam injection. The Segmented Bond Tool (SBT) is a new cement integrity tool which has been developed to affords a complete cement bond analysis in one logging pass and the channel as small as 15 degrees can be detected as well as many of the problems common to the standard mandrel-type tools are effectively eliminated

Influence of Upset Pressure on Microstructure and Mechanical Properties of Friction-Welded AISI 4140 Low Alloy Steel Pipes

In the present study, low alloy steel AISI 4140 pipe in reheated, quenched and tempered (RQT) condition was friction-welded using 6.4 MPa upset pressure followed by post-weld heat treatment as per the manufacturing practice prevailing in the drill pipe industry and compared the same with friction welds made at different upset pressures in the RQT condition and in the as-received condition to evaluate bond quality. The weld region consisted of a mixture of tempered martensite and ferrite in case of RQT condition and mixture of lath martensite/upper bainite and ferrite in the as-received condition. As the upset pressure was increased, the martensite lath size decreased in both as-received and RQT conditions. In general, as the upset pressure was increased, the average microhardness increased. The average microhardness of the material adjacent to partially deformed zone showed lower hardness due to tempering effect because of weld heat. The upset pressure 6.4 MPa showed better notch tensile strength ratio confirming better ductility of the weld zone. The impact strength decreased as the upset pressure increased in both as-received and RQT conditions. But as-received condition showed significantly lower impact strength due to higher carbide content at the weld interface.

Short Form Version of the Father and Mother Attachment Questionnaire (FMAQ)

The Father and Mother Attachment Questionnaire (FMAQ) is a 30-item self-report measure developed for assessing adolescents’ and young adults’ representations of attachment relationships with each parental figure separately, across three dimensions: quality of emotional bond, separation anxiety, and inhibition of exploration and individuality. Five studies were conducted to develop a short-form of FMAQ and to examine whether this new short measure presented with fit psychometric properties. Study 1 involved Item Response Theory (IRT) analyses with 563 Portuguese adolescents and aim to select the best items to include in the short-form of the FMAQ. Studies 2 to 5 aimed to replicate the reliability and factor structure found in Study 1 through confirmatory factor analysis on independent samples of adolescents, young adults and adults. The IRT results suggested including 15-items in the short-form of FMAQ. The results provide support for the adjustment of the short factor structure, internal consistency, and invariance measurement (among gender of participants and parental roles), and predictive validity across different samples. The results obtained in the five studies indicate that the short-form FMAQ is a reliable instrument to assess the quality of attachment to parents in adolescence and emerging adulthood, as well as to evaluate adults’ perceptions of their parents as attachment figures during their adolescence. Thus, we suggest this short-form as a promising research tool for researchers quickly to assess attachment to parents in these ages taking into account a three-dimensional approach.