Bond Quality Research Articles

Nondestructive Evaluation of FRP‐Concrete Interface Bond due to Surface Defects

Carbon fiber‐reinforced polymer (CFRP) laminates have been successfully used as externally bonded reinforcements for retrofitting, strengthening, and confinement of concrete structures. The adequacy of the CFRP‐concrete bonding largely depends on the bond quality and integrity. The bond quality may be compromised during the CFRP installation process due to various factors. In this study, the effect of four such construction‐related factors was assessed through nondestructive evaluation (NDE) methods, and quantification of the levels of CFRP debonding was achieved. The factors were surface cleanliness, surface wetness, upward vs. downward application, and surface voids. A common unidirectional CFRP was applied to small‐scale concrete samples with factorial combinations. Ground‐penetrating radar and thermography NDE methods were applied to detect possible disbonds at CFRP‐concrete interfaces. Thermography was found to clearly detect all four factors, while the GPR was only effective for detecting the surface voids only. The thermal images overpredicted the amount of debonded CFRP areas by about 25%, possibly due to scaling errors between the thermograph and the sample surface. The maximum debonded CFRP area in any sample was about two percent of the total CFRP area. This is a negligible amount of debonding, showing that the factors considered are unlikely to significantly affect the laminate performance or any CFRP contribution to the concrete member strength or confinement.

Jak zwiększyć przyczepność stal zbrojeniowa-beton?

The paper analyses the impact of casting direction of self-compacting concrete (SCC) on its bond quality to steel reinforcing bars. Tests were performed on high performance self-compacting concretes with different amount of silica fume to cement mass. Experiment was carried out on 480 mm height specimens, which allowed determining changes of bond condition along its height. The ribbed reinforcing bars have been placed perpendicularly to the direction of casting. Casting was performed from two points – from the bottom and the top of the form. Research has shown that casting from the bottom of the form improves bond strength and quality.

Strength and rigidity of the masonry fragment in a fuzzy setting

The strength and stiffness of masonry depend on various factors, such as the properties of the brick and mortar, their specific volume, relative position and quality of adhesive bonds. A high degree of uncertainty of these factors and a large scatter of experimental data in the testing of bricks and mortar are the important features of the masonry. In this paper, we present a mathematical model that allows us to determine the averaged characteristics of masonry based on the mechanical properties of substructural materials and their specific volume content in a fuzzy setting. All input parameters allowing to obtain fuzzy estimates of stresses and deformations of a brickwork fragment are determined by membership functions. For a representative volume of masonry, dependencies are obtained that allow to determine the level of destructive loads and the nature of destruction.

Effectiveness of Infant Massage on Strengthening Bonding and Improving Sleep Quality

Background : Baby massage is the oldest and most popular touch therapy known to mankind, which is also the art of health care and treatment that has been practiced for centuries. This study aims to determine the effect of infant massage on bonding attachments between mother and baby and the quality of infant sleep. Subjects an d Met h od: This was experimental study with Randomized Controlled Trial (RCT) design conducted in five health centers in Ponorogo Regency, East Java in March to April 2019. The total sample was 120 mothers and infants aged 3 to 6 months divided between massage groups (treatment) and not massage (control) based on The dependent variable of this study was bonding attachment and sleep quality. The independent variable in this study was infant massage. Data collection was using questionnaires and checklists. This study used the Mann-Whitney test Result : Infant massage effectively increased bonding attachment (effect size = 6.19; p <0.001), increased infant sleep duration (effect size= 2.79, p <0.001), decreases the number of baby awakened (effect size = -2.78; p <0.001), decreased duration awakened (effect size= -0.80; p= 0.001), Conclusion : Baby massage effectively increased bonding attachment and sleep duration, and effectively decreased the number of awakenings and the duration of awakening. K eywords : baby massage, bonding attachment, sleep quality Co r responden ce : Ainurrizma Tri Hartanti, Public Health Postgraduate Program, Universitas Sebelas Maret. Jl. Ir. Sutami 36 A, Surakarta 57126, Central Java. Email: ainurrizma.th@yahoo.co.id . Mobile: 085784939555 Indonesian Journal of Medicine (2019), 4(2): 165-175 https://doi.org/10.26911/theijmed.2019.04.02.10

The Effect of Different Mixing Methods on the Properties of Calcium-enriched Mixture Cement: A Systematic Review of in Vitro Studies.

It has been shown that the mechanical and physical properties of Calcium Enriched Mixture (CEM) cement are influenced by the mixing methods. Despite several studies conducted on different mixing methods of CEM cement, there is no systematic review to summarize the results. This systematic review was conducted to investigate the effect of different mixing techniques on mechanical and physical characteristics of CEM cement. A professional librarian with skills in informatics conducted a systematic search by searching electronic databases PubMed/MEDLINE, Scopus and Ovid for English language peer-reviewed articles published between 1992 and April 2019. Initial searches from all sources identified 1175 references. Two of the authors examined the titles, abstracts of these articles and the full reports of 20 studies were obtained, and data extraction was performed. Seven studies satisfied the eligibility criteria for the review. The effect of different mixing methods was investigated on bacterial microleakage, push-out bond strength, flow rate, compressive strength, solubility, pH, film thickness, dimensional changes, working time, setting time and quality of the apical plug. Based on the results of this systematic review, some of the important properties of CEM cement were affected by different mixing methods. Although none of these mixing methods could improve all the properties, mechanical and manual methods were more effective compared to ultrasonic method.

Collective Cu-Cu Thermocompression Bonding Using Pillars

Abstract The demand for high-performance, high-functionality packages for integrated circuits continues to grow. Three-dimensional (3D) integration is strongly being pursued to meet this demand and has started to reach maturity and industrial adoption. As advanced 3D system designs progress, requiring higher 3D interconnect density with pitches of 10 μm and lower, traditional chip attachment through solder bump technology will likely face complex manufacturing and reliability challenges. Cu-Cu thermocompression bonding has been proposed as a key 3D-enabling technology and alternative to solder. One of the main issues challenging its commercialization in high-volume manufacturing is the sensitivity of Cu-Cu bond quality to prebond surface conditions. This is especially true for die bonding applications which have limited rework options once chips have been singulated. This article outlines further development and demonstration of a tack and collective bonding scheme for Cu-Cu thermocompression bonding. This approach mitigates many of the thermal and throughput issues of a chip-level Cu-Cu attachment process by performing the quick chip alignment at a low temperature and then subsequently completing all Cu bonding simultaneously. The specific use of an intermediate handle wafer between the tack and collective bonding steps allows chips to be reconstructed into a wafer form that facilitates the cleaning and surface preparation of the chips before bonding using standard wafer processing equipment. A chip-to-wafer test structure designed for Cu pillar-to-pad bonding was used as part of this demonstration and illustrates the feasibility of the application. Full transfer of chips to a receiving device wafer using the tack and collective bonding process is shown with electrical test results and selected bond-integrity metrology confirming substantial bond yield and strength.

Effect of Surface Micromorphology on the Deformation and Bonding Quality of Stainless Steel/Carbon Steel during Hot Isostatic Pressing

Effect of Surface Micromorphology on the Deformation and Bonding Quality of Stainless Steel/Carbon Steel during Hot Isostatic Pressing

Bond Quality Inspection of Bonded Surfaces using Microwave NDE

Bond Quality Inspection of Bonded Surfaces using Microwave NDE

Pengaruh DER, CAR, dan ROE terhadap Peringkat Obligasi Perbankan yang Listing di PT Bursa Efek Indonesia pada Periode 2008-2013

This study aims to analyze the effect of Debt to Equity Ratio (DER), Capital Adequacy Ratio (CAR) and Return on Equity (ROE) both partially and simultaneously to bank bond ratings. Bond rating agencies are needed to assess the performance of banks that issue bonds by providing information about the quality and risk of bonds. The phenomenon in Indonesia occurs when several issuers fail to pay but have a bond rating at the investment grade level. The risk of a default on bonds is seen in the case of a failure to pay PT Bank Global Tbk bonds where the Kasnic rating agent gave an A- rating, but when BI announced a freeze on Bank Global's license, the bond rating was reduced to D. This research used Ordered Logit Model (OLM) as a method of data analysis.The random sampling method was carried out as a sampling method. The results of this study showed two things. First, the Capital Adequacy Ratio (CAR) and Return on Equity (ROE) had a positive impact on the bond rating. Second, the Debt to Equity Ratio (DER) had a negative impact on the bond rating. Whilst simultaneously Debt to Equity Ratio (DER), Capital Adequacy Ratio (CAR), and Return on Equity (ROE) affected the bond rating.

A influência do board interlocks na prática da divulgação voluntária em empresas brasileiras

O estudo investiga a influência da estrutura de formação do board interlocks na divulgação voluntária de empresas de capital aberto no Brasil. Utiliza-se a abordagem de análise de redes sociais para captar e avaliar o nível de relacionamento existente entre empresas em função dos laços formados por membros do conselho de administração. Duas hipóteses exploram as medidas de (i) centralidade de grau (degree centrality) e de (ii) centralidade de intermediação (betweenness centrality), as quais têm potencial de descrever o posicionamento dos atores em uma rede. A terceira hipótese endereça a questão da qualidade dos laços (holes). Os resultados sugerem que a estrutura de formação do board interlocks aumenta a propensão de as empresas reportarem informações de natureza voluntária em seus relatórios anuais. Interpreta-se, por isso, que o board interlocks atua como um fator que favorece a disseminação de práticas de divulgação voluntária.

Benefits, challenges, and needs of people living with cancer and their companion dogs: An exploratory study

Purpose/Objectives: The study examined whether the bond with a companion dog is associated with well-being among people with cancer, and described the perceived benefits, challenges, and needs accompanying the relationship with the dog.Design: The design was cross-sectional.Sample: Participants were 140 people recently diagnosed with cancer with at least one dog in their household.Methods: The online survey included measures of the human–pet bond, depressive symptoms, positive affect, and health-related quality of life, as well as open-ended questions about the experience of having a dog since being diagnosed with cancer.Findings: Although the bond with a companion dog was not directly linked with well-being, the association between the human–pet bond and depressive symptoms depended in part on treatment status.Conclusions: Companion dogs may play an important role in the lives of people recently diagnosed with cancer.Implications for psychosocial providers: Health care providers can help to support the bond with a companion dog.

Bond strength evaluation of heat treated Cu-Al wire bonding

Bond strength evaluation of wire bonding in microchips is the key study in any wire bonding mechanism. The quality of the wire bond interconnection relates very closely to the reliability of the microchip during performance of its function in any application. In many reports, concerns regarding the reliability of the microchip are raised due to formation of void at the wire-bond pad bonding interface, predominantly after high temperature storage (HTS) annealing conditions. In this report, the quality of wire bonds prepared at different conditions, specifically annealed at different HTS durations are determined by measurements of the strength of the interface between the bond wire and the bond pad. The samples are tested in pull test and bond shear test. It was observed that the higher bonding temperature as well as the longer duration of HTS increased the bond strength. This is represented through the analysis of the measurements of ball shear strength. This is due to the fact that higher bonding temperature and longer HTS promoted better growth of the Cu-Al IMC layer. A transmission electron microscopy - energy dispersive X-ray analysis (TEM-EDX) has been carried out to observe the formation of the Cu-Al IMC layer in the sample.

Low-Temperature Cu-Cu Bonding Process Based on the Sn-Cu Multilayer and Self-Propagating Reaction Joining

Transient liquid phase bonding can be realized at a relatively low temperature through building an intermetallic interconnection. A self-propagating reaction joint can achieve a low temperature bond by confining the heat at the bonding interface and reduce the thermal effect on other components. In this work, a Sn-Cu alternating multilayer was combined with an Al-Ni self-propagating reaction joint to develop a highly efficient low-temperature Cu-Cu hybrid bonding process. The Sn-Cu alternating multilayer was directly prepared on the Cu substrates by an alternating electroplating process. The Al-Ni multilayer film was sandwiched between two Cu substrates under a pressure of 5 MPa and ignited with a 15-V spark at room temperature. Cu-Cu bonds with three different Sn/Cu thickness ratios were studied. It was found that the Cu6Sn5 layer within the three Sn layers had different thicknesses and decreased with increasing distance from the heat source of the Al-Ni nanofoil. The thickness difference between adjacent Cu6Sn5 layers at first decreased with the increasing Sn/Cu thickness ratio in these three groups and then remained constant. The shear strength of the bonds varied with the thickness of Cu6Sn5 layer and achieved a high shear strength with a Sn/Cu thickness ratio of 1.6 μm/1 μm, where fracture occurred within the Cu6Sn5 layer near the Cu substrate. The combination of the Sn-Cu multilayer and self-propagating reaction joining process can achieve a good low-temperature bond between Cu substrates with an optimized Sn/Cu thickness ratio, which has a strong influence on the quality of bonds, the Cu6Sn5 morphology, and shear strength.

Calculation of the load-bearing capacity of the brickwork fragment with uncertainty high degree in the materials properties

The mechanical properties of brickwork depend on a multitude of different factors such as components properties, their specific volume content, relative location and the quality of adhesion bonds. An important feature of the masonry is the high degree of these factors indeterminacy and the wide scatter of the experimental data in the testing of bricks and mortar. We present a mathematical model that allows determining the mechanical characteristics of the masonry based on the mechanical properties of the brick and mortar, their specific volume content in a fuzzy setting in this paper. All input parameters, which allow to obtain interval estimates of stresses and deformations of the brickwork fragment, are determined by membership functions. The simulation results are compared with the experimental data of other authors.

Isocyanate-terminated urethane-based dental adhesive bridges dentinal matrix collagen with adhesive resin

Commercially available dental adhesives fail to chemically unite the demineralized collagen matrix with resinous materials within the resin-dentin interface. Sub-micron separations between the collagen fibrils and polymerized resin provide the backdrop for bond deterioration. Here, novel isocyanate-terminated urethane methacrylate precursors (UMP) were synthesized with the capacity to bond chemically to dentin collagen via covalent and hydrogen bonds. Collagen grafted with UMP also copolymerized with other methacrylate resin monomers, thereby producing a monoblock of chemically-linked biocomposite. The viscosity, degree of conversion and biocompatibility of UMP are comparable with commercially available resin monomers. An experimental adhesive containing 40% UMP demonstrated co-polymerization capability, good infiltration capacity and achieved higher immediate bond strength to dentin than the control commercially available adhesive. Improvement of dentin bonding by incorporation of UMP into dentin adhesives justifies future evaluation of the potential of these UMP-based adhesives in extending the longevity of resin-dentin bonds. Statement of SignificanceComposite-adhesive restorations have become an indispensable treatment modality in contemporary restorative dentistry. While the inability of these adhesives to bond chemically with collagen undermines the bond quality. This study describes a novel isocyanate-terminated urethane multi methacrylate precursors (UMP) which can bridge dentinal matrix collagen with adhesive resin by covalent and hydrogen bonds. Furthermore, an experimental UMP-based adhesive shows better co-polymerization capability, good infiltration capacity and higher immediate bond strength than the putatively effective adhesive Single Bond 2. The new chemical bonding mechanism based on UMP would theoretically produce more stable bonding interface that are more resistant to degradation.

Development of the symmetrical laser shock test for weak bond inspection

This study aims to assess the capability of the LAser Shock Adhesion Test to detect weak bonds in assemblies made of carbon fibre reinforced polymer laminates as well as understand the behaviour of different bonded composite structure under a shock load. A specific setup based on symmetrical laser shocks has been used. After each test, ultrasounds are used to determine if the bond has been damaged or not. At first, samples with two contaminants - de-icing fluid and finger prints - were studied. Then, the bond quality of two partially contaminated aircraft parts were investigated. These original results demonstrate the efficiency of the symmetrical laser shocks method as a Non-Destructive Test for bonded carbon fibre reinforced polymer assemblies.

Horizontal and Complex-Trajectory Wells (November 2018)

Technology Focus With the arrival and development of rotary steerable systems (RSSs) in the late 1990s, the industry thought that drilling a perfectly smooth and controlled trajectory would not be an issue anymore. Two decades later, we’re still talking about wellbore quality, especially when drilling these long and complex horizontal wells where wellbore quality is even more important. Whatever definition is accepted for wellbore quality and associated tortuosity, we all know that drilling a perfectly smooth and gauged borehole is key for many aspects—for example, weight-on-bit transfer, vibrations, equipment fatigue and failure, torque and drag, buckling, quality of cement bond, completion or casing running, quality of logging, artificial lift, wellbore placement, and production. If the industry wants to drill 15,000-ft-and-greater lateral sections in the unconventional market, more attention should be focused on measuring and achieving wellbore quality. If it is well-accepted now that measuring inclination and azimuth every 100 ft or so is not enough, most of the time the actual hole size drilled is not known precisely because no caliper tool is generally run in the wellbore. This is a sector of the industry in which progress would be very valuable for drilling and completion optimization. One of the papers selected this month also illustrates that RSSs do not necessarily drill very smooth wellbores because tortuosity is inherent to the drilling process regardless of the directional system. Measuring wellbore quality accurately has enabled RSS manufacturers to improve the steering mechanism of these tools significantly to reduce the level of tortuosity and drill smoother wellbores. Directional-drilling companies and drilling contractors also have seen the benefit of better control of the conventional steerable assembly by using more automation at the surface to steer the wellbore more consistently and eventually drill a smoother borehole. Drilling of longer laterals has led to a surge in the use of various downhole tools to remove friction and ledges/rugosities, which has highlighted evidence of sometimes poor wellbore quality. Diverse oscillation tools are used almost systematically along the string to decrease drag by shaking the string, and reamers equipped with cutters are used along the bottomhole assembly to remove ledges and clean the wall of the wellbore. Regardless of which technology is used, remember that good drilling practices and good knowledge of the rock to be drilled (and its interaction with the drilling fluid for better wellbore stability) contribute significantly to better wellbore quality. Obviously, drilling a perfect and smooth wellbore might cost a little more by using this technology and optimization, but long-term savings should be guaranteed. Recommended additional reading at OnePetro: www.onepetro.org. IADC/SPE 189612 Anticollision Best Practices Developed for Horizontal Drilling Across Pre-Existing Horizontal Wellbores by E. Britton, Sundance Energy, et al. SPE 188509 Hydraulic Study of a Horizontal Well To Compare Dual Horizontal/Vertical vs. Single-Vertical Completion by Ahmed Alshmakhy, Abu Dhabi Company for Onshore Petroleum Operations, et al. SPE 191850 Drilling a 3200-m-Lateral-Length Horizontal Well in the Vaca Muerta Formation by Jonatan Medina, YPF, et al.

Kakovost lepilnega spoja med lesom in jeklom

The aim of the research was to determine the suitability of selected polyurethane and epoxy adhesives for structural bonding of wood and steel. We tested four polyurethane adhesives COSMO and two epoxy adhesives ERGO and XEPOX. The quality of the adhesive bond was evaluated by a shear strength test followed by one of the following exposure tests of the specimens: exposure to the standard climate with 65 % relative humidity and a temperature of 20 °C; exposure to humid climate with 87 % humidity and a temperature of 20 °C; and various exposures (soaking/cooking) in water. The results showed that the polyurethane adhesives studied in this work cannot compete with epoxy adhesives in terms of bonding quality. The epoxy adhesives provided excellent bonding properties in dry conditions, and proved to be potentially suitable for non-structural use in humid conditions. However, in order to use the selected adhesives in construction applications, it is recommended that the adhesive joint should be additionally reinforced with screws to ensure the reliability of the joint in the event of exceptional moisture or fire.

Thin-film lithium niobate-on-insulator waveguides fabricated on silicon wafer by room-temperature bonding method with silicon nanoadhesive layer.

Lithium niobate-on-insulator (LNOI) waveguides fabricated on a silicon wafer using a room-temperature bonding method have potential application as Si-based high-density photonic integrated circuits. A surface-activated bonding method using a Si nanoadhesive layer was found to produce a strong bond between LN and SiO2/Si at room temperature, which is sufficient to withstand both the wafer-thinning (LN thickness <5 μm) and surface micromachining processes used to form the strongly confined waveguides. In addition, the bond quality and optical propagation characteristics of the resulting LNOI waveguides were investigated, and the applicability of this bonding method to low-loss LNOI waveguide fabrication is discussed. The propagation loss for the ridged waveguide was approximately 2 dB/cm at a wavelength of 1550 nm, which was sufficiently low for the device application. The results of the present study will be of significant use in the development of fabrication techniques for waveguides with any bonded materials using this room-temperature bonding method, and not only LN core/SiO2 cladding waveguides.

Effect of Alloying Elements Gradient on Solid-State Diffusion Bonding between Aerospace Aluminum Alloys.

Three different bonding couples assembled by two commonly used aerospace aluminum alloys were bonded within the temperature range of 460–520 °C under 6 MPa for 60 min in vacuum atmosphere. The interface microstructure and alloying elements distribution of the bonded joints were determined by scanning electron microscope (SEM) and Energy Dispersive Spectroscope (EDS); the bond strength was evaluated by tensile-shear strength test. The results show the bond quality improved effectively as the bonding temperature increased. Compared with the 1420-1420 and 7B04-7B04 bonding couples, the 1420-7B04 couples obtained better interface integrity and higher bond strength, the highest shear strength for 1420-7B04 couple can be as high as 188 MPa when bonded at 520 °C. Special attention was focused on the 1420-7B04 couple, the diffusion coefficient of Mg at the original interface under different temperatures were investigated, the results show the diffusion coefficient increased obviously as the bonding temperature increased. A diffusion affected zone (DAZ) without continuous intermetallic phases formed due to the diffusion of alloying elements across the bonding interface. The combined action of temperature and alloying elements gradient resulted in the increase of alloying elements diffusion fluxes, which in turn promote the bonding quality through the accelerated shrinkage of interfacial voids.