Bond Quality Research Articles

Overmoulding of Additively Manufactured Titanium Inserts Using Polyoxymethylene (POM)—Evaluation of Bond Quality as a Function of Process Parameters

Due to their process-induced porous surfaces, additively manufactured structures are not optimized for applications in which friction is a key factor. To improve the frictional properties of additively manufactured titanium inserts of various thicknesses, two tribologically optimized POM materials, which differ in terms of filler composition and contents, were used to overmould the inserts. The titanium inserts were manufactured in two different building directions, resulting in a variation in surface roughness. The main challenge with respect to overmoulding is to maintain an even, thin plastic layer on the titanium insert. In order to evaluate the adhesion between plastic and metal, the interface is examined by optical microscopy and assessment of the peeling resistance. The peeling test shows that the overmoulded titanium inserts with a higher surface roughness are characterized by a higher peeling resistance. It is further revealed that the POM material with a special filler concept shows superior peeling resistance.

Evaluation and Optimization of Bypassed Oil in Carbonate Reservoir at Mature Field with Integration of Saturation Log and Cement Bond Quality

AA field is a unitized asset operated by Corporate Oil Company since May 2018. The main producing formation of AA field is a reef build-up carbonate reservoir. The field has been on production since 2004 with OOIP of 297 MMSTB. As of November 2019 the cumulative production was estimated 120.7 MMSTB with RF of 41%. The carbonate reservoir has properties with relatively high heterogeneity –both vertically as well as laterally – which leads to production variation of the wells. The production performance shows an estimated 30% decline and significantly increasing water-cut. The production data shows a much faster water production compared with the cumulative production, which is also the greatest challenge in the AA field.There are several key contributing factors for the water production in AA field:Water channeling behind casing due to poor cement bond. This is supported by Chan Plot analysis.Uneven production of the wells leading to varying water rise and introduces difficulty in water contact determination.Water coning due to production exceeding the critical rate.Several efforts have been performed to optimize production, namely: identification of the potential of remaining hydrocarbon (bypassed oil) in the wells by evaluating current saturation evaluation through downhole surveillance, estimation of current water contact and cement bond improvement.The preparation steps of the production optimization process are summarized below:Screening of Candidate WellsEvaluation of Cement Bond QualityWellsite Execution for Bypassed Oil EvaluationWell PreparationOptimum C/O Log to Evaluate Current Saturation and to Identify Bypassed Oil ZonesBypassed Oil Interval ProductionThis section discusses one of successful cases in the production optimization effort implemented in the AA- field.AA-12 wellThe last production of AA-12 well was 84 BOPD. Chan plot showed possibility of water channeling, which was supported by CBL result. The zone of existing perforation interval was indicated to have “free pipe” behind the casing. Remedial cementing was then performed until sufficient zonal isolation was obtained. After subsequent CBL confirmed good zonal isolation, C/O log was then performed. The C/O log result indicated several reservoir zones with potential bypassed oil. The new production interval was selected based on following consideration: So between 55-60%, height above current OWC of 185 ft (56 m), distance to the adjacent wells of 1306 ft (398 m), porosity 12-17% and Production test of the new perforation resulted in 2186 BOPD with 0% water-cut.

Caring for a Child with Cancer: The Role of Attachment, Self-Compassion and Social Support

ABSTRACT Background It is widely accepted that family caregivers are central to the future of cancer care and the impetus is to understand how best to support and empower them. Aims This study explored the role of the relationship between the caregiver and the child, the level of perceived support, and the self-compassion of the caregiver, on distress and wellbeing in mothers who were the primary caregiver for a child with cancer. Methods A self-report questionnaire survey of 255 mothers assessed perceived support, attachment to the child, self-compassion and a range of demographic variables including age, education, employment and time since diagnosis. Results A model was proposed and explored using Hierarchical Multiple Regression Analysis (HMRA) and tested more fully using Structural Equation Modelling. The results of both analyses support the model and show it to be an excellent fit for the data. Conclusions The findings suggest that the quality of the attachment bond with the child along with mother’s ability to be self-compassionate, combined with perceived social support may moderate the impact of care burden on perceived distress for mothers caring for a child with cancer.

Numerical simulation of the influence of bond strength degradation on the behavior of reinforced concrete beam-column joints externally strengthened with FRP sheets

Limited information is known about the effects of bond strength degradation during installation on the bond's quality and performance between fiber-reinforced polymer (FRP) reinforcement and substrate material. This research study's primary focus is to investigate the efficiency of the external FRP composites in rescuing the structural performance and controlling the mode of failure of the reinforced concrete (RC) beam-column joint with different bond strength degradation percentages nonlinear finite element analysis (NLFEA). Firstly, the RC beam-column model was validated against the published experimental results and then was expanded to consider the effect of the degradation percentages in bond strength between concrete and FRP composite (0 % (Fully bond), 10 %, 20 %, 30 %, 40 %, 50 %, 60 %, 70 %, 80 %, 90 %, and 100 % (control or un-strengthened joint). The structural performance was evaluated in terms of failure mode, stress distribution, pulling and pushing ultimate load capacity and corresponding displacement, horizontal load-displacement hysteretic loops, horizontal load-displacement envelopes, displacement ductility, energy dissipation, stiffness degradation, and equivalent hysteretic damping factor. The NLFEA results showed that the FRP strengthening technique with bond strength degradation percentages less than 30 % enhanced the cyclic performance (higher load capacity, larger horizontal displacement, higher displacement ductility, higher energy dissipation, and slower secant stiffness degradation). Also, the utilized FRP method with bond strength degradation percentage less than 30 % performed well in eliminating any surface debonding or buckling in the FRP composite because of the proper lateral support provided for the strengthening sheets. Finally, the bond strength degradation percentage less than 30 % could significantly enhance the deficient joints' seismic performance under strong beam-weak column conditions by changing its behavior to a more ductile one, including the beam flexural hinging. Moreover, the relocation of a plastic hinge in the beam provided more lateral strength for the joint specimens.

A study of solid-state bonding-by-hot-deforming mechanism in Inconel 718

• A bonding with restored integrity has been achieved in solid state at lower strain. • Joints being affected by both microstructure evolution and interface quality. • A new interface quality evaluation method with elongation of joints. • A new mechanism and model description in a unified manner for solid-state bond. Solid-state bonding shows irreplaceable advantages in joining similar and dissimilar materials with poor weldability compared with fusion welding methods. To widen its applications in manufacturing safety-critical structural parts, a sound bonding quality must be achieved under less strict conditions. In this work, the metallurgical bonding is formed by hot compressing two Inconel 718 parts to different strain levels at the temperature of 1150 °C, strain rate of 0.1s −1 under a low vacuum. Full tensile strength and ductility comparable to the parent materials have been achieved for the first time by 0.5 engineering strain. The severe plastic deformation at hot temperature rapidly bonds the two parts by effectively closing the interface micro-voids, breaking up the oxide film, and in the meantime, accelerating the grain boundary(GB) migration through the dynamic recrystallization(DRx). Based on these observations, a theoretical model is proposed to describe the bonding process under hot deforming condition and the achieved relative interface bond quality, in which the cohesion between oxide-oxide and oxide-metal is assumed, and impairing effect of remaining dispersed oxides is minimized with the attempt of introducing a strain-amplifying factor. The insights and model provide the basis for further understanding of the solid-state bonding-by-hot-deforming under practical conditions and explore its wider application with ideal joint integrity.

The Influence of the Roll-Laminating Process on the Bonding Quality of Polymer-Coated Steel Interface

Polymer-coated steel (PCS) is a new type of metal packaging material under development, which has better performance in saving resources, energy, and environmental protection. The lamination process has an important influence on the bonding quality of the PCS interface. PCS samples under different lamination temperatures and lamination speeds were prepared through experiments. A binding rate is defined to represent the real bonding area of the PCS interface. The micro-scratch tester and scanner are used to study the influence of the lamination process on the bonding rate and bonding strength of the PCS interface. It is proposed that the bonding rate and bonding strength of the PCS interface increases with the increase of lamination temperature and increases with the decrease of lamination speed. The PCS interface bonding rate and bonding strength are positively correlated. SEM and DSC experiments revealed the cause of bubbles on the PCS surface. It is proposed that controlling the uniformity of the TFS surface temperature can reduce the quality defects of PCS surface bubbles. Relevant research results bring guiding significance for the formation of enterprises.

Non-destructive testing to characterize interlayer bonds of idealized concrete additive manufacturing products

We examine non-destructive testing (NDT) techniques that characterize the interlayer bond quality of idealized 3-D printed concrete, simulating a layup bond, in-situ. An experimental study evaluates four NDT methods (x-ray radiography, ultrasonic pulse velocity (UPV), vibration resonance, and multi-element array ultrasonics) to idealized, layered concrete specimens that simulate layers of a 3-D printed structure. The interlayer bond strengths of the specimens were measured directly using split-prism load testing. X-ray radiography and multi-element array ultrasonic test data demonstrate best correlation with measured interlayer bond strengths. We used multi-element array ultrasonic test data to classify bond interface quality into well bonded, weakly bonded, and debonded cases.

Cement bond evaluation using well logs: A case study in Raniganj Block Durgapur, West Bengal, India

Cement bond logs (CBL) and variable density log (VDL) are one of the vital logging techniques used to evaluate cement-casing-formation bonds before the well testing or execution of the production operation in the well. These logs are also crucial during the workover operation to maintain the integrity of the well. The logging techniques provide a clear view of the quality of cement bonds with casing and formation. The microannulus and other deviations in bonding between the cement and the casing or formation are recorded using this technique. Therefore, this technique is used by the regulatory authorities worldwide for the determination of the cement bond with casing and formation. In this paper, the CBL/VDL logging technique was used to determine the bonding between cement and casing and cement and formation at two different CBM wells from 850 to 1600 m depths in the Raniganj block of Durgapur, West Bengal. Two well, namely, A and B, were analyzed to determine the cement-casing-formation bonds in the study area's coal seam zone. The analysis was carried out at normal and pressure pass to investigate the integrity of the well using the CBL/VDL data. The normal and pressure pass in well A indicated the presence of microannulus in the bonding between cement and casing/formation in the coal seam zone. The corresponding analysis of well B showed poor cement and formation bond at the coal seam zone during the normal pass but good bonding after the pressure pass. Thus, it was observed that the CBL/VDL data were capable of determining the cement-casing-formation bonds in both the well of the study area and the well's integrity.

De-bonding assessment of rebars using an ultrasonic method with laser vibrometer tests and numerical simulations

“Perfect bonding” of reinforcement steel and concrete is a desired condition in practice, but any reinforcement defect (corrosion, crack) or concrete distress reduces the quality of steel-mortar bonding. Degradation of steel rebar – concrete bond because of steel corrosion is the most common process leading to reduction in service capacity or failure in reinforced concrete (RC) structures. Corrosion-related bond degradation decreases the RC element's strength and also tends to accelerate the corrosion process. Common practice for de-bonding detection is invasive, often destructive, and is not satisfactory for practical use in RC condition assessment.In this study, an experimental and mathematical simulation approach based on the ultrasonic guided wave method is developed to non-destructively distinguish the differences in bond quality for corrugated and smooth steel bars embedded in concrete cylinders. For the experiments, a highly sensitive laser vibrometer is used to capture displacement versus time signals. Numerical simulation is verified first by comparing numerical results with analytic equations, and then by comparing with experimental results. Results from the tests and simulations confirm that when there is “perfect bonding” between the steel bars and mortar, wave energy leaks easily into the mortar and higher frequency waves dissipate before arriving at the end of the bar. In contrast, for poorly-bonded specimens, high frequency displacement waves travel mostly through the steel: an amplitude diminution of five times is observed for the poorly-bonded experimental specimens. Frequency analysis also showed that there is a significant drop in overall energy content of the signal for perfectly-bonded samples in comparison to de-bonded samples because of more wave energy leakage in a broad spectrum. This study shows that the acoustic wave propagation method can reveal the degree of steel reinforcement de-bonding in a non-destructive manner. Although there will be challenges in application of this method in the field, it is most likely to be useful on a year-to-year basis to evaluate progressive de-bonding from corrosion of RC structures for better risk management analysis.

Optimisation and field assessment of poroelastic wearing course bond quality

Compared to typical asphalt mixtures, poroelastic mixtures are characterised by high porosity and high flexibility, which are desirable for traffic noise reduction. However, the same properties increase the risk of debonding from the lower layer, which is a significant source of premature damage. The study investigates which of the factors – tack coat agent, type and texture of the lower layer – have the greatest impact on interlayer bonding quality. From 27 variants of interface bond techniques investigated in laboratory, 8 were selected and constructed on two full-scale test sections. Monotonic direct shear loading and cyclic direct shear loading tests with normal force were used for this purpose. The tests indicated that softer bitumen used for the tack coat and the milled texture of the lower layer improves bond quality. However the appropriate laying compaction has the major influence. Poroelastic mixtures are much more sensitive to technological imperfections than standard asphalt mixtures.

Effect of Curing Time on Bond Failurerct Based on Two Light Cure Units used in Bonding Orthodontic Brackets

In routine orthodontic practice, we usually aim at having a reduced chair side time while bonding as well as an appropriate bond strength for the brackets till the treatment completion. This is dependent on several factors which affect the quality of bond obtained between the bracket and the tooth structure. One such is the depth of cure by using different curing lamps. This study aimed at comparing the rate of bracket bond failure of brackets when bonded using light cure units with different curing time (3S and 20S). This was a randomized control trial performed as a split mouth study among patients who came for orthodontic correction of malocclusion. Among them, 24 patients were selected and split mouth study was performed. For this dental arch of each patient was split among two groups (Group A and Group B). MBT Stainless steel orthodontic brackets were bonded in both the dental arches. Group A was cured with 3 second light cure unit in I and III quadrant and 20 second light cure unit in I and III quadrant and vice versa for group B. The number of bond failures at the end of 4 weeks and 8 weeks were assessed. Bond failures among both the groups were summarized. Independent t test was used to assess the statistical difference between the groups. Overall it was evident that the bond failure was greater clinically in the group cured with 20 second curing light especially in the mandibular arch and the posterior teeth

Better Automatic Interpretation of Cement Evaluation Logs through Feature Engineering

Summary We investigate systems to automatically interpret cement evaluation logs using supervised machine learning (ML). Such systems can provide instant rough interpretations that may then be used as a basis for human interpretation. Here, we compare the performance of two approaches, one previously published and one new. The previous approach is based on deep convolutional neural networks (CNNs) that autonomously learn to extract features from well log data, whereas the new approach uses feature engineering, in which we use our own domain knowledge to extract features. We base this work on a data set of approximately 60 km of well log data. Specialist interpreters have classified these logs according to the bond quality (BQ; six ordinal classes) and hydraulic isolation (HI; two classes) of solids outside the casing. We train the ML systems to reproduce these reference interpretations in segments of 1 m in length. The CNNs directly receive log data as a collection of 2D images and 1D curves. In the feature-engineering approach, we combine the extracted features with various classifiers. For BQ, the CNNs' interpretation exactly matches the reference 51.6% of the time. It does not miss by more than one class 88.5% of the time. For HI, the CNNs match the reference 86.7% of the time. The best-performing feature-based classifier, which is an ensemble of individual classifiers, provides better results of 57.4, 89.5, and 88.9%, respectively. Our results indicate two main reasons why feature-based classifiers may perform particularly well on this task. First, there is some subjectivity inherent in the well log interpretations that are used to train and test ML systems. Second, well logs comprise many different and complex pieces of data. For these reasons, this data set may be particularly liable to overfitting. This may favor approaches based on feature engineering, where we apply our domain knowledge to extract a few pieces of essential information from the data instead of leaving the job of understanding the data to an ML system that may misinterpret spurious patterns as generalizable. It may also favor simpler classifiers with less overfitting capacity. This paper shows how petroleum researchers and engineers can implement automatic interpretation systems for cement evaluation logs using ML methods that are easier to apply and deploy while also performing better than an approach based on autonomous feature extraction. This approach could also be adapted for automatic interpretation of other types of well log data.

Trajectories of Childhood Maltreatment and Bullying of Adolescents in South Korea

Child maltreatment has a critical impact on the lives of children. Maladaptive parenting may interrupt the process of establishing healthy peer relationships as the quality of parent-child bonds determines positive or negative child outcomes. Although maladaptive parenting is known as a risk factor for predicting bullying perpetration and victimization, there has been little consideration of its developmental influences. We aimed to investigate the association between trajectories of parental maltreatment and peer bullying experiences from childhood to adolescence in Korea. Four waves of the nationally-representative Korean Children and Youth Panel Survey were used to assess parental abuse and neglect from grades four to seven (N = 2179; age range from 10–11 to 13–14). Latent class growth analysis identified trajectories of maltreatment, and logistic regression highlighted the relationship between derived trajectories and bullying engagement. Three latent groups of maltreatment trajectories were found and were named as low (59.26%), high neglect (30.02%), and high abuse (10.72%). Results from the logistic regression indicated that the high abuse trajectory was more strongly associated with higher rates of both bullying perpetration and victimization than the low trajectory. This study has implications for identifying long-term influences of abusive parenting in contrast to neglectful parenting over the course of childhood for engagement in adolescent bullying behavior. Findings may provide insights for prevention, intervention, and school bullying policies regarding developmental trajectories of maladaptive parenting.

DAMPAK PENGUMUMAN BOND RATING TERHADAP RETURN SAHAM DAN VOLUME PERDAGANGAN SAHAM PERUSAHAAN YANG TERDAFTAR DI BURSA EFEK INDONESIA

A bond rating is a rating that independent agencies issue to measure the credit quality of a particular bond. The bond rating measures the financial strength of the company issuing the bond, and its ability to make interest payments and repay the principal of the bond, when due. The objective of this research was to give empirical evidence about the effects of stock return and stock trading volume on bond rating announcements partially. The objective of this research was also to give empirical evidence about the differences between stock return and stock trading volume before and after bond rating announcements. This research examined 59 stock issuer on Indonesia Stock Exchange which announced bond rating during period 2015-2017. Data were analyzed by paired sample t-test and simple regression analysis. The results show that there are no differences between stock return and stock trading volume before and after bond rating announcements. The results also show that bond rating announcements does not efect both stock return and stock trading volume partially.

Testing Low-Melting-Point Alloy Plug in Model Brine-Filled Wells

Summary Low-melting-point bismuth- (Bi-) based alloys have recently been proposed for plug-and-abandonment (P&A). Previous experiments have shown the feasibility of BiSn [58-wt% Bi and 42-wt% tin (Sn)] and BiAg [97.5-wt% Bi and 2.5-wt% silver (Ag)] alloy plugs in moderate temperature wells, both across shales and across the shale/sandstone sequence. These were validated in linear and cylindrical wellbore cavity geometries for various differential setting pressures for alloy over air. Until now, all of the experiments for setting alloy plugs have been conducted with air as the wetting fluid. Given the lack of adhesion between minerals and alloy, our concept for providing bond strength and integrity has hinged on providing a bicontinuous structure through alloy penetration into the pore network. For shales, with a positive setting pressure, anchors on the surface, in lieu of pores, have proven to be adequate. With results obtained under excess alloy pressure, we have quantified the effect of setting pressure on the alloy/shale bond quality. With brine as the wetting fluid, imposing an excess pressure on the alloy has not been demonstrated previously. This paper is the continuation of our previously published papers (Zhang et al. 2020, 2021), and our objective here is not only to show the possibility of forming a plug under brine but also to quantify the plug’s quality with and without an excess alloy pressure. We first describe an apparatus that controls alloy and brine pressures independently through a semipermeable piston assembly and demonstrate forming alloy plugs in a brine-filled borehole cavity. Based on pressure decay tests across the plug, we demonstrate that wellbore integrity is possible only with a positive alloy pressure over that of brine.

DETERMINATION AND MODELLING OF BOND PROPERTIES OF SYNTHETIC MACRO-FIBRES IN CONCRETE

Bond behaviour of a synthetic macro-fibre in concrete is the object of this research. The bond strength and stiffness are the parameters characterising the bonding mechanism that determines the efficiency of the reinforcing material. However, there is no general methodology developed to evaluate fibre efficiency. There also exists neither a straightforward procedure to estimate the bond quality of a synthetic macro-fibre nor a reliable numerical model to simulate the bond behaviour of such fibres. In this work, the bond mechanisms of 40 mm long synthetic macro-fibres are investigated using pull-out tests: 16 concrete cubes were made for that purpose. One type of synthetic macro-fibre available at the market is considered. In each test sample, three fibres were inserted perpendicular to the top and two side surfaces; two bonding lengths (10 mm and 20 mm) were used. A gripping system was developed to protect the fibres from local damage. A physically non-linear finite element model of the pull-out sample was developed. A bond model was proposed to simulate deformation behaviour of the fibres.

Fibre-reinforced polymer laminate–concrete bond check with ground penetrating radar

Externally applied carbon-fibre-reinforced polymer (CFRP) laminate is a viable, economic and durable option for strengthening deteriorated, damaged or under-designed concrete structures. Effective stress transfer at the CFRP–concrete interface is an important consideration and quantitative on-site inspection of CFRP application quality is still a challenging issue. In this study, a ground penetrating radar scanning approach was used to examine the bond quality in small-scale concrete beams with flexurally applied CFRP laminates. The parameters considered included the concrete surface roughness, concrete surface voids, epoxy thickness and CFRP type. A three-point bending test and numerical modelling were used to develop simple quantitative relationships between the scanning results and the parametric combinations. Non-destructive evaluation techniques are convenient and provide valuable information for the prediction of the interfacial bond quality and the actual capacity contribution of the CFRP laminate, which will allow a higher confidence level in CFRP application quality and better quality control of concrete structures.

Diffusion bonding of 304 austenitic stainless-steel using pressure pulses

Abstract The influence of bonding temperature during impulse pressure assisted diffusion bonding on characteristics of AISI 304 austenitic stainless steel has been reported in this paper. Austenitic stainless steel sheets were joined by impulse pressure assisted diffusion bonding in a temperature range of 850–950 °C. The bond interface was analyzed by tensile shear testing, optical microscope, field emission scanning electron microscope. The soundness of the diffusion bond was evaluated by calculating the interface bonding ratio (ratio of void free interface length to the total interface length). The effect of diffusion bonding temperature on tensile properties and interface bonding ratio was investigated. The maximum tensile shear load carrying capacity of the diffusion bond obtained was 34.42 kN at 950 °C. The structural analysis revealed good joint quality of the diffusion bonds and 91.25% bonding interface ratio at 950 °C bonding temperature.

Emergency care under the magnifying glass: a review of ethnographic studies in the scientific literature on hospital emergency services.

The article presents a review of ethnographic studies in the scientific literature on hospital emergency services, with the objective of systematizing the studies and their principal findings, referring to the health-disease-healthcare process in hospital emergency services from an ethnographic perspective. An integrative literature review was performed of studies published in Argentine and international indexed journals and in the following electronic databases: PubMed, VHL, Scopus, Redalyc, and SciELO. The corpus of the analysis consisted of a total of 69 articles, which were submitted to content analysis, having identified the following analytical dimensions: quality of care, communication and bonds, subjectivity, application of information technologies, methodological reflection, patients' experiences and practices, decision-making, and violence. The results allowed identifying a process that differs from guidelines and protocols, in which healthcare workers' subjective aspects, communication and interpersonal relations, and working conditions shape, orient, and condition the treatment and care provided in the hospital. The article thus highlights the approach to subjective aspects in health studies, to understand not only health workers' perspectives and experiences but also the persistent barriers to providing better quality of care, complexifying a problem ignored by a large share of the analyses.

Non-Technical Skills in Social Networks: The Spread of Safety Communication and Teamwork in a Warehouse.

Safety at work should be considered as the result of the daily interaction of operators. The present research wants to analyze which factors are involved in the development of social networks about safety at work. We assumed that two relational non-technical skills, such as safety communication and safety team member support, affect the in-degree and out-degree bonds of workers in social networks. One hundred and eight workers of a warehouse were the participants of the research, in which they were asked to fill out a self-reported questionnaire. Multiple linear regression analysis was used to test the hypotheses. Results confirmed that safety communication and safety support skills play a role in determining the quantity and the quality of social bonds that workers can create at the workplace. To be specific, while safety communication was found to be associated with out-degree centrality (b = 0.24; p = 0.01), a nonsignificant relationship was found for in-degree centrality. In contrast, safety team member support was found to be associated with in-degree centrality (b = 0.28; p = 0.04). In other words, on the one hand, it was found that high levels of safety communication skills are associated with the tendency of workers to proactively search for colleagues with whom they can share information about safety. On the other hand, workers with high levels of safety support skills tend to be considered as reference points in terms of safety by colleagues, who are more prone to look for their help. Implications for both scientists and practitioners are discussed.