Bond Quality Research Articles

Monetary evaluation of the reduced service life of asphalt pavements caused by the interlayer bond

The sustainability of asphalt pavements is highly depending on the quality of the interlayer bond (IB) between the different asphalt layers. In this project a complicated apparatus for cycling testing of the interlayer bond has been developed in order to determine the shear stiffness at the interface between asphalt layers taking into account the combined effect of varying and repeated traffic loading, acceleration and braking processes and temperature. A universal master function for analytical assessment of the IB shear stiffness has been established for any IB condition using the experimental results. Another function for completely fatigued IB has been developed as well. Both functions have been implemented into a finite element program to estimate the fatigue status of asphalt pavements for different bond qualities over a service life of 30 years using the German method for computational design according to RDO Asphalt 09. It has been succeeded to make a monetary evaluation of the reduced service life of asphalt pavements caused by interlayer bonds of different quality and to assess the construction cost penalty.

Parametric optimization for rehabilitation of pipes with adhesive bonding

This work deals with the optimization of process parameters for rehabilitation of the pipe through-wall hole defects using adhesive bonding. Epoxy-based nonstructural adhesive (NSA) and structural adhesive (SA) combination, precure temperature, bond length, and surface preparation were considered as the parameters. The optimization of parameters directly on pipes is an expensive and time-consuming process. Hence, stainless steel and carbon fiber-reinforced polymer (SS-CFRP) composite single-strap joint was considered. The equivalent loads that were acting during the hydrostatic pressure test were applied to the SS-CFRP joint and its parametric effect on bond strength was studied. The stress distribution along the adhesive layer length has been derived analytically. The surface roughness of prebond surfaces was measured using a 3-D microscope. The quality of the adhesive bond was evaluated using nondestructive testing (digital radiography). The damaged pipe was rehabilitated with optimized parameters and its hydrostatic pressure resistance was tested according to ISO/TS 24817 standards. From the results, it is observed that the rehabilitated pipe with optimized parameters was able to sustain a maximum of 79% of its allowable pressure.

Non-linear behaviour of concrete beams reinforced with GFRP and CFRP bars grouted in sleeves

The low-quality bond between fibre reinforced polymer (FRP) bars and surrounding concrete has drawn the attention of many researchers. The use of high-strength materials such as the grout in the intersection of FRP bars and surrounding concrete can effectively prevent any slippage once they are in contact and subsequently increase the bond quality. Therefore, this study was numerically focused on the flexural behaviour of concrete beams reinforced with glass fibre reinforced polymer (GFRP) and carbon fibre reinforced polymer (CFRP) bars, grouted only in the pure bending zone and along the whole beam length. The numerical outputs revealed that the grouted GFRP bars propagated the maximum principal stress in high-strength concrete beams, but not as much as that in normal-strength concrete specimens. In addition, the stress distribution in the grout, created only in the pure bending zone, was nearly constant at the ultimate moment. For the grout, developed along the whole beam length, this stress increased by approaching the mid-span of the concrete beam. Furthermore, at the ultimate moment, the tensile stress of 12-mm diameter CFRP bars was about 3.5 times more than that of the 16-mm diameter CFRP bars, leading to the generation of difference between failure modes of concrete specimens reinforced with various diameters of CFRP bars.

A Qualitative Study of the Working Alliance between Patient and Community Mental Health Nurse during Interpersonal Community Psychiatric Treatment

In the Netherlands, long-term community psychiatric treatment for patients with a severe mental illness (SMI) is poorly developed and lacks a structured, goal-centered approach. Often this form of treatment is provided by community mental health nurses (CMHN’s).Especially in the group of nonpsychotic patients with SMI, it often leads to care-as-usual with limited proven interventions and an unstructured treatment. Interpersonal Community Psychiatric Treatment (ICPT) was developed to provide this group of patients a focus, a theoretical view, and a methodological structure. A pilot study has been conducted on ICPT. As a result, a randomized controlled trial (RCT) was recently conducted in which this study is part. The pilot study showed improvement on a number of treatment outcomes. However, the working alliance (WA) experienced by the patients, although not significant, was considered to be decreased. The aim of study was to gain insight into how the ICPT-elements shape the WA and the possible self-determination of patients in general.The main part of this mixed-methods study was a qualitative study with a Grounded Theory approach. For the selection of the participants, quantitative data from the current RCT has been used. Semistructured interviews have been conducted with 13 participants, divided over three mental health institutions throughout the Netherlands. Interviews and analysis were alternated, so that the interview topics were developed by constant comparison.Eleven participants were female and 11 participants received social benefit. Six of the participants were above 50 years of age. Four participants suffered either from a depressive or anxiety disorder. Seven participants had a borderline personality disorder. The results are linked to Bordin’s theory of the therapeutic alliance, which is agreement on therapeutic tasks, agreement on therapeutic goals, and the quality of the personal bond. The WA could be analyzed from three different perspectives: mutually agreed on goals, tasks, and experienced interpersonal relationship. ICPT had limited influence on the mutually agreed on goals and interpersonal relationship but mainly on the mutually agreed on tasks. In daily practice, ICPT may have a positive influence on the perceived WA.The main factors that affected the perceived WA during ICPT were the tasks that had been mutually agreed on, the use of an agenda, the structure of the sessions, the alliance between the CMHN and the patient, and the patient’s own self-determination. There was a limited influence on the mutually agreed on goals and the quality of the personal relationship between the CMHN and the patient. The present research revealed valuable information about the significance of the WA in ICPT and the opinions of the respondents about ICPT and information about what might be helpful or unhelpful in their relationship with their CMHN.

Temperature-dependent peel performance of adhesively rebonded hybrid joints

Structural bond integrity of reassembled (adhesively bonded) hybrid joints is assessed through floating roller peel tests in remanufacturing. Improper peeling, inconsistencies in the surface preparation and residual adhesive significantly affect the floating roller peel behavior of adhesively bonded and rebonded joints. In this work, the peel behavior of hybrid joints consisting of glass fiber reinforced polymer (GFRP) composite, Ti-6Al-4V adherends (with different surface preparations) and structural epoxy adhesive as a function of temperature was measured. Further, the peel performance of rebonded joints made up of thermo-mechanically debonded composites without removing the residual epoxies (R1) and reconditioned with multiple surface preparation techniques (R2) were evaluated. In this paper, the effect of residual adhesive on the peel load, failure modes as a function of temperature and flexural deformation of the Ti-6Al-4V adherend were studied. Improper surface reconditioning of debonded composites resulted in poor bond quality and peel strength as compared to the pristine joints.

Effect of strain rate on plastic deformation bonding behavior of Ni-based superalloys

Plastic deformation bonding (PDB) has emerged as a promising solid state bonding technique with limited risk of phase transformations and residual thermal stresses in the joint. In this study, the PDB behavior of IN718 superalloy was systematically investigated by performing a series of isothermal compression tests at various processing conditions. It was revealed that, with increasing PDB strain rate at 1000 °C, different extents of dynamic recrystallization (DRX) occur in the bonding area of IN718 joints. The extent of DRX, average size of DRXed grains, and a newly proposed “interfacial bonding ratio (ΨBonding)” parameter (to quantify the bond quality) were initially reduced with increase in the strain rate up to 0.1 s−1 and later increased at further higher strain rates. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) based interfacial microstructure analyses indicated that the quality of the bonded joints is closely related with the development of fine DRXed grains at the bonding interface with the increasing strain, which promotes adiabatic temperature rise. It was revealed that the initial bulging and subsequent migration of the original interfacial grain boundary (IGB) were the main mechanisms promoting DRX in the well bonded IN718 superalloy joints. Moreover, the mechanical properties of the bonded joints were not only controlled by the recrystallized microstructure but also depended upon the Bonding parameter of the joints.

Observed infant-parent attachment and brain morphology in middle childhood– A population-based study

Poor quality of the early infant-parent bond predicts later child problems. Infant-parent attachment has been suggested to influence brain development, but this association has hardly been examined. In adults, larger amygdala volumes have been described in relation to early attachment disorganization; neuroimaging studies of attachment in children, however, are lacking.We examined the association between infant-parent attachment and brain morphology in 551 children from a population-based cohort in the Netherlands. Infant-parent attachment was observed with the Strange-Situation Procedure at age 14 months and different brain measures were collected with magnetic resonance imaging at mean age 10 years.Children with disorganized infant attachment had larger hippocampal volumes than those with organized attachment patterns. This finding was robust to the adjustment for confounders and consistent across hemispheres. The association was not explained by cognitive or emotional and behavioral problems. Disorganized attachment did not predict any other difference in brain morphology. Moreover, children with insecure organized infant attachment patterns did not differ from those who were securely attached in any brain outcome.Causality cannot be inferred, but our findings in this large population-based study provide novel evidence for a long-term association between the quality of infant-parent attachment and specific brain differences in childhood.

Optimization of process parameters for rehabilitation of pipes through adhesive bonding: experimental study

In many industries maintenance and repairing of pipes are crucial elements to engineers. The processes may consume a lot of money and time. Conventional methods like welding, riveting etc. may damage the base material or some times the pipe may carry inflammable fluids which can not be possible to repair by conventional methods. In such a case, adhesive bond may provide an alternative solution to the pipe repair or strengthening applications. The present work focuses on the optimization of process parameters which enhances the adhesive bond capacity (Tensile shear load) between carbon fiber reinforced polymer (CFRP) composite patch and SS (SS 304) plates. Epoxy resin and adhesive combination, pre cure temperature and surface preparation was considered as parameters. The surface roughness of pre-bond surfaces was measured using a 3D-microscope. The quality of the adhesive bond was evaluated using non-destructive testing (Digital Radiography) before performing tensile test. The failed surface morphology was studied using FE-SEM images. The optimal parameters were derived form the tensile test data of the adhesive joint. The bond capacity for lateral loadings was also studied using a three point bending test at the derived conditions. These parameters were also applied to rehabilitate the damaged pipe and its ability was evaluated through hydrostatic pressure test. From the results, it was observed that these parameters hold good for pipe rehabilitation also.

Co-consolidation of CF/PEEK tape-preforms and CF/PEEK organo sheets to manufacture reinforcements in stamp-forming process

Co-consolidation is considered one effective joining method to allow novel types of integral structures to be manufactured. In this study, carbon fiber reinforced Polyether-Ether-Ketone partially consolidated tape preforms were co-consolidated with carbon fiber reinforced Polyether-Ether-Ketone organo sheets in stamp-forming process. Interlaminar bond quality of both joining partners is validated in double cantilever beam test. Results exhibit average interlaminar fracture toughness of 2.54 kJ/m2 for stamp-forming specimen, which exceeds interlaminar fracture toughness of reference samples manufactured in autoclave being 1.79 kJ/m2. Further examinations on specimen morphology and mechanical properties indicate distinct assignments to process characteristic cooling rates, which coincides with studies from literature. Accordingly, high cooling rates—as evident in stamp-forming process—are allocated to high toughness, low crystallinity and low bending modulus, causing high interlaminar fracture toughness. Investigations on laminate quality reveal maximum void content of 1.58%.

Impact of multi-dimensional vibration trajectories on quality and failure modes in ultrasonic bonding

Abstract Ultrasonic joining is a common industrial process. To build electrical connections in the electronics industry, uni-axial and torsional ultrasonic vibration have been used to join different types of workpieces for decades. Many influencing factors like ultrasonic power, bond normal force, bond duration and frequency are known to have a high impact on bond quality and reliability. Multi-dimensional bonding has been investigated in the past to increase ultrasonic power and consequently bond strength. This contribution is focused on the comparison of circular, multi-frequency planar and uniaxial vibration trajectories used for ultrasonic bonding of copper pins on copper substrate. Bond quality was analyzed by shear tests, scanning acoustic microscopy and interface cross-sections.

Micro-chemo-mechanical features of ultra-high performance glass concrete (UHPGC)

The development of Ultra-High Performance Concrete (UHPC) opened new research directions for enhancing the architectural design, sustainability and serviceability of concrete structures. However, the costs and resource intensiveness trigger the need for innovative UHPC mix design incorporating alternative materials, such as post-consumption Glass Powder (GP). This works aims at disclosing the microstructure features of UHPGC, in which the constituents can be partially replaced by different fineness of GP without impacting the long-term strengths. By using the latest NI-QEDS technique (coupling NanoIndentation and Quantitative Energy-Dispersive Spectroscopy), as well as image analysis applied to EDS chemical mappings, it was possible to investigate mechanical properties of the microstructure constituents and their volume fractions. A conventional UHPC microstructure was compared to a similar system with 30% replacement of cement by GP and to another system with 50% replacement of silica fume by Fine GP (FGP). The results showed the key role of GP anhydrous particles contributing to the rigid skeleton of anhydrous inclusions, as well as their bond quality with the surrounding cement paste. The reduction of cement and silica fume was thus possible without impairing the micromechanical properties of the hydrates, by improving the particle packing density in the hardened state. As major conclusion, replacing cement and silica fume with GP and FGP without impairing both micro-scale and macro-scale mechanical properties provides a promising means to reduce the environmental footprint of current UHPC mix design.

Optimization of Copper Thermocompression Diffusion Bonding under Vacuum: Microstructural and Mechanical Characteristics

The optimization of the autogenous diffusion copper bonding via thermocompression at vacuum environment was investigated. The influence of various bonding parameters on the interdiffusion efficiency was studied in detail at the micro (SEM-EBSD) and nano (TEM) scales. Bonding at 1000 °C for 90 min under pressure (10 MPa) presented optimum structural and mechanical results. Under these conditions, interdiffusion phenomena were observed at a significant extent through the swelling transformation of existing fine grains or the formation of equiaxed copper grains with an orientation parallel to the bond interface. Transmission electron microscopy revealed the importance of the grain size of the base material on the bond quality. In the regions with fine-sized copper grains, the formation of small equiaxed recrystallized twins was observed. Their length within the bonding zone was in the order of 200 and 400 nm. On the contrary, in the regions with coarse grains the interdiffusion was poorer. The processing temperature and duration presented a significant effect on the bonding strength (BS). BS exceeded 100 MPa in case of processing conditions of T ≥ 850 °C and t ≥ 60 min, while the maximum BS value achieved (≈180 MPa) was comparable with the respective value of the base material. The microhardness of the optimum bond reached 55 HV—slightly higher in comparison to the hardness of the initial copper material. The results indicated that the proposed thermocompression process is appropriate for the production of Cu-Cu bonded structures that can be potentially used as electrical components under mechanical stress.

Novel Transient Liquid Phase Bonding for High-Temperature Automotive Power Electronics Systems

Abstract This paper demonstrates the concept and fabrication process for a novel (copper, nickel)–tin, (Cu, Ni)–Sn, transient liquid phase (TLP) high-temperature bond that exploits the addition of a pure aluminum (Al) core layer for die attachment in a power electronics power card structure. The bond quality and composition of the bond layer are characterized using confocal scanning acoustic microscopy (CSAM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The experimental results indicate that the material composition and established fabrication process enable a crack-free bond that exhibits a void fraction of 2% or less. Compared to a traditional foil-based single-layer TLP bonding system, the proposed foil-based TLP/metal laminated structure displays ∼60% reduction in thermally induced mechanical stress built-in after fabrication, as verified through steady-state thermal stress simulations.

Laboratory shear bond test for chip-seal under varying environmental and material conditions

ABSTRACT Ideally, a complete bond between the chip-seal and asphalt pavement is achieved during the chip-seal application. However, complete and total bonding is unlikely due to environmental and material conditions. Therefore, it is critical to understand the bond qualities under varying environmental and material conditions, which is also beneficial for cleaner production of chip-seal applications. The shear bond strength is a crucial indicator for revealing the bond qualities of chip-seal with asphalt pavement. The objective of this study is to develop a laboratory approach to characterise the shear bond strength of a chip-seal application with the asphalt pavement. It is achieved by developing a laboratory approach to the shear bond test (SBT). This study investigated the shear bond strength between chip-seal and asphalt pavement of several asphalt-aggregate combinations and different asphalt-emulsion application rates. Also, in order to characterise the influence of temperatures and freeze–thaw cycles on the durability of chip-seal, several test temperatures, and the multiple freeze–thaw cycles were applied in the proposed SBT. The laboratory test outcomes recommended that the weak shear bonding of chip-seal with asphalt pavement is in part because of the multiple freeze–thaw cycles suffered and the raw materials used.

Acoustic analysis of ultrasonic assisted soldering for enhanced adhesion

Ultrasonic soldering utilizes high-intensity acoustic fields to induce cavitation in the solder melt in order to (i) bond dissimilar materials and (ii) improve solder joint strength. The acoustic energy transfer from the piezoelectric transducer (PZT) into the liquid solder pool is critical in both understanding and optimizing this process. We use finite element analysis of the acoustics and compare with experiment. Our finite-element modeling approach is two-pronged; (i) we develop a one-dimensional model that is used as a design tool to optimize the solder stack geometry to match the transducer frequency for maximal acoustic energy transfer and (ii) we use a three-dimensional model to compute the frequency response in the solder stack assembly (solid acoustics) and the acoustic pressure in the liquid solder pool (solid-fluid interaction). The acoustic pressure is a proxy for cavitation and therefore bond strength. Our simulations show the acoustic pressure rapidly decreases as the height of the solder tip above the substrate surface increases, which correlates with controlled experiments that show the solder bond quality also decreases with increasing tip height.

Teologie di genere, un appello esigente

This article aims to clarify that there is no such thing as a ‘feminine theology’, but a complex panorama, in which women, with their particular differences, take the floor as subjects. Though recent in academic terms, gender theologies have a long history and have developed in such a way as to draw attention to how a culture signifies and symbolizes to show that the accomplisment of the Kingdom of God relies on the quality of inter-human relational bonds. With a distant masculinity, then surreptitiously made into a universal paradigm, and with a model of femininity that oscillates between Eve and Mary, the theological world shows itself to be manifestly disturbed: there is a desperate need for an inclusive way to talk about God.

A Pilot Study of the Relationship Between Pregnancy and Autoimmune Disease: Exploring the Mother's Psychological Process.

Autoimmune disease mainly affects women in their reproductive years and has a significant impact on childbearing. Pregnancy can induce an improvement of the mother’s symptomatology in some diseases such as rheumatoid arthritis while exacerbating or having no effect on other autoimmune diseases as multiple sclerosis (Borchers et al., 2010). This uncertainty can affect the process of psychological reorganization, which leads to the achievement of a maternal identity. The quality of the mother-fetus emotional bond is considered particularly relevant for the subsequent attachment relationship and the psychological development of the infant (Ammaniti et al., 2013). In the last trimester of pregnancy, 15 women with different autoimmune diseases were interviewed using the IRMAG-R (Ammaniti and Tambelli, 2010). They also completed a battery comprising: PAI (Della Vedova et al., 2008); MAAS (Busonera et al., 2016); DAS (Gentili et al., 2002); PBI (Scinto et al., 1999); MSPSS (Prezza and Principato, 2002); DERS, (Giromini et al., 2012); CES-D (Fava, 1983); HCR-TS (Bova et al., 2012). All interviews were audiotaped, transcribed verbatim, and analyzed by Atlas.ti. The results show that women with autoimmune disease were ambivalent toward pregnancy, had high levels of depression, had difficulties in recognizing physical and psychological changes, and had difficulties in imagining the child. These are considered risk factors that could negatively affect the postnatal mother-infant relationship. These results focus on the importance of early multidisciplinary interventions that can support expectant women when they show signs of relationship difficulties with their infants prior to his/her birth.

Fabrication of long tubular parts made of tungsten-heavy alloys by inductive bonding of multiple tubes

The structural integrity of tungsten-heavy alloy (THA) powder compacts, shaped into long tubular parts with a high length-to-diameter ratio, are difficult to handle and break easily owing to the low strength of powder compacts and heaviness of THA powders. Furthermore, slumping that occurs during liquid-phase sintering may induce a dimensional distortion and degrade their mechanical properties. To overcome these difficulties, a method for fabricating long tubular parts by inductively bonding multiple unit tubes locally is proposed and characterized. Customized long tubular parts are fabricated by stacking straight and tapered unit tubes in a vacuum chamber and inductively bonding them to produce straight or tapered tubular parts. Bond strength essentially equals the strength of individual unit tubes. Inductive-bonding performance was estimated and optimized with respect to various process factors, including the environmental atmosphere, temperature, joining pressure, and rotational positioning of stacked tubes. The manufacturing process, amenable to industrial application, is well characterized, and its feasibility is demonstrated by a product free of gravity induced distortion and excellent bond quality, assessed in terms of microstructure and mechanical properties.

Dentists' performance in dentin-composite resin bonding before and after hands-on course learning

The restoration longevity depends on a high dentin-composite bond quality. This study investigated learning outcomes when using etch-and-rinse and self-etch adhesives among general practitioners in a hands-on bonding test course. We recruited 30 general practitioners to perform shear bond strength (SBS) tests using five adhesives: one Peak® Universal Bond (PUB) etch-and-rinse and four Futurabond DC, Single Bond universal (SBU), Versa Optibond (VOB), and Tetric-N Bond Self-Etch (TNS) self-etch adhesives. SBS tests were conducted at pre-demonstration (pre-demo), post-demonstration (post-demo), and 24-h storage (delayed bonding) stages. SBS data were analyzed with paired Student's t-tests. We defined 17MPa as "qualified bond strength (QBS)". The percentages of samples with SBS achieving QBS were analyzed using Mantel-Haenszel chi-square tests. The fracture surfaces of the samples were examined by scanning electron microscopy (SEM). Using PUB caused no significant differences in SBS between pre- and post-demo samples, whereas the SBS of the two self-etch adhesives (SBU and VOB) improved in post-demo samples (p<0.05). SBU showed the highest percentage of samples with SBS achieving QBS in all three groups (pre-demo=70%, post-demo=83%, and delayed bonding=76.5%). The QBS percentages of VOB and TNS notably improved from 0% (pre-demo) to 71.4% and 23.5% (post-demo), respectively. SEM indicated bubble-like defects at the dentin-resin interfaces in cases of low SBS. Bonding performance is both operator- and product-dependent. The continuing education hands-on course does help dentists to improve the bond strength especially when the self-etch system is used.

Paraphilias and Violence in the couple. An integrative approach

The systemic therapy has given great attention to the violent dynamics of couples, but has rarely connected the different forms of violence with the Paraphilic Disorder. The phenomenology of the Paraphilic Disorder tells us the violence is a certain and fixed data instead. The common perception about Paraphilic Disorder is based on the image of a solitary individual coercively chained to rigid and stereotypical sexual fantasies. Clinical practice, on the other hand, tells us that, in most cases of Paraphilic Disorder, the patient forms a fixed or long-lasting couple and therefore shares and elaborates the perverse ritual with a partner. So it’s necessary view four levels to understand the evil, the hatred, that leads to dehumanize the partner: genetic baggage, motivational systems organization, relational pattern and emerging qualities of bonds. Generally the systemic approach has given great attention to the two later points. In particular, in this paper the author supports the importance of understanding and healing the “third world” that every couple co-create: the couple's absolute (Caille, 2007). In this paper the couple's absolute are called the “We”, meaning a collective mental dimension that contains mythological, cognitive and somatic aspects that generate a unique identity for each couple. If the therapist understand the “We”, can grasp the real meaning of the violent acts in the couple and this is a central point of a real therapeutic change.