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Polyurethane concrete (PUC), as a new type of steel bridge deck paving material, the bond-slip pattern at the interface with the steel plate is not yet clear. In this study, the mechanical properties of the PUC and steel plate interface under the coupled action of temperature, normal force and tangential force were explored through shear tests and numerical simulations. An analytical model for bond-slip at the PUC/steel plate interface and a predictive model for the shear strength of the PUC/steel plate interface were developed.

The new shear test device designed in this paper overcomes the defect that the traditional oblique shear test cannot test the interface shear performance under the condition of fixed normal force. The universal testing machine (UTM) test machine was used to adjust the test temperature conditions. Combined with the results of the bond-slip test, the finite element simulation of the interface is completed by using the COHENSIVE unit to analyze the local stress distribution characteristics of the interface. The use of variance-based uncertainty analysis guaranteed the validity of the simulation.

The shear strength (τ_f) at the PUC-plate interface was negatively correlated with temperature while it was positively correlated with normal stress. The effect of temperature on the shear properties was more significant than that of normal stress. The slip corresponding to the maximum shear (D₁) positively correlates with both temperature and normal stress. The interfacial shear ductility improves with increasing temperature.

Based on the PUC bond-slip measured curves, the relationship between bond stress and slip at different stages was analyzed, and the bond-slip analytical model at different stages was established; the model was defined by key parameters such as elastic ultimate shear stress τ₀, peak stress τ_f and interface fracture energy G_f.

The purpose of this paper is to study the bonding properties of Larch with water‐based polymer isocynate (WPI) adhesive to provide theoretical instruction for practical production of Larch glued laminated timber with WPI adhesive.

This study adopted Japanese JIS K6806 standard to test bonding properties of Larch with WPI adhesive. Scanning electron microscope was used to observe morphography of Larch surface. Micro photos were adopted to show the penetration of WPI adhesive on the radial and tangential surfaces of Larch.

There was significant difference in bonding strength between Larch radial and tangential glue‐blocks glued with WPI adhesive. Dry compressing shear strength of Larch radial glue‐block bonded with WPI adhesive was 1.41 times that of Larch tangential glue‐block bonded with WPI adhesive in normal conditions. Wood failure showed that the difference between Larch radial and tangential glue‐block was caused by wood structure of Larch itself.

The research conclusion that the dry compressing shear strength of Larch radial glue‐block bonded with WPI adhesive was bigger than that of Larch tangential glue‐block bonded in normal conditions. These would be changed if other adhesives were adopted to glue Larch wood.

The conclusion developed in this study provided a practical production instruction for Larch glued laminated timber with WPI adhesive. In order to obtain better bonding properties during the production of Larch glued laminated wood, Larch wood should be sawn into radial boards rather than tangential boards in order to obtain maximum bonding strength of Larch wood.

The paper shows that there was significant difference in bonding strength between Larch radial and tangential glue‐bonded blocks with WPI adhesive. Dry compressing shear strength of Larch radial glue‐block bonded with WPI adhesive was 1.41 times that of Larch tangential glue‐block bonded with WPI adhesive in normal conditions.

This study aims to develop a bimodal nano-silver paste with improved mechanical property and reliability. Silicon carbide (SiC) particles coated with Ag were introduced in nano-silver paste to improve bonding strength between SiC and Ag particles and enhance high-temperature stability of bimodal nano-silver paste. The effect of sintering parameters such as sintering temperature, sintering time and the proportion of SiC particles on mechanical property and reliability of sintered bimodal nano-silver structure were investigated.

Sandwich structures consist of dummy chips and copper substrates with nickel and silver coating bonded by nano-silver paste were designed for shear testing. Shear strength testing was conducted to study the influence of SiC particles proportions on the mechanical property of sintered nano-silver joints. The reliability of the bimodal nano-silver paste was evaluated experimentally by means of shear test for samples subjected to thermal aging test at 150°C and humidity and temperature testing at 85°C and 85 per cent RH, respectively.

Shear strength was enhanced obviously with the increase of sintering temperature and sintering time. The maximum shear strength was achieved for nano-silver paste sintered at 260°C for 10 min. There was a negative correlation between the proportion of SiC particles and shear strength. After thermal aging testing and humidity and temperature testing for 240 h, the shear strength decreased a little. High-temperature stability and high-hydrothermal stability were improved by the addition of SiC particles.

Submicron-scale SiC particles coated with Ag were used as alternative materials to replace part of nano-silver particles to prepare bimodal nano-silver paste due to its high thermal conductivity and excellent mechanical property.

To use distinct element simulation (PFC2D) to investigate the relationships between microparameters and macroproperties of the specimens that are modeled by bonded particles. To determine quantitative relationships between particle level parameters and mechanical properties of the specimens.

A combined theoretical and numerical approach is used to achieve the objectives. First, theoretical formulations are proposed for the relationships between microparameters and macroproperties. Then numerical simulations are conducted to quantify the relationships.

The Young's modulus is mainly determined by particle contact modulus and affected by particle stiffness ratio and slightly affected by particle size. The Poisson's ratio is mainly determined by particle stiffness ratio and slightly affected by particle size. The compressive strength can be scaled by either the bond shear strength or the bond normal strength depending on the ratio of the two quantities.

The quantitative relationships between microparameters and macroproperties for parallel‐bonded PFC2D specimens are empirical in nature. Some modifications may be needed to model a specific material. The effects of the particle distribution and bond strength distribution of a PFC2D specimen are very important aspects that deserve further investigation.

The results will provide guidance for people who use distinct element method, especially the PFC2D, to model brittle materials such as rocks and ceramics.

This paper offers some new quantitative relationships between microparameters and macroproperties of a synthetic specimen created using bonded particle model.

This study aims to investigate and compare the interfacial bond characteristics between fire-damaged normal concrete substrate and ultra-high-performance fiber-reinforced concrete (UHPFRC) as a repair material.

First, fire-damaged normal concrete was prepared. Then, with a cast surface, the substrate was subjected to different surface moisture conditions. Three types of moisture conditions were set, namely, air dry, saturated surface dry (SSD) and wet. Slant shear and splitting cylinder tests were conducted to determine the interfacial bond strength of the composite.

In general, results indicate that surface moisture conditions significantly influence bond strength. The substrate under SSD condition exhibited the highest bond strength. The findings suggest that UHPFRC is a promising material for the repair and reuse of fire-damaged concrete structures.

This study compares the bond strength between fire-damaged normal concrete and UHPRC.

It is well known that stress singularity may exist at the edges of a bonded bi‐material interface due to the discontinuity of material properties. This stress singularity causes difficulty in accurately determining the bi‐material interface bonding strength. This paper aims to present a new design of specimen geometry to eliminate the stress singularity and present an experimental procedure to more accurately determine the bonding strength of the bi‐material interface.

The design is based on an asymptotic analysis of the stress field near the free edge of bi‐material interface. The critical bonding angle, which delineates the singular and non‐singular stress field near the free edge, is determined.

With the new designed specimen and a special iterative calculation algorithm, the interface bonding strength envelope of an epoxy‐aluminum interface was experimentally determined.

This new design of specimen, experimental procedure and iterative algorithm may be applied to obtain more reasonable and accurate bonding strength data for a wide range of bi‐material interfaces.

This paper deals with experimental and numerical investigations of the composite behaviour within concrete-filled tubular columns with embedded massive steel core (CFTES columns). As the inner profile provides the main load-bearing capacity, the load introduction and transfer is of particular interest for the structural detailing of CFTES columns. Currently, no specific design regulations are available – neither for room temperature nor fire design. The presented investigations provide a basis for design recommendations and numerical approaches on reliable shear stresses.

Three series of push-out tests at room temperature and high temperatures are analysed in terms of ultimate shear strength, bond strength and shear strength-displacement-curve shape. The test parameters involve the steel core diameter and concrete cover, applying normal strength steel and concrete. Furthermore, a three-dimensional finite element model of the push-out tests is set up in Abaqus. The model implies temperature-dependent contact properties derived from the experimental tests using the cohesive behaviour method.

The test data reveal a distinctive reduction in both ultimate shear and bond strength for high temperatures. For high temperatures, the thermal expansion coefficients dominate the composite behaviour. Using the 3D numerical model and applying a temperature-dependent joint stiffness, maximum shear stress criterion and damage evolution, the observed composite behaviour can be described in a realistic manner.

The presented experimental investigations are unique, both concerning the investigated column type and performing push-out tests at high temperatures. For the first time, a temperature-dependent reduction of capable shear stresses is identified, which is crucial for the design of structural components.

The effects of failure mode and strain conditions of CFRP, concrete and stirrups on the shear capacity of reinforced beams bonded by geopolymer and epoxy are studied. In addition, a prediction model of the ultimate bearing capacity of CFRP-shear-strengthened beams is proposed, which considers adhesive performance parameters adhesive performance parameter ßE and FRP width parameter ßw.

This paper presents an experimental study on ultimate bearing capacity of CFRP-shear-strengthened pre-cracked beams with geopolymer and epoxy resin, which considers parameters such as impregnated adhesives types and CFRP-strengthened scheme.

The failure modes of CFRP-strengthened beams bonded by geopolymer are the combination of the CFRP-concrete interface substrate failure and fracture failure of CFRP, and that of epoxy is the local substrate failures with small area. The ultimate load of CFRP-strengthened beams is directly affected by the failure modes. The ultimate bearing capacity of CFRP-strengthened beams with geopolymer is 91.4% of that of epoxy resin. Compared with ultimate bearing capacity of CFRP-strengthened beams with U-shaped, that of complete-wrapping increases by 2.5%. Moreover, the stirrup peak strain is reduced by more than 30% in CFRP-strengthened beams bonded with geopolymer and epoxy resin in comparison with the unstrengthened beam. The existing prediction model cannot accurately predict the CFRP shear capacity contribution of strengthened beams with different CFRP-strengthened schemes and adhesive properties. The estimated results are much lower than the test data, and the deviation is much larger than 20%.

Geopolymer alternative to epoxy as an adhesive is feasible and effective for CFRP reinforcement. Furthermore, the accuracy is improved by introducing parameters about adhesive properties based on the existing prediction model. The estimated results are in excellent agreement with the test data, and the deviation is controlled within −12.80%, and the model is suitable for predicting the shear capacity of FRP-strengthened beams with ßf = 90° in shear capacity database.

In a plastic BGA package, the glass transition temperature of 170‐215°C for bismaleimide triazine (BT) substrate puts an upper ceiling to the usable wire bond temperature. To compensate for the limitation in thermal energy, high frequency thermosonic bonding was proposed and successfully demonstrated for plastic BGA wire bonding. Design of experiment (DOE) and response surface methods (RSM) for process optimisation were used; bonded areas were also analysed using scanning electron microscope (SEM). Of the four major bonding parameters were investigated, ultrasonic power and bond force appeared to be the most important control factor for wire pulls and ball shear force optimisation. The results show that bonding at low temperature is viable with the use of high frequency transducer wire bonder.

Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h).

The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on.

It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad.

In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation.