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This paper aims to present a viscoplastic constitutive model of Sn‐Pb solder taking into account the evolution of microstructure and damage growth in the material.

The microstructure evolution is represented by a parameter describing the coarsening of the phase size, and its resulting evolution equation is established from previous experimental data. The damage evolution is derived from the theory of damage mechanics within the framework of irreversible thermodynamics. Both a phase‐size parameter and a damage variable are included in the constitutive model.

The model is capable of simulating the effects of Sn‐Pb solder microstructure on mechanical behaviour for both bulk material and miniature specimens under monotonic tensile loading. It was found that the expected failure location determined using the phase‐size criterion is identical to that using the damage criterion, but differs from that determined using the von Mises stress criterion.

Microstructure and damage evolution are modelled for Sn‐Pb solder. Some simulation results are compared with the experimental data to provide the necessary validation of the damage/microstructure‐coupled constitutive model.

The purpose of this paper is to present results of laboratory testing work on causes of a service failure/damage to an aircraft turbojet's gas‐turbine blade made of the EI 867‐WD alloy.

The tests comprised comparing the microstructure of a service‐damaged blade with microstructures of specimens drawn from a similar all‐new blade, both subjected to temperatures of different values for different annealing times.

Findings based on the comparison of experimentally gained results of microstructure examination of both the gas‐turbine blades were: the change in the microstructure of a damaged blade results from the growth and cuboidal‐to‐lamellar change of shape of the reinforcing phase γ′ (Ni₃Al); and the size and shape of this phase are comparable to those of the phase γ′ of a new blade subjected to annealing at temperature exceeding 1,223 K for 1 h. The results gained allowed for drawing the conclusion that the damaged turbine blade was operated in the exhaust‐gas temperature exceeding the maximum permissible value of 1,013 K for approximately 1 h in the course of an air mission.

The comparison‐oriented experimental testing work was carried out on a new blade manufactured in the way and from material identical to those of the damaged blade. The applied methodology enables us to gain qualitative results of investigating into the causes of a failure/damage to a gas‐turbine blade.

The presented methodology of identifying (origin‐finding of) a service‐induced damage to a gas‐turbine blade proves helpful in the case of an engine failure, when information on the operating conditions thereof is insufficient.

The paper is an original work by the authors. To the best of their knowledge, the issue has not been found in the literature, approached in this particular way. It has been based on research work on air accidents due to the service‐induced failures/damages to gas‐turbine blades in aircraft turbojet engines.

This paper aims to describe and document the application of commonly utilized solder joint failure analysis techniques to lead‐free solder joints.

Traditional failure analysis techniques, including visual inspection, X‐ray radiography, mechanical strength testing, dye and pry, metallography, microscopy and photomicrography, are reviewed. These techniques are demonstrated as applied to lead‐free and tin lead solder joints. Common failure modes observed in lead‐free and tin lead solder joints are described and compared.

It is shown that the traditional failure analysis techniques previously utilized for tin lead solder joints are widely applicable to the analysis of lead‐free solder joints. The changes required to effectively apply these techniques to the analysis of lead‐free solder joints are described.

This paper will be instrumental to the process, quality, reliability and failure analysis engineering disciplines in furthering understanding of the application of failure analysis techniques of both tin lead and lead‐free solder joints.

This study aims to analyze the factors, evaluation techniques of the durability of existing railway engineering.

China has built a railway network of over 150,000 km. Ensuring the safety of the existing railway engineering is of great significance for maintaining normal railway operation order. However, railway engineering is a strip structure that crosses multiple complex environments. And railway engineering will withstand high-frequency impact loads from trains. The above factors have led to differences in the deterioration characteristics and maintenance strategies of railway engineering compared to conventional concrete structures. Therefore, it is very important to analyze the key factors that affect the durability of railway structures and propose technologies for durability evaluation.

The factors that affect the durability and reliability of railway engineering are mainly divided into three categories: material factors, environmental factors and load factors. Among them, material factors also include influencing factors, such as raw materials, mix proportions and so on. Environmental factors vary depending on the service environment of railway engineering, and the durability and deterioration of concrete have different failure mechanisms. Load factors include static load and train dynamic load. The on-site rapid detection methods for five common diseases in railway engineering are also proposed in this paper. These methods can quickly evaluate the durability of existing railway engineering concrete.

The research can provide some new evaluation techniques and methods for the durability of existing railway engineering.

As in real applications several alternating current (AC) currents may be injected to the electronic devices, this study aims to analyze their effects on the lifetime of the solder joints and, consequently, shed the light on these effects at the design phase for other researchers to consider.

In this paper, the authors investigated on current waveform shapes on the performance and reliability of the solder joints in electronic package. Three common and extensively used current shapes in several simulations and experiments were selected to study their effects on the solder joint performance.

The results demonstrate a sever thermal swing and stress fluctuation in the solder joint induced in the case of triangle current type because the critical states lack any relaxation time. In fact, the stress intensification in the solder under application of the triangle current type has been shown to contribute to increasing brittle intermetallic compounds. An accelerated increase of on-state voltage of power semiconductor was also observed in under application of the triangle current type.

The originality of this paper is confirmed.

The multi-scale numerical simulation method, able to represent the complexity of the random structures and capture phase degradation, is an effective way to investigate the long-term behavior of concrete in service and bridges the gap between research on the material and on the structural level. However, the combined chemical-physical deterioration mechanisms of concrete remain a challenging task. The purpose of this paper is to investigate the degradation mechanism of concrete at the waterline in cold regions induced by combined calcium leaching and frost damage.

With the help of the NIST’s three-dimensional (3D) hydration model and the random aggregate model, realistic 3D representative volume elements (RVEs) of concrete at the micro-, the meso-, and the macro-scales can be reconstructed. The boundary problem method is introduced to compute the homogenized mechanical properties for both sound and damaged RVEs. According to the damage characteristics, the staggering method including a random dissolution model and a thermo-mechanical coupling model is developed to simulate the synergy deterioration effects of interacted calcium leaching and frost attacks. The coupled damage procedure for the frost damage process is based on the hydraulic pressure theory and the ice lens growth theory considering the relationship between the frozen temperature and the radius of the capillary pore. Finally, regarding calcium leaching as the leading role in actual engineering, the numerical methodology for combined leaching and frost damage on concrete property is proposed using a successive multi-scale method.

On the basis of available experimental data, this methodology is employed to explore the deterioration process. The results agree with the experimental ones to some extent, chemical leaching leads to the nucleation of some micro-cracks (i.e. damage), and consequently, to the decrease of the frost resistance.

It is demonstrated that the multi-scale numerical methodology can capture potential aging and deterioration evolution processes, and can give an insight into the macroscopic property degradation of concrete under long-term aggressive conditions.

The purpose of this paper is to describe finite element modelling for fracture and fatigue behaviour of zirconia toughened alumina microstructures.

A two‐dimensional finite element model is developed with an actual Al₂O₃‐10 vol% ZrO₂ microstructure. A bilinear, time‐independent cohesive zone law is implemented for describing fracture behaviour of grain boundaries. Simulation conditions are similar to those found at contact between a head and a cup of hip prosthesis. Residual stresses arisen from the mismatch of thermal coefficient between grains are determined. Then, effects of a micro‐void and contact stress magnitude are investigated with models containing residual stresses. For the purpose of simulating fatigue behaviour, cyclic loadings are applied to the models.

Results show that crack density is gradually increased with increasing magnitude of contact stress or number of fatigue cycles. It is also identified that a micro‐void brings about the increase of crack density rate.

This paper is the first step for predicting the lifetime of ceramic implants. The social implications would appear in the next few years about health issues.

This proposed finite element method allows describing fracture and fatigue behaviours of alumina‐zirconia microstructures for hip prosthesis, provided that a microstructure image is available.

The purpose of this study is to investigate the effect of standard fire on the strength and microstructure properties of concrete with different strength grades.

Different strength grades of concrete used for the investigation are M20, M30, M40 and M50. An electrical bogie hearth furnace was developed to simulate the International Standards Organization 834 standard fire curve.Concrete samples were subjected to high temperatures of 925, 1,029, 1,090 and 1,133°C for the duration of 1, 2, 3 and 4 h, respectively, as per standard fire curve. Compressive strength, tensile strength, thermal crack pattern and spalling of heated concrete specimens were evaluated by experimental investigation. Scanning electron microscopy and thermo-gravimetric analysis were performed to investigate the microstructure properties of heated concrete specimens.

Test results indicated reduction in the strength and changes in the microstructure properties of concrete exposed to elevated temperature. The degree of weight and the strength loss were found to be higher for concrete with higher grades. An empirical relation is proposed to determine the residual strength of concrete with different strength grade using regression analysis.

Results of this research will be useful for the design engineers to understand the behavior of concrete exposed to elevated temperature as per standard fire.

When concrete is exposed to elevated temperature, its internal microstructure changes, thereby strength and durability of concrete deteriorates. The performance of concrete with different strength grade exposed to standard fire is well understood. This research’s findings will be useful for the designers to understand more about fire resistance of concrete. A simple relationship is proposed to determine the residual strength of concrete exposed to various durations of heating.

The main purpose of this study was to evaluate the mechanical behaviour of layered fibrous carbon-fibre reinforced plastic (CFRP) under complex low-speed bending and impact loads and subsequent cyclic tensile loads.

A comprehensive approach was adopted to study the damage accumulation processes using state-of-the-art testing and diagnostic equipment. In the course of the study, a microstructure analysis of damages caused by a transverse impact and cyclic tension was performed.

A dependence of residual fatigue life of the studied composite material on the intensity of the preliminary impact bending was established. Temperature field distribution fields on the surface of the sample during tests were shown. Data on damage accumulation processes were presented, which were obtained during the registration of acoustic emission signals.

A connection was established between changes of registered acoustic response signals and thermal imaging camera data, which was supported by the results of an experimental study. The results of the comprehensive approach showed a qualitative correlation.

According to the microstructural characteristics of composite ceramic, the strain field distribution regularity of triangular symmetrical composite eutectic is obtained from the stress field distribution regularity of three-phase element in composite ceramic. In allusion to the damage of composite eutectic, it is introduced as a variable in this paper with the aim to determine the strain field distribution regularity of triangular symmetrical composite eutectic with damage behavior.

On the basis of the relationship between strain field and fiber inclusions volume fraction, the strain field of composite eutectic is analyzed.

The strain field of composite ceramic is distinctly dependent on the fiber inclusions volume fraction, fiber diameter and damage behavior of composite eutectic by quantitative analysis. The strain in matrix parallel to eutectic is the maximum linear strain and the main factor for the damage and fracture of eutectics.

The foundation of the strength research of composite eutectic is laid.