Thermal Fatigue Life Research Articles

Optimal design of radial tire section layout based on thermal fatigue life improving

The design of tire fatigue life was optimized by combining approximate model and finite element simulation, and compared with the tire endurance test results. The design variables are selected through sensitivity analysis of materials in various regions of the tire, and the thermal fatigue life of the tire is used as the objective function, and the approximate relationship between the design variables and the objective function is fitted based on the approximate model method, and the approximate model is optimized using genetic algorithm to find the optimal solution. The fatigue life of the tire is improved by about 25 %.

Thermal stress simulation and fatigue life of commercial vehicle disk brakes under emergency braking conditions

Commercial vehicle disk brakes operate at a high-temperature and in a heavy-load environment within the braking system. The primary cause of failure is the cracking of the brake disk. In order to study its fatigue damage and service life, a finite element model of disk brake fatigue life was established, and thermal stress coupling simulation analysis was carried out from a practical problem. Based on the temperature and stress fields of the brake disk under emergency braking conditions obtained from the simulation results, the effects of vehicle load, initial speed, temperature, and other factors on brake fatigue life are explored. The fatigue life of the hazardous node can be calculated using the Manson–Coffin model, and then the strain–life (ɛ–N) curve of the material can be fit at high temperature. The fatigue life of brake disks was predicted using the fatigue analysis software FE-SAFE and verified by testing. The results showed that the maximum stress on the surface of the disk brake was the same as the area of the minimum fatigue life, accurately analyzing the fatigue life of the region and predicting the location of fatigue cracks. The results of the research can provide a reference for the design of disk brake engineering and fatigue failure.

Thermal fatigue life prediction method for die casting mold steel based on the cooling cycle

Thermal fatigue life prediction method for die casting mold steel based on the cooling cycle

Experiment and numerical simulation study of thermal fatigue of an aluminum alloy piston

AbstractIn this study, a magneto‐thermo‐structural coupling finite element method was proposed to calculate the electromagnetic field, temperature field, stress field, and strain field of an aluminum alloy piston during thermal shock process. The computed temperature results at the measurement points of T3 and T4 agree well with the measured data. The concept of tensile strain energy density was proposed as a thermal fatigue damage parameter, and the thermal fatigue life of the piston was predicted on the basis of the calculated results by magneto‐thermo‐structural coupling analysis and tensile strain energy density‐life equation; the discrepancy between the predicted life and the experimental one is 16%. The thermal fatigue failure mechanism of the piston was also clarified. High cyclic stresses occur on the edge of Si due to the difference in thermal expansion coefficient of Al and Si; micro cracks first originate on the edge of Si, then grow through combining other micro cracks, and eventually form macro cracks.

Temperature Cycle Reliability Analysis of an FBAR Filter-Bonded Ceramic Package.

On the background that the operating frequency of electronic devices tends to the radio frequency (RF) segment, a film bulk acoustic resonator (FBAR) filter is widely used in communication and military fields because of its advantages of high upper frequency, ample power capacity, small size, and low cost. However, the complex and harsh working environment puts higher requirements for packaging FBAR filters. Based on the Anand constitutive equation, the stress-strain response of the bonded ceramic package was studied by the finite element method for the FBAR filter-bonded ceramic package, and the thermal fatigue life of the device was predicted. We developed solder models with various spillage morphologies based on the random generation technique to examine the impact of spillage on device temperature reliability. The following are the primary conclusions: (1) Solder undergoes periodic deformation, stress, and strain changes throughout the cycle. (2) The corner of the contact surface between the chip and the solder layer has the largest stress at the end of the cycle, measuring 19.377 MPa. (3) The Engelmaier model predicts that the gadget will have a thermal fatigue life of 1928.67 h. (4) Expanding the layered solder area caused by any solder overflow mode may shorten the device's thermal fatigue life. The thermal fatigue life of a completely spilled solder is higher than that of a partially spilled solder.

Conventional shot peening treatment effects on thermal fatigue crack growth and failure mechanisms of a solid solution alloy

This study presents the effects of conventional shot peening as a surface post-treatment method on the fatigue crack growth behavior and failure mechanism of a solid solution alloy used in the flat seal component under thermal fatigue conditions. The study employs a combination of experimental tests and finite element simulations to evaluate the effect of shot peening on thermal fatigue crack growth behavior. The corrected J-integral and Paris model are used to calculate the stress intensity factor and predict the thermal fatigue crack growth behavior, respectively. Additionally, the ZENCRACK method is employed to predict thermal fatigue life. The results indicate that shot peening induces compressive residual stress, leading to a decreased distribution of thermal stress, particularly along the crack propagation path. The simulated fatigue life curve obtained by ZENCRACK demonstrated a good agreement between the simulated and experimental crack growth results. The incorporation of shot peening caused a significant reduction in the rate of thermal fatigue crack growth, and the simulated stress intensity factor analysis revealed an increase during the heating stage. Consequently, the thermal fatigue crack propagated during the heating-up process. SEM evaluation reveals that the shot peening post-treatment impacts both thermal fatigue crack initiation and propagation. Furthermore, the failure mode of shot-peened specimens involves inter- and trans-granular cracking, while non-shot-peened specimens exhibit trans-granular cracking.

Construction of a new n-body potential and multi-scale investigations of the direct alloying behaviors for immiscible W/Cu system

Achieving direct alloying at the tungsten/copper (W/Cu) interface is crucial for the fabrication of laminar metal matrix composite (LMMC) plasma-facing components (PFCs) of fusion reactors based on immiscible W/Cu systems. Our previous work has accomplished direct alloying between immiscible W and Cu, forming a diffusion layer with a thickness of approximately 22–32 nm at the interface. The performance of the interface directly affects the lifetime and reliability of W/Cu LMMC. Multi-scale calculations are designed since some interface properties cannot be directly measured or observed experimentally in real-time and in situ. Firstly, a new potential is constructed to overcome the limitations that the existing W/Cu potential cannot accurately describe the W/Cu alloying process. Secondly, molecular dynamics (MD) simulations use the new potential to study interfacial properties and calculate the diffusion depth at the W/Cu interface. Lastly, combining MD, FEM, and image visualization techniques, a multi-scale method of the crack propagation rate at the W/Cu interface is used to predict the thermal fatigue life of W/Cu LMMC PFCs prepared by nano-active structure-induced alloying. Our simulation results agree with experimental values and literature results, demonstrating the reliability of the new W/Cu potential and the accuracy of our designed multi-scale method. Directly alloyed W/Cu LMMCs have the potential to be utilized in fusion reactors.

Effect of thermal cycling on the strain and stress distribution of TSVs and solder bumps in stacked package structure

Aerospace exploration requires electronic devices to withstand the test of extreme environments, and it is of great significance to study the reliability of packaged devices at extreme temperatures. In this paper, the Anand model is used to describe the mechanical constitutive behavior of Sn-3.0Ag-0.5Cu (SAC305) solder and through-silicon via (TSV) in a 3D package structure, and the thermal cycling behavior of controlled collapse chip connection (C4) bumps and TSV arrays under thermal cycling from -100 to 120 °C is analyzed. The thermal fatigue life of C4 bumps and TSVs was evaluated according to the modified Coffin-Manson model. The results show that the maximum stress is 50.57 MPa at the contact interface between the C4 bump and the chip, which is caused by local thermal mismatch. The maximum equivalent plastic strain of the key bump is 1.6 × 10−2 and its fatigue life under extreme temperature thermal cycling conditions is about 1366 cycles. The maximum equivalent plastic strain of the TSV array is 2.8 × 10−2, located at the corner of the peripheral TSV, which is the most dangerous position in the TSV array, and its thermal fatigue life is about 1.9 × 106 cycles.

Numerical evaluation of the mechanical response of Sn-Ag-Cu lead-free solders of various silver contents

PurposeThere are several lead-free solder alloys available in the industry. Over the years, the most favorable solder composition of tin-silver-copper (Sn-Ag-Cu [SAC]) has been vastly used and accepted for joining the electronic components. It is strongly believed that the silver (Ag) content has a significant impact on the solder mechanical behavior and thus solder thermal reliability performance. This paper aims to assess the mechanical response, i.e. creep response, of the SAC solder alloys with various Ag contents.Design/methodology/approachA three-dimensional nonlinear finite element simulation is used to investigate the thermal cyclic behavior of several SAC solder alloys with various silver percentages, including 1%, 2%, 3% and 4%. The mechanical properties of the unleaded interconnects with various Ag amounts are collected from reliable literature resources and used in the analysis accordingly. Furthermore, the solder creep behavior is examined using the two famous creep laws, namely, Garofalo’s and Anand’s models.FindingsThe nonlinear computational analysis results showed that the silver content has a great influence on the solder behavior as well as on thermal fatigue life expectancy. Specifically, solders with relatively high Ag content are expected to have lower plastic deformations and strains and thus better fatigue performance due to their higher strengths and failure resistance characteristics. However, such solders would have contrary fatigue performance in drop and shock environments and the low-Ag content solders are presumed to perform significantly better because of their higher ductility.Originality/valueGenerally, this research recommends the use of SAC solder interconnects of high silver contents, e.g. 3% and 4%, for designing electronic assemblies continuously exposed to thermal loadings and solders with relatively low Ag-content, i.e. 1% and 2%, for electronic packages under impact and shock loadings.

Influences of induced heating-healing on fracture properties and life extension of asphalt mixtures: Experimental investigations

In recent years, researchers have concentrated on identifying the effectiveness of induced healing techniques and increasing the healing capacity of asphalt materials. However, the impact of the induced healing method on extending pavement life or the behavior of the pavement in terms of cracking progression has not been evaluated. The main objective of this study is to develop a methodology to evaluate the impact of induced healing on fracture characteristics and life extension of asphalt mixtures. Semi-circular bending (SCB) tests were conducted at both 25 °C and −20 °C. From the SCB test results, fracture-related parameters such as peak load, critical stress intensity factor, strain energy, J-integral, fracture energy, and stiffness were determined. The SCB tests were carried out under cyclic cracking-healing scenarios to assess the effectiveness of the healing process. To quantify the healing efficiency, fracture-related parameters and corresponding healing indices (HI) were measured at each damage cycle. Additionally, service life extensions were calculated based on the analysis of fatigue and thermal cracking resistance. Finally, the HI obtained through other fracture-related parameters were used as a response factor to evaluate the statistical significance of each fracture parameter. The results show that for unaged asphalt mixtures, service life extensions for fatigue and thermal cracking resistance were 3.61 and 3.46 times the initial pavement life, respectively. In contrast, for specimens that experienced 20 years of aging after construction, the corresponding values were 1.50 and 2.23. This suggests that while increasing levels of aging reduce the effectiveness of the induced healing process, the pavement life can still be extended by using the induced healing method. Furthermore, a significant variation was observed in the HI obtained from different fracture-related parameters for asphalt mixtures at different aging levels. This suggests that using the ultimate strength of specimens to determine HI may present conservative results for aged asphalt mixtures since it does not explain the cracking features of the asphalt mixture at intermediate temperatures. The proposed fracture-based method can represent the interactions of cracking and time-dependent behaviors of materials, allowing for the combined effects of the healing process on fatigue and thermal fatigue life extensions to be addressed.

Interfacial thermal damage and fatigue between auxetic honeycomb sandwich and underneath substrate

A general model to evaluate the interfacial thermal damage and predict the fatigue life of the auxetic honeycomb-substrate structure (H-SS) is built. To improve the accuracy, all material parameters in the model are temperature-dependent. The transient temperature field and the associated thermal stresses associated with the temperature changes in the structure are determined by the finite difference method. The interfacial thermal stress intensity factor is employed to characterize the stress concentration behavior. Based on the stress field and the stress concentrations at the interface, interfacial thermal damage evolution and fatigue life prediction of the structure are made. The results show that the auxetic property can significantly enhance the fatigue life of the structure. The fatigue life will be undervalued when the effect of temperature-dependent material properties (TDMPs) is neglected. Furthermore, the influence of TDMPs on the fatigue life of the structure will increase as the absolute value of the internal cell angle increases. This paper provides a comprehensive assessment of the thermal damage and fatigue life of auxetic H-SSs and can serve as a solid theoretical foundation for future applications of related structures in extreme temperature environments.

Nonlinear finite element simulations on the mechanical response of the isothermally aged lead-free solders

The mechanical response, material properties, and mechanical failures of the lead-free solder interconnects continuously evolves and changes due to the isothermal ageing process and during thermal cycling. Therefore, it is very important to include such evolution behavior in the finite element-based evaluations of the solder thermal fatigue life analysis. The current article aims to investigate the effect of the pre-isothermal ageing on the mechanical response of the thermally cycled SAC305 lead-free interconnects utilizing finite element analysis and literature-based material parameters. Additionally, this article explores the solder creep response using two common constitutive laws, Anand and Garofalo models. The simulation results showed that the solder mechanical behavior due to thermal cycling is strongly driven by the ageing process especially for shorter time of ageing. Nonetheless, this effect becomes less effective for prolonged ageing periods. Moreover, the numerical computations proved that the solder response becomes mainly dominated by secondary creep rather than viscoplasticity when the solders are exposed to longer ageing durations. Finally, a detailed discussion on the effect of the pre-ageing process on solder plastic strains and inelastic strain energy density and hence the thermal fatigue life is presented.

Effect of Heating Power on Ball Grid Array Thermal Shock Reliability for a Fanout Package

Abstract The reliability of Fanout package with a ball grid array (BGA) for microsystem is studied under thermal shock. Different heat source powers are applied to the silicon substrate to imitate the power dissipation induced heat of power devices and the thermal fatigue life of the package are studied using the Anand constitutive model and Darveaux life model. The finite element method simulation results show that the thermal fatigue life is not positively correlated with the heat source power. In a certain power range, the life first increases and then decreases. To explain this abnormal phenomenon, the fatigue analysis of solder balls with different heating power (10–55 W) is carried out. The results show that in the low temperature stage, with the increase of the heat source power, the heat source offsets the low temperature effect to a certain extent, and the stress value of the solder balls decreases. And during the high temperature stage, the stress of the ball is hardly affected. However, with the increase of the heat source power, the thermal deformation of the structure is gradually serious, the effect of offsetting the low temperature effect is reduced, and the thermal fatigue life increases with the increase of the heat source power. The results of the paper can be useful for microsystem package design.

Experimental and numerical investigation of thermal fatigue life in wedge specimens made of Ni-resist D5S cast iron

Thermal fatigue experiments were performed on a single-edge wedge specimen of Ni-resist D5S cast iron to reproduce the conditions to which exhaust manifolds are subjected during service. The leading edge temperature was cycled between 20°C and 850°C, and the temperature distribution on the specimen surface was measured with thermocouples during thermal cycling. Due to the complexity of the loads, a uncoupled thermomechanical computation of the problem was performed using the three-dimensional finite element code ABAQUS to evaluate the temperature, stress and strain distribution over a thermal fatigue specimen. The heat fluxes and forced convection coefficients generated by the thermal fatigue benchmark were optimized in both heating and cooling phases by reverse engineering to reproduce the experimental temperature-time profiles measured by thermocouples on the surface of the specimen. Then, an elastic-viscoplastic tow-layer model was used to simulate the mechanical behavior of the studied material. It was found that the maximum stress value was located in the center of the specimen at the edge of the wedge. This result was confirmed by experimental observations. The crack initiation zone is located in the edge zone and the direction of crack propagation is perpendicular to the edge line toward the thick part of the specimen. The saturation of the main crack propagation near the uniform specimen zone was mainly explained by the rapid decrease of the energy dissipated per cycle.

Mathematical Model of Properties and Experimental Fatigue Investigation at Elevated Temperatures of Functionally Gradient Materials

Fatigue that occurs at elevated temperatures is called thermal fatigue. High temperatures and cycling loads cause thermal fatigue that can cause component failures. In this paper, induced the mathematical models for functionally gradient materials and three models of functionally gradient materials (FGMs) manufactured by permanent casting were tested to predict their thermal fatigue life. FGMs have been tested to determine the effect of fatigue and temperature interactions. FGMs models were of FGM1, FGM2, and FGM3 respectively, with the following volume fractions and gradations: [100%Al-50%Al50%Zn-50%Zn50%Al-100%Zn], [100%Al-30%Zn70%Al-70%Zn30%Al-100%Zn] and [100%Al-70%Zn30%Al-30%Zn70%Al-100%Zn]. The experimental procedure presented the mechanical properties as modulus of elasticity at two levels of temperatures (80 oC, and 160 oC). Through the results of the tensile test at high temperatures, it was noted that the reduction percentage was high in the second type. This was especially for the yield strength value, where the percentage reached 43% at 160 °C. In the second type, the ultimate strength was affected more at 160 °C: the decrease percentage reached 33%, and the elastic modulus at the same temperature fell by 32%. The third type is the least affected at high temperatures, as the percentage of properties decrease at 160 °C reached 16, 17, and 16% for modulus of elasticity, ultimate strength, and yield strength, respectively. Fatigue strength is the most significant among the mechanical properties, where the highest value of the fatigue limit for the third type was experimentally 149.68 MPa. While the lowest value of fatigue strength was the second type, and at the same time, on the contrary, it was less affected at high temperatures, with a rate of 8%, which reached the decrease. The simulation results from the ANSYS program regarding fatigue at high temperatures were acceptable and gave reasonable variation ratios and were very close to the experimental results.

Thermal fatigue behavior of reinforced concrete column used as heater and energy storage

In this study, the damage effects of a new building heating system that activates the reinforced concrete columns (RC) which are the structural elements of the building by thermal cycles were investigated. The research was carried out experimentally on real-time data. The thermal fatigue effect that will occur after the structural RC is exposed to repeated thermal cycles was evaluated with the lateral cyclic loading test. The effect of the applied thermal cycles on the microstructure of the concrete was also tried to be observed. According to the data obtained in this study, in the preferred concrete type and geometry, the mechanical performance of the RC was not adversely affected at preferred operating temperatures and the number of applied thermal cycles. The results obtained are very promising in terms of the applicability of the new system as a preliminary study. In the proposed system, structural elements will be used as heater and energy storage throughout the life of the building. Therefore, it is essential to predict the exact thermal stress and strain values that the RC will be exposed to, and most importantly, the thermal fatigue life of the structural element under different parameters by future work.

Effect of the microstructure of suspension plasma-sprayed thermal barrier coatings on their thermal cycling damage

The suspension plasma spray (SPS) technique has recently attracted attention due to the variety of microstructures achievable using submicron spray particles mixed with a solvent to form a suspension. Thermal barrier coatings (TBCs) with a columnar microstructure can be obtained using SPS. Because of its unique columnar microstructure achieving high strain tolerance, a top coat sprayed using this technique can efficiently suppress thermal cycling damage in SPS–TBCs. However, there are few reports on the effect of microstructure on the damage behavior of SPS–TBCs with a columnar structure. In this study, the effect of the top coat microstructure on the thermal cycling fatigue of SPS–TBCs was investigated. The size of the complex oxide formed on the top coat–bond coat interface and the length of the cracks at the interface (formed as a result of thermal cycling) increase with the column diameter in the top coat of SPS–TBCs. The thermal spray conditions affect the thermal cycling fatigue life of SPS–TBCs. The SPS–TBC with fine columnar structure exhibits superior thermal cycling fatigue life.

Effects of interface cracks on reliability of surface mount technology interconnection in service environment

PurposeSurface mount technology (SMT) is widely used and plays an important role in electronic equipment. The purpose of this paper is to reveal the effects of interface cracks on the fatigue life of SMT solder joint under service load and to provide some valuable reference information for improving service reliability of SMT packages.Design/methodology/approachA 3D geometric model of SMT package is established. The mechanical properties of SMT solder joint under thermal cycling load and random vibration load were solved by 3D finite element analysis. The fatigue life of SMT solder joint under different loads can be calculated by using the modified Coffin–Manson model and high-cycle fatigue model.FindingsThe results revealed that cracks at different locations and propagation directions have different effect on the fatigue life of the SMT solder joint. From the location of the cracks, Crack 1 has the most significant impact on the thermal fatigue life of the solder joint. Under the same thermal cycling conditions, its life has decreased by 46.98%, followed by Crack 2, Crack 4 and Crack 3. On the other hand, under the same random vibration load, Crack 4 has the most significant impact on the solder joint fatigue life, reducing its life by 81.39%, followed by Crack 1, Crack 3 and Crack 2. From the crack propagation direction, with the increase of crack depth, the thermal fatigue life of the SMT solder joint decreases sharply at first and then continues to decline almost linearly. The random vibration fatigue life of the solder joint decreases continuously with the increase of crack depth. From the crack depth of 0.01 mm to 0.05 mm, the random vibration fatigue life decreases by 86.75%. When the crack width increases, the thermal and random vibration fatigue life of the solder joint decreases almost linearly.Originality/valueThis paper investigates the effects of interface cracks on the fatigue life and provides useful information on the reliability of SMT packages.

A new unified creep‐plasticity constitutive model coupled with damage for viscoplastic materials subjected to fatigue loading

AbstractA new unified creep‐plasticity (UCP) constitutive model coupled with damage is proposed for Sn–3.0Ag–0.5Cu (SAC305), one of the most successfully commercialized Pb‐free solders. By calibrating the proposed damage model based on entropy generation, the fatigue issues are elucidated for SAC305 solder at different temperatures and strain rates. After implementing a user‐defined material subroutine, finite element simulations with the proposed UCP‐damage model are capable of predicting the strength deterioration as the macroscopic response in terms of load‐deformation curves. More importantly, the UCP‐damage model reveals the damage accumulation and evolution of viscoplastic materials sensitive to fatigue deformation at different temperatures and strain rates. By comparing the predictions with and without damage, the equivalent plastic strains are obviously different when evaluating the thermal cycling fatigue life of electronic packaging structures, which confirms the significance of the UCP model reasonably coupled with the intrinsic description of damage by the concept of entropy generation.

Thermal fatigue crack growth behavior of Ni60 coating and bonding area on 20CrNiMo alloy strengthened by laser shock processing

After the laser cladding repair of the brake disc surface in high-speed trains, thermal fatigue cracks in the cladding layer and bonding area are easily observed during the service process. With the aim of solving this problem and decreasing hidden risks, effects of laser shock processing (LSP) on the thermal fatigue life and crack growth behavior of the coating and bonding area of the brake disc were investigated. The results indicate that LSP can refine the columnar grain structures of the cladding layer and bonding area while simultaneously converting residual tensile stress into compressive stress; as a result, the thermal fatigue performance of the brake disc repaired by laser cladding is enhanced. After strengthening by LSP, on the one hand, grain refinement made the structure more uniform and generated more grain boundaries; on the other hand, a pre-set compressive stress field in the cladding layer and bonding area existed. Both aspects were beneficial to dissipate the alternating stress generated by the thermal fatigue process, dissipating the driving force of crack extension and promoting the transformation of thermal fatigue cracks from lateral growth along the interface between the cladding layer and bonding area to the growth into the substrate.