Energy Density Range Research Articles

Application of high-pressure homogenization to steer the technological functionalities of chia fibre-protein concentrate

Chia is an excellent source of healthy constituents (dietary fibre and proteins) with high water holding capacity (WHC) and strong gelling properties, which imply technological challenges for its application in foods, such as leavened bakery products. Therefore, this work explored the potential of high-pressure homogenization (HPH) to steer the technological functionalities (physicochemical, structural and rheological properties) of a chia fibre-protein concentrate (FPC) for food applications. Chia FPC suspensions (5%, w/w) were treated at increasing pressures (up to 150 MPa) and number of cycles (up to 5) to generate a wide range of energy densities delivered to the sample during processing (100–750 MJ m−3). HPH treatments decreased particle size, WHC and oil holding capacity of FPC. WHC of treated samples was 52–70% lower than control. Moreover, rheological measurements on the soluble fraction of homogenised FPC showed a reduction in apparent viscosity and shear-thinning behaviour. These results can be attributed to multiple events occurring during HPH processing. In particular, the mechanical forces suffered by the samples induced the rupture of native structures in smaller fragments in concomitance with biopolymer structure modifications. HPH at energy densities between 300 and 750 MJ m−3 determined a 14–35% increase in soluble dietary fibre (SDF) compared to control, indicating a partial conversion from insoluble to SDF without changes in total dietary fibre. Conformational changes in proteins were also observed. This study suggests that proper selection of HPH energy density represents a strategy to obtain novel promising ingredients rich in dietary fibre and proteins with tailored technological functionalities.

Effects of Power and Laser Speed on the Mechanical Properties of AlSi7Mg0.6 Manufactured by Laser Powder Bed Fusion

The AlSi7Mg0.6 alloy, with its good tolerance against strain, is used in laser powder bed fusion (LPBF) to produce parts with complex geometries for aerospace engineering. Production of parts with good mechanical strength requires, however, the optimization of laser parameters. This study thus evaluated the influence of scanning speed, laser power, and strategy on several mechanical properties (tensile/resilience/hardness) to identify an optimal processing region. Results have shown the profound influence of laser power and scanning speed on mechanical properties, with a limited influence from the laser strategy. Tensile strength values ranging from 122 to 394 MPa were obtained, while Young's Modulus varied from 17 to 29 GPa, and the elongation at break ranged from 2.1 to 9.8%. Surface plots of each property against laser power and speed revealed a region of higher mechanical properties. This region is found when using 50 µm thick layers for energy densities between 25 and 35 J/mm3. Operating at higher values of energy density yielded sub-optimal properties, while a lower energy density resulted in poor performances. Results have shown that any optimization strategy must not only account for the volumic energy density value, but also for laser power itself when thick layers are used for fabrication. This was shown through parts exhibiting reduced mechanical performances that were produced within the optimal energy density range, but at low laser power. By combining mid-speed and power within the optimal region, parts with good microstructure and limited defects such as balling, keyhole pores, and hot cracking will be produced. Heat-treating AlSi7Mg0.6 parts to T6 temper negatively affected mechanical performances. Adapted tempering conditions are thus required if improvements are sought through tempering.

Enhanced proton pseudocapacitive of Ti3C2Tx in neutral electrolyte activated by acid regulation dynamic pillars

Aqueous Zinc ion capacitors (ZICs) using 2D transition metal carbides or nitrides (MXenes) have extraordinary energy density and wide potential range. However, low pseudocapacitance and slowly divalent charges (e.g., zinc ions) transfer in MXene nano sheets are the essential issues in exploring MXene-based ZICs of greater energy densities. Herein, the strategy of using Al3+ as dynamic acid regulation pillars is demonstrated to address these issues. Attributing to dynamically expanded layer spacing, adjustable acid of electrolyte and excited proton pseudocapacitance, enhanced capacity values of 277.9 F g-1 with a high voltage range from -1 to 0.3 V is achieved. The energy density of asymmetric ZICs constructed applied this strategy exhibits superior energy densities of 37.7 Wh kg-1 with outstanding cycling stability, which has been greatly improved compared with traditional acidic and neutral electrolytes. DFT calculations reveal the enhancement mechanism of acid regulation dynamic pillars on electrochemical performance. Our study provides a pathway for precise control of Ion selectivity in MXene energy storage process, and could be further used for other electrolyte systems and aqueous Zn-ion electrodes as well.

Children’s Portion Selection Is Predicted by Food Liking and Is Related to Intake in Response to Increased Portions

When children choose amounts of food to eat, it is unclear what influences the portions they select and whether their selections are related to the amounts they consume. Using a computer survey, we investigated the effect of food liking on portion selection in middle childhood and examined how children's selections were related to measured intake at meals in which portions of all foods were varied across 4 test days. Fifty-one children aged 7-10 y completed a computer survey of 20 common foods with a range of energy density. For each food, the survey presented sliding scales with 5 images varying in portion size and children indicated their liking and the amount they would eat at a specified meal or snack. On 4 test days in a randomized crossover design, children were served a meal of 6 foods from the survey with portions of 100%, 133%, 167%, or 200% of baseline amounts. Data were analyzed using random coefficients models. Across the 20 foods used in the survey, portion selection ratings were predicted by food liking ratings (P<0.0001). After accounting for liking, portion selection ratings did not vary by food energy density (P=0.50). At the meals, intake of all 6 foods increased when larger portions were served (P=0.002). Furthermore, the selected portion of a food on the survey was positively related both to intake of that food at the 100%-portion meal (P=0.014) and to increased intake as larger portions were served (P<0.0001). Children aged 7-10 y were able to use a computer survey to choose food portions that predicted their measured intake in response to increased portions. The relation of liking to selection and intake indicates that to promote children's consumption of larger portions of low-energy-dense foods such as fruits and vegetables, these foods must be well liked by the children. This trial was registered at clinicaltrials.gov as NCT02759523.

Laser powder bed fusion of titanium aluminides using sequential thermal scanning strategy

Titanium Aluminides (TiAls) are good candidates for many applications in the automobile, aerospace, and energy industry because of their high strength, toughness, corrosion, and oxidation resistance at high temperatures. Nevertheless, the low ductility and fracture toughness makes processing of TiAls extremely difficult. Laser powder bed fusion (L-PBF) can additively manufacture high-quality components of various materials. The micro layer-based nature of this process allows for design freedom and near-net shape products. The rapid cooling rates during the L-PBF process may cause defects during the manufacturing of hard materials such as TiAls. These rapid cooling rates lead to high induced residual stresses and crack formation. Several heating strategies and post-heat treatments methods are presented in the open literature for reducing the cracks formed during the L-PBF of TiAl. This study presents a new, novel scanning strategy for mitigating the cracks and reducing residual stresses in the L-PBF of Ti-48Al-2Cr-2Nb. This scanning strategy, referred to as sequential thermal scanning (STS) strategy, applies three thermal cycles in each layer: pre-heating selective area of the powder, melting a layer of powder, and post-heating the solidified layer. The laser process parameters used in each step of the STS strategy were determined and explained in this study. The thermal cycles applied in this scanning strategy were verified using an infra-red thermal camera. Sets of process parameters were studied in the melting step of the STS strategy using a factorial design of experiments. These sets of process parameters cover a large range of volumetric energy density (17–2917 J/mm3). The powder morphology, composition, and behavior were studied. The TiAl fabricated parts were investigated for bulk density, surface and internal cracks, balling defects, internal pores, and surface quality. The spatter formation was studied using a high speed camera. Process maps for the relationship between the laser process parameters and part defects were formulated. Residual stresses were measured to understand the influence of the STS strategy and its effects on the surface features and cracks. The results showed that the STS strategy could be used to produce parts of approximately 99 % density without internal pores. In addition, the STS strategy minimized the amount of internal micro-cracks in TiAl parts. This study contributes to the mitigation of internal defects in the L-PBF of TiAl using a sequential thermal scanning (STS) strategy.

Strain-Enhanced Phase Transformation of Iron Oxide for Higher Alcohol Production from CO2

Conversion of CO2 to higher alcohols (HAs) and higher hydrocarbons (HCs) has a greater advantage compared to C1 products because of their high energy density and wide range of applications in daily life. Despite the immense potential of these chemicals, not much of scientific research has been focused on the conversion of CO2 to HAs. In the present work, we have introduced the concept of strain in designing the material to enhance the CO2 to HA performance. We introduced strain in a traditional iron-based catalyst, Fe2O3, by the introduction of indium (In), which facilitates the selective conversion of CO2 to HA. An optimum strain favored a 36.7% CO2 conversion with a 42% HA selectivity, and a record yield of 15.42%. The strain has been tuned further with the introduction of K as a promoter. The introduced strain upon In substitution and K promotion favored the conversion of CO2, which is mapped by powder X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Further, the change in the mechanism upon In incorporation and K promotion has been probed by in situ diffuse reflectance infrared fourier transform spectroscopy, and it is found that the OCHx intermediate, which produces HAs, is more prominent upon In substitution, which favored the enhancement of HA production compared to that of pristine Fe2O3.

Enhanced Strength and Hardness of AS41 Magnesium Alloy Fabricated by Selective Laser Melting

AS41 magnesium alloy possesses outstanding performance features such as light weight, high strength to toughness ratio and excellent heat resistance due to the addition of Si element, while traditional casting methods are prone to inducing large grain size and coarse Mg2Si phase. In this study, we first reported utilizing the selective laser melting (SLM) technique, fabricating AS41 samples and exploring the effect of laser energy densities on the metallurgical quality by characterizing and investigating the microstructure and mechanical properties. Results showed that the optimal laser energy density range was 60 to 100 J/mm3. Average grain size of only 2.9 μm was obtained with weak texture strength of 1.65 in {0001} orientation. Meanwhile, many dispersed secondary β-Mg17Al12 and Mg2Si phases were distributed inside the α-Mg matrix. It was confirmed that the SLM process introduced more grain recrystallization, inducing giant high-angle grain boundaries (HAGBs) and hindering the movement of dislocations, therefore forming dislocation strengthening while achieving grain refinement strengthening. Finally, three times the ultimate tensile strength of 313.7 MPa and higher microhardness of 96.4 HV than those of the as-cast state were obtained, verifying that the combined effect of grain refinement, solid solution strengthening and precipitation strengthening was responsible for the increased strength. This work provides new insight and a new approach to preparing AS41 magnesium alloy.

Surface Roughness and Biocompatibility of Polycaprolactone Bone Scaffolds: An Energy-Density-Guided Parameter Optimization for Selective Laser Sintering.

Three-dimensional porous polycaprolactone (PCL) bone scaffolds prepared by selective laser sintering (SLS) have demonstrated great potential in the repair of non-load-bearing bone defects. The microgeometry and surface roughness of PCL scaffolds during the SLS process may change the biocompatibility and bioactivity of the scaffolds. However, in addition to the widely concerned mechanical properties and structural accuracy of scaffolds, there is still a lack of systematic research on how SLS process parameters affect the surface roughness of PCL scaffolds and the relationship between roughness and biocompatibility of scaffolds. In this study, we use the energy density model (EDM) combined with the thermodynamic properties of PCL powder to calculate the energy density range (Ed1–Ed3) suitable for PCL sintering. Five PCL scaffolds with different laser powers and scanning speeds were prepared; their dimensional accuracy, mechanical strength, and surface properties were comprehensively evaluated, and the bioactivities were compared through the attachment and proliferation of MC3T3-E1 cells on the scaffolds. It was found that the high energy density (Ed3) reduced the shape fidelity related to pore size and porosity, and the dense and smooth surface of the scaffolds showed poor cytocompatibility, while the low energy density (Ed1) resulted in weak mechanical properties, but the rough surface caused by incomplete sintered PCL particles facilitated the cell adhesion and proliferation. Therefore, the surface roughness and related biocompatibility of PCL bone scaffolds should be considered in energy-density-guided SLS parameter optimization.

Comparison between continuous and modulated wave laser emission modes for the selective laser melting of Ti-6Al-4V: Dimensional accuracy, microstructure and mechanical behaviour

This study investigated the difference between the properties of Ti-6Al-4 V alloy parts printed using continuous wave (CW) and modulated wave (MW) laser emission modes, with equivalent input energy densities. Laser powers in this powder bed fusion process, were systematically altered to evaluate the effect of different input energies on the as-built parts. Printed alloy parts were obtained across five equivalent laser energy densities, in the range of 31–51 J/mm3, investigated using the two laser emission modes. The impact of changes in laser emission mode and energy density was examined based on printed part dimensions, microstructure, porosity, hardness and tensile properties. It was demonstrated that microstructural refinement occurs as a function of melt pool size, which was associated with the penetration depth of the laser energy. The microstructure of samples produced using CW laser emission mode were characterised by thinner laths and narrower prior β grains. Tensile testing according to ASTM E8M, obtained at the different energy levels, demonstrated that over the energy density range investigated there was up to a 17.4% increase in yield strength (YS) and a 2.5% increase in Ultimate Tensile Strength (UTS) for the CW printed samples, when compared with those obtained using the MW laser wave emission mode. Comparatively, MW laser emission mode resulted in thicker laths with slightly wider prior β grains, which exhibited an elongation at break of 13.6% during tensile testing at high energy densities. The influence of the laser emission mode on dimensional accuracy was also investigated. Sample printed using the MW laser emission mode showed up to a 50% improvement in dimensional accuracy when compared with that obtained for CW wave laser emission mode.

3D printing externally reinforced layers for high-speed railway brake discs: Adaptability of SLM processes for manufacturing gradient materials

In this paper, the quasi-continuous ratio gradient alloy steel for the high-speed railway brake disc is prepared by selective laser melting (SLM). While maintaining the strength of the 24CrNiMo alloy steel at the core, it significantly improves the external wear and corrosion resistance of the material. The composition of the designed gradient alloy steel is x% 24CrNiMo + (1-x)% wear-corrosion resistant stainless steel (x is 100, 65, 35 and 0). Through the 20 groups of processes, the optimal process parameters of each gradient are summarized. Besides, the density, surface roughness and residual stress of the material are systematically characterized. The scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) are used to study the types of defects and formation mechanisms in the SLM process. The results show that the optimal laser energy density (LED) range for gradient alloy steel is 56 J mm−3 to 47.8 J mm−3. With the increase of LED, the density of the alloy first increases then decreases, and the type of defects changes from spheroidization defects to cracking. The sample with the best process parameter has a good metallurgical bonding between the gradients, which lays a good foundation for the subsequent analysis of wear resistance and corrosion resistance.

Photobiomodulation for Tendinopathy: A Review of Preclinical Studies.

The outcomes of clinical studies utilizing Photobiomodulation on tendon disorders are not homogeneous and since its design depends on preclinical studies utilizing animal models as a prerequisite, this review investigates the literature to help extrapolate preclinical evidence-based outcomes (safety and efficacy) into clinical treatment options. PubMed and Embase databases were searched for tendinopathy, Photobiomodulation and preclinical studies with inclusion criteria were restricted to in vivo animal studies using rat's models subjected to partially injured tendons. Data extracted were methodology quality and design, light parameters, study methods, and outcomes. Twenty two articles were included, half of them were partially transected, while the other half were partially traumatized. The most common wavelengths used were 660, 830, and 904 nm with energy density range between 1 and 17 J/cm2 and applied mostly daily. Fourteen studies (64%) relied merely on a single assessment. Histological measurements were the most common method of evaluation (75%) and 35% of studies used chemical measures. Mechanical outcomes were reported in four, and two studies demonstrate significant effects. Photobiomodulation has the potential to enhance tendon structure and function, however, inevitable embedded heterogeneity related to study design and quality of methods, light parameters delivered, and evaluations methods renders the ability to establish unified treatment parameters difficult. Adjustments for variability within preclinical studies might lead to better designing of clinical studies. It is recommended to embrace a protocol for designing and performing preclinical studies to improve its quality. Moreover, it is recommended to prove efficacy using at least two evaluation methods and apply Photobiomodulation as a combined varying energy/wavelength protocol (several energies with several wavelengths). Clinical relevance: Establishing a proof of concept for Photobiomodulation that may lead to further high-quality clinical studies, in which the applicable parameters can be determined.

Fabrication of carbon nanofibril/carbon nanotube composites with high sulfur loading from nanocellulose for high-performance lithium‑sulfur batteries

Recently, lithium‑sulfur batteries have attracted much more attention due to their high specific capacity, energy density and wide range of sources. Here, a simple method to prepare sulfur host material was explored. In this method, carbonized cellulose nanofibrils doped with carbon nanotubes were used as the matrix and applied in the cathode. It was found that the sample 40-CNFC with the mass ratio of carbon nanotubes to cellulose dry weight of 4:6 showed the best three-dimensional porous network structure, and its specific surface area was up to 254.4 m2 g−1. After loading sulfur, the initial specific capacity of 40-CNFC@S was 1168 mAh g−1 at 0.1C, and the initial specific capacity of 858 mAh g−1 was still up to 739 mAh g−1 after 120 cycles at 0.5C, providing an available access for designing a promising electrode material for lithium‑sulfur batteries.

Radiation from global topological strings using adaptive mesh refinement: Methodology and massless modes

We implement adaptive mesh refinement (AMR) simulations of global topological strings using the public numerical relativity code, GRChombo. We perform a quantitative investigation of the dynamics of single sinusoidally displaced string configurations, studying a wide range of string energy densities $\mu \propto \ln{\lambda}$, defined by the string width parameter $\lambda$ over two orders of magnitude. We investigate the resulting massless (Goldstone boson or axion) radiation signals, using quantitative diagnostic tools to determine the eigenmode decomposition. Given analytic radiation predictions, we compare the oscillating string trajectory with a backreaction model accounting for radiation energy losses, finding excellent agreement. We establish that backreaction decay is accurately characterised by the inverse square of the amplitude being proportional to the inverse tension $\mu$ for $3\lesssim \lambda \lesssim 100$. We conclude that analytic radiation modelling in the thin-string (Nambu-Goto) limit provides the appropriate cosmological limit for global strings. We contextualise these results with respect to axions and gravitational waves produced by cosmic string networks.

Evaluation of the membrane performance of ultra-smooth silicon organic coatings depending on the process energy density

Plasma-enhanced chemical vapor deposition (PECVD) can be used to apply thin layers to plastics with a wide range of customizable functionality. The selective permeation properties of the layers are particularly interesting for the application field of membrane gas separation processes. In order to be able to produce plasma polymerized membranes in an application specific manner, it is necessary to be able to correlate the plasma process parameters, such as the energy density introduced into the system, with the coating and thus separation properties. Within the scope of this work, different layers produced in a Plasma-enhanced chemical vapor deposition process were investigated with respect to their growth behavior, topographic and chemical properties as well as permeability to evaluate their performance as separation layers of a membrane. The results of the investigations show a strong dependence of the layer and separation properties on the pulsed microwave (MW) power coupled into the process. Energy input was varied over the MW power level as well as the MW pulse duration. Analysis shows the highest permeation and separation performance of the produced layers in the low energy density range of the process.

Effects of powder compression and laser re-melting on the microstructure and mechanical properties of additively manufactured parts in laser-powder bed fusion

Achieving good surface profile and low levels of porosity are prime challenges in the Laser-Powder Bed Fusion (L-PBF) additive manufacturing technique. In order to optimise these properties, post-processing is often required. However, the compression of powder spread on the build plate and re-melting of each build layer during the L-PBF process could address these challenges. In this study, the effect of different powder compression ratios and laser re-melting regimes on the density, microstructure morphology, surface profile and mechanical properties of L-PBF produced parts were investigated. Two different metal printers with same laser processing parameters were used to fabricate 10 × 10 × 10 mm3 stainless steel 316L samples. To examine the impact of compression ratio and layer re-melting, one set of samples was prepared with three different compression levels for each layer and a second set of samples either a single or double set of laser passes for each layer. The Volumetric Energy Density (VED) range examines was from 26.7 J/mm3 to 80 J/mm3. Density, hardness, elastic modulus, microstructure and surface profiles of the printed samples were characterised. A 3% increment in density and a 50% reduction in the surface roughness were achieved using a laser double pass over each layer. The results demonstrate, by applying different powder compression ratios onto the powder bed and by re-melting each layer, that the density, surface roughness and the elastic modulus of the produced samples can be improved.

Laser-assisted mask-free patterning strategy for high-performance hybrid micro-supercapacitors with 3D current collectors

Planar micro-supercapacitors (MSCs) as a promising energy storage device have been widely used in portable, wearable, and implantable electronics. However, the energy density is still limited by the plane configuration and relatively low loading of electrode active material. Here, we reported a facile approach to fabricate the interdigitated current collectors architecture by direct laser engraving of nickel (Ni) foams, followed by electrodeposition of pseudocapacitive materials for fabricating all-solid-state 3D MSCs devices. The fabricated hybrid AMSC (Ni foam-MnO2//Ni foam-PPy) presented a large areal capacitance of 59.29 mF/cm2 at 1 V/s and excellent capacity retention of 95.6% after 10,000 cycles. Moreover, the hybrid Ni foam-based AMSC exhibited a high areal energy density range from 42.99 to 77.94 μWh/cm2 with a corresponding power density range from 0.272 to 6.818 mW/cm2. This prototype of laser-assisted all-solid-state AMSC demonstrates the potential of Ni foam-based energy storage devices applications for 3D MSCs that require high energy density.

Influence of water environment on paint removal and the selection criteria of laser parameters

Laser paint removal in a water environment does not diffuse ablation pollution products into air. Characteristics of water, such as high specific heat and heat flux, generate different effects of the laser paint removal than in an air environment. In this study, the effects of air and water environments on the mechanism and effect of laser paint removal are analyzed and compared experimentally and theoretically. In air, thermodynamic ablation causes removal of paint, whereas in water, stress coupled with plasma shock waves cause tear and splash removal of paint layers after fracture and damage. Fracture and pressure thresholds of the paint and substrate, respectively, indicate the optimum energy density range for laser paint removal in water, providing a reference for engineering applications.

Design of a high-resolution Rayleigh-Taylor experiment with the Crystal Backlighter Imager on the National Ignition Facility

The Rayleigh-Taylor (RT) instability affects a vast range of High Energy Density (HED) length scales, spanning from supernova explosions (1013 m) to inertial confinement fusion (10-6 m). In inertial confinement fusion, the RT instability is known to induce mixing or turbulent transition, which in turn cools the hot spot and hinders ignition. The fine-scale features of the RT instability, which are difficult to image in HED physics, may help determine if the system is mixing or is transitioning to turbulence. Earlier diagnostics lacked the spatial and temporal resolution necessary to diagnose the dynamics that occur along the RT structure. A recently developed diagnostic, the Crystal Backlighter Imager (CBI), [1,2] can now produce an x-ray radiograph capable of resolving the fine-scale features expected in these RT unstable systems. This paper describes an experimental design that adapts a well-characterized National Ignition Facility (NIF) platform to accommodate the CBI diagnostic. Simulations and synthetic radiographs highlight the resolution capabilities of the CBI in comparison to previous diagnostics. The improved resolution of the system can provide new observations to study the RT instability's involvement in mixing and the transition to turbulence in the HED regime.

Towards the additive manufacturing of Ni-Mn-Ga complex devices with magnetic field induced strain

Laser powder bed fusion ( L -PBF) is used to produce foam-like Ni-Mn-Ga with tailored microscale and mesoscale features. Ni50-Mn28.2-Ga21.8 (at%) powder was gas atomised and processed in an L -PBF system with a range of energy density from 26.24 and 44.90 J/mm 3 . We characterised microscale and mesoscale properties, such as the chemical composition, crystal structure, magnetisation measurements, density, and porosity measurements as a function of process parameters, in a systematic design of experiment. Preliminary research on macroscale properties included tensile testing and magnetic field induced strain (MFIS) measurements. Results show how controlling process parameters allows tailoring the Ni-Mn-Ga polycrystalline microstructure. Hence, obtaining twinned martensitic structures with a predominant orientation going across the visible grain boundaries. All the processed samples showed a 56 Am 2 /kg magnetisation level, close to Ni-Mn-Ga 10 M single crystals. Mesoscale results show a distinctive porosity pattern that is tailored by the process parameters and the laser scanning strategy. In contrast, macroscale mechanical tensile test results show a brittle fracture of Ni-Mn-Ga due to the high porosity with yield stress 2–3 times higher than shown in single crystals. In sum, we built geometrically complex demonstrators with (i) microscale twinned martensitic structures with a predominant orientation going across the visible grain boundaries and (ii) mesoscale tailored periodic porosity patterns created by modifying power, scanning speed, and scanning strategy systematically. L -PBF demonstrates great potential to produce foam-like polycrystalline Ni-Mn-Ga, reducing grain boundary constraints and thus the magnetic force needed for MFIS.

Thermal Fatigue Life Prediction of BGA Solder Joint Incorporating Microstructural Coarsening Effect due to Thermal Diffusion.

A creep constitutive equation incorporating the effect of microstructure coarsening was introduced into the Finite Element Method analysis using a user subroutine to predict thermal fatigue life of solder joint. Dispersed particles in the microstructure grew due to thermal diffusion with increasing fatigue cycles, which resulted in the inelastic strain range and the inelastic strain energy density range increased. This increase in the inelastic strain range reduced the fatigue life by approximately 77% compared to the case where no microstructure coarsening effect was incorporated. Thus, it is necessary to incorporate the microstructure coarsening effect in the fatigue analysis of solders. Thermal fatigue life was found to be significantly affected by the microstructure coarsening effect. Thus, it is necessary to incorporate the microstructure coarsening effect in the fatigue analysis of solders.