Changes In Material Composition Research Articles

Comprehensive new insights on the potential use of SiC as plasma-facing materials in future fusion reactors

The performance of silicon carbide as an alternative plasma facing material (PFM) was studied at various irradiation conditions relevant to ion energies and fluxes of a fusion reactor. This analysis involves detailed modeling of subsurface plasma/material interactions, sputtered particle transport above the surface and redeposition, and related changes in material composition and microstructure induced by steady-state and Edge Localized Mode ion fluxes. Transition of a crystalline SiC surface to semi-crystalline and amorphous phases was analyzed based on advanced modeling of DIII-D tokamak experiments where SiC was irradiated in single- and multiple- L-mode and H-mode discharges. This analysis shows that displacement damage, particle deposition/redeposition, and D accumulation on the SiC divertor surface can lead to significant microstructural changes that result in enhanced sputtering erosion in comparison with the original crystalline material. However, the resulting total net erosion rate for a full-coverage, advanced tokamak, SiC coated divertor may well be acceptably low. Moreover, the C sputtering yield from the evolved SiC surface can be seven times lower than from a pure graphite surface; this would imply significantly reduced tritium co-deposition rates in a D-T tokamak reactor, compared with a pure carbon surface. It was also determined that chemical sputtering of both C and Si should not result in any noticeable effect on the net erosion, for attached plasma regimes. Our results thus show encouraging results overall for use of SiC as a PFM in tokamaks.

Enzymatic Changes in the Chemical Composition of Cigar Tobacco Raw Materials in an Alcohol-containing Medium of an Oak Barrel from Under Cognac Distillate

Enzymatic Changes in the Chemical Composition of Cigar Tobacco Raw Materials in an Alcohol-containing Medium of an Oak Barrel from Under Cognac Distillate

Experimental investigation on selective laser melting additive manufacturing of non-ferromagnetic heterogeneous material based on TiNi alloy with Ta coating

In order to manufacture non-ferromagnetic heterogeneous material by Selective Laser Melting (SLM), it is necessary to solve the separation problem of non-ferromagnetic mixed powders after SLM forming. This research presents how to resolve this problem using TiNi/Ta mixed powders by ultrasonic vibration screening method and the analysis of SLM manufacturing experiment for non-ferromagnetic heterogeneous material. The purity of TiNi and Ta powders after separation could reach 99.7087%wt% and 98.8501wt% respectively, which both reached a relatively high purity. A TiNi alloy sample with Ta coating and TiNi/Ta gradient transition was manufactured successfully by SLM. The material interface of the sample achieves metallurgical bonding, and the color of the sample profile shows a gradient transition. The EDS analysis shows that the material composition changes from Ta ->Ta/TiNi gradient ->TiNi from surface to inside of the sample. The Ta coating contains over 92.5wt% Ta, and the TiNi matrix contains over 98.69wt% TiNi. Along the powder laying direction, it is difficult to clean the small powder near the solid-powder or solid-solid interfaces made of two different materials, which causes micro polluted areas near the interfaces. This study also provides a new method for integrated manufacturing of TiNi alloy part with Ta coating.

Effect of alkaline pre-treatment on hydrolysis rate and methane production during anaerobic digestion of paunch solid waste

Paunch is comprised of the partially digested feed contained in cattle or sheep and contributes 20–50% of organic waste produced at red meat processing facilities. Anaerobic digestion has been identified as a promising technology for paunch treatment, however treatment times can be long and when combined with the moderate degradability of paunch this results in high treatment costs that need to be improved. Pre-treatment was investigated as a strategy to improve AD of paunch, alkaline treatment (NaOH or KOH) was selected due to the high lignin content. A range of alkaline loadings (1–20 g 100gTS−1) were tested with an equivalent hydroxide molar concentration of 9–250 mM [OH−]. Alkaline pre-treatment improved both the hydrolysis rate and the overall degradability of paunch solid by up to 4.4 times and 60%, respectively. The enhanced hydrolysis rate and methane yield was correlated to changes in material composition during pre-treatment. While alkaline concentration was an important factor, there were no significant improvements at alkaline concentrations above 12 g 100gTS−1 (150 mM [OH−]).

Strength and Deformation Behavior of Equestrian Riding Surfaces Improved with Recycled Geosynthetics

Abstract Recycled geosynthetic materials can be incorporated into sand-based soils to improve their shear characteristics and enhance surface response in different engineering applications. This paper summarizes research undertaken to explore the effect of recycled geosynthetic components added to silica sand, whose complex and engineered soil matrix is currently used in the equestrian riding industry. Approximately 120 direct shear tests were used to evaluate the shear strength and compressibility behavior of several riding surface mixtures blended with a combination of short polymer fibers and cut-up pieces of geotextile fabric along with other components such as crumb rubber and binding agents. As expected, results suggest that the shear characteristics of these surfaces are very sensitive to changes in material composition as geosynthetics are incorporated into the soil matrix. It was demonstrated that the addition of geosynthetics can significantly increase the shear strength of granular materials. Although these tests were initially performed for equestrian riding surface applications, the findings of this research could be used for other engineering applications (e.g., lightweight fills, temporary roadways, etc.).

Hormonal and non-hormonal oral contraceptives given long-term to pubertal rats differently affect bone mass, quality and metabolism.

We investigated the effects of hormonal and non-hormonal oral contraceptives (OCs) on bone mass, mineralization, composition, mechanical properties, and metabolites in pubertal female SD rats. OCs were given for 3-, and 7 months at human equivalent doses. The combined hormonal contraceptive (CHC) was ethinyl estradiol and progestin, whereas the non-hormonal contraceptive (NHC) was ormeloxifene. MicroCT was used to assess bone microarchitecture and BMD. Bone formation and mineralization were assessed by static and dynamic histomorphometry. The 3-point bending test, nanoindentation, FTIR, and cyclic reference point indentation (cRPI) measured the changes in bone strength and material composition. Bone and serum metabolomes were studied to identify potential biomarkers of drug efficacy and safety and gain insight into the underlying mechanisms of action of the OCs. NHC increased bone mass in the femur metaphysis after 3 months, but the gain was lost after 7 months. After 7 months, both OCs decreased bone mass and deteriorated trabecular microarchitecture in the femur metaphysis and lumbar spine. Also, both OCs decreased the mineral: matrix ratio and increased the unmineralized matrix after 7 months. After 3 months, the OCs increased carbonate: phosphate and carbonate: amide I ratios, indicating a disordered hydroxyapatite crystal structure susceptible to resorption, but these changes mostly reversed after 7 months, indicating that the early changes contributed to demineralization at the later time. In the femur 3-point bending test, CHC reduced energy storage, resilience, and ultimate stress, indicating increased susceptibility to micro-damage and fracture, while NHC only decreased energy storage. In the cyclic loading test, both OCs decreased creep indentation distance, but CHC increased the average unloading slope, implying decreased microdamage risk and improved deformation resistance by the OCs. Thus, reduced bone mineralization by the OCs appears to affect bone mechanical properties under static loading, but not its cyclic loading ability. When compared to an age-matched control, after 7 months, CHC affected 24 metabolic pathways in bone and 9 in serum, whereas NHC altered 17 in bone and none in serum. 6 metabolites were common between the serum and bone of CHC rats, suggesting their potential as biomarkers of bone health in women taking CHC. Both OCs have adverse effects on various skeletal parameters, with CHC having a greater negative impact on bone strength.

Fabrication of structurally graded material (pure PLA/WFPC): Mechanical and microscopic aspects

The aim of this study is to provide first-hand knowledge on additively manufactured structurally graded material (SGM) (polylactic acid / wood-fiber polymer composites) wall. Polylactic acid or polylactide is most effectively used in manufacturing plastic films, bottles, biodegradable medical devices, textile, and agricultural goods. Wood-fiber polymer composites are essentially used in furniture, particleboard, oriented strand board, medium-density fibreboard, plywood, and constructions. SGM is characterized through the change in material composition that is applicable to specific functions. Fabricated SGM exhibited mechanical property such as tensile strength (15.78 ± 0.05 MPa), compressive strength (46.8 ± 2.7 MPa), flexural strength (88.2 ± 0.15 MPa), and impact energy (1.64 ± 0.07 J). Hardness value of SGM is 74.5 shore-D. The coupon studies revealed that SGM possesses better mechanical characteristics than wood-fiber polymer composites and is on par with polylactic acid. The observed morphologies on fracture surface indicate the brittle nature of fracture. This SGM come under advanced materials that are utilized in biomedical, defence, energy, aviation, and nuclear sector, for integrated structural and thermal application.

Consolidation behaviour of palm-oil-fuel-ash-based geopolymer treated soil

In recent times, geopolymers have gained attention as a soil stabilisation binder due to their ability to improve the engineering properties of soil while remaining eco-friendly. This study seeks to investigate the stabilisation of soft soil using palm-oil-fuel-ash (POFA)-based geopolymers. A geopolymer was created by combining POFA with an alkaline activator solution composed of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The mechanical and microstructural behaviours of two clayey soil types (samples S1 and S2) stabilised with four doses of the POFA-based geopolymer (G10PA, G20PA, G30PA and G40PA) were studied by conducting one-dimensional consolidation, California bearing ratio (CBR) tests, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The optimum dosage found was G40PA for both soil samples. The CBR value of S1-G40PA was 1.7 times that of S1, while that of S2-G40PA was nearly 1.5 times that of S2. The void ratio of S1 was significantly reduced from 0.70 (untreated sample) to 0.56 (S2-G40PA), whereas for S2, it was decreased from 1.43 (untreated sample) to 0.43 (S2-G40PA). The microstructural analysis (FESEM) revealed that changes in material composition correlate with the consolidation behaviour, with the geopolymer gel-binding effect enhancing the mechanical properties of stabilised soils.

Evaluation of the efficiency of sugar beet processing strategies based on the data of the Sergach Sugar Factory

This study is devoted to evaluation of the effectiveness of sugar beet processing strategies, considering the factor of reducing the purity of sugar-containing solutions as a result of long-term storage of raw materials in the conditions of a specific manufacturer - Sergach Sugar Factory. The purpose of the work is to formulate recommendations on the selection of the most effective strategy for manufacturers based on assessments of the effectiveness of various sugar beet processing strategies. As a result of the study, the effectiveness of two heuristic strategies for sugar beet processing was evaluated - “greedy” and “thrifty”. The implementation of both strategies does not require a priori knowledge of all information about changes in the chemical composition of raw materials during storage and is based on current information about the characteristics of the remaining batches of raw materials to the current moment. The “greedy” strategy involves processing the batch of raw materials that currently gives the highest sugar yield, and the “thrifty strategy” - the batch that gives the minimum yield. The efficiency was evaluated by comparing the loss in sugar yield from the implementation of a heuristic strategy compared to the absolute optimum. When calculating the estimated sugar yield, data on the sugar content of various batches of beets and the purity of sugar-containing solutions in the conditions of the Sergach Sugar Factory in 2021 were considered. As a result of the study, it is shown that the “thrifty” strategy has small advantages compared to the “greedy” one. Thus, when choosing a recycling processing in practice, it is better to give preference to the “thrifty” strategy. This makes it possible to increase the total sugar production per season by 100 tons.

Mechanical sandstone deterioration due to cement binder material materials under dry-wet cycling

The effects of cementitious materials used in the early conservation of stony cultural heritage on sandstones have yet to be clarified. The impact of cementitious materials on mechanical and physicochemical properties was investigated by designing sandstones for wet and dry cycling in neutral and alkaline solutions (pure water, sodium hydroxide, calcium hydroxide, ordinary cement, and low alkaline cement). The sandstone was examined before and after the wet and dry cycles using X-ray fluorescence spectrometry (XRF), ion chromatography (IC), and X-ray diffractometry (XRD) to characterize the deterioration of the sandstone material caused by cement from macro and micro perspectives and the diffusion characteristics of the soluble components of cement in the sandstone. The results show that the concentration of Ca2+ precipitated within the sandstone after cycling is higher than that of Cl-, SO42-, NO3-, Na+, and K+ and has the most significant influence on the sandstone properties. In terms of mass, there is a 3%−6% mass loss in the sandstone after dry and wet cycling in NaOH solution and a 2%−7% mass accumulation in cement and Ca(OH)2 solution. The cumulative damage (DN) variation pattern of sandstones was also analyzed based on wave velocity variation. The damage rate fluctuated in a wider region of 6%−30% for medium-weathered sandstones subjected to dry and wet cycling in cement solution compared to fresh sandstones, and 9%−20% for fresh sandstones. In addition, it was found that the deterioration process of sandstone by cement materials is physicochemically synergistic, while the macro-mechanical properties correspond closely to the changes in material composition.

Research on Influences of Ultrasonic Vibration Agitation Stirring on Carbonation Resistance of Cement-Based Materials after Absorption of CO2

To disclose influences of ultrasonic vibration agitation on the carbonation resistance of cement-based materials after absorption of CO2, the variation laws in internal carbonization zone were explored by the testing carbonization depth and carbonization range (pH variation range) of cement mortar after CO2 absorption at different ages. Results demonstrated that when CO2 absorption volumes of the cement mortar before carbonization were 0.44%, 0.88%, 1.32%, 1.76%, and 2.20% (28 d), the carbonization depth under ultrasonic vibration decreased by 5.5%, 12.3%, 21.7%, 20.7%, and 26.7% compared to those under mechanical stirring, respectively. When the ultimate CO2 absorption volume increased to 2.2% of cement mass, the extended degree of cement mortar was 103.23 mm, which decreased by 5.4% compared to that before CO2 absorption. pH variation values of the carbonization range under ultrasonic vibration presented a rising trend with the increase of CO2 absorption volume of cement mortar before carbonation. This indicated that, with the increase of CO2 absorption volume of cement mortar before carbonation increases under ultrasonic vibration, the carbonization process of the hardened body of cement mortar might be decelerated to some extent. Additionally, changes in internal composition and physical images of cement-based materials after absorption of CO2 were analyzed through microtest means like SEM and XRD. A carbonation resistance model was constructed, thus enabling disclosure of the variation mechanism of carbonation resistance of cement-based materials after absorption of CO2 under mechanical stirring and ultrasonic vibration. Results demonstrated that the higher CO2 absorption volume of fresh slurry generated more “nano-level” CaCO3 crystal nucleus. Accordingly, it could improve the porous structure of the cement mortar, decrease the quantity of capillary tubes significantly, improve the compaction degree of cement-based materials effectively, and lower the diffusion rate of CO2 in the cement paste base, thus improving the carbonation resistance. Research conclusions have important significance to decrease CO2 emissions and improve carbonation resistance of concrete.

Finite Element Simulation of Residual Stress in Laser Additive Manufactured Functionally Gradient Materials Based on Bessel Heat Source Model.

Laser additive manufacturing (LAM) technology has the advantages of short manufacturing cycles, low material waste rate, and design ability. It is especially suitable for preparing functionally gradient materials (FGM). However, due to the large temperature gradient and the change in material composition, the residual stress is very high, which will seriously affect the mechanical properties and manufacturing accuracy of the structure. In this study, the thermomechanical coupled finite element model based on the Bessel heat source is established, and the residual stress in LAM TC4/TC11 FGM is obtained. The results show that the Bessel heat source can effectively suppress the generation of residual stress in the additive manufacturing process, and the finite element results are consistent with the experimental results. Compared with the traditional Gaussian heat source, the maximal residual tensile stress is reduced by an average of 28.1%. The value of residual stress increases with the increase in the number of printing layers, and it increases with the increase of the laser power and decreases with the increase of the scanning speed. The overall trend is that the two sides are compressive stress and the middle is tensile stress. The research has important reference significance for the reasonable suppression of the residual stress in FGM produced by LAM.

Effects of aluminum hydroxide on mechanical, water resistance, and thermal properties of starch-based fiber-reinforced composites with foam structures

Despite the large demand, the current biomass composites still exhibit problems of low mechanical properties, strong hydrophilicity, and poor thermal resistance, which limit biomass composites' application fields. Facing these problems, starch-based fiber-reinforced composites with foam structures were fabricated by hot pressing and foaming process, for the first time. In these composites, the corn starch serves as matrix while the sisal fiber acts as skeleton. Aluminum hydroxide (ATH) has been added to alter microstructures. To identify microstructure and material composition changes induced by ATH, scanning electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy have been performed. Experimental results show that an appropriate ATH content can improve composite's ultimate tensile strength by as much as 37%. Molecular dynamic simulations were performed to understand ATH effects on tensile properties at an atomic level. In addition to tensile properties, the addition of ATH is also beneficial to improve the compressive properties, water resistance and thermal stability of starch-based fiber-reinforced composites, making the composite a potential candidate to replace traditional packaging materials. Therefore, this investigation will benefit the current packaging industry in that sustainable utilization of packaging materials can be realized.

Modeling of Dynamic Operation Modes of IVG.1M Reactor

This paper presents the results of a calculation code approach providing a solution to the point kinetics problem for the IVG.1M research reactor of the National Nuclear Center of the Republic of Kazakhstan and allowing the simulation of dynamic processes going on during reactor start-ups, including changes in the thermal state of all its elements, reactor regulator displacement, accumulation of absorbers in the fuel, and the beryllium reflector. A mathematical description of the IVG.1M point kinetics model is presented, which provides a calculation of the reactor neutron parameters, taking into account the dependence of reactivity effects on the temperature, changes in the isotopic composition of materials, and thermal expansion of core structural elements. An array of data values was formed of reactivity added by separate elements of the core when changing their thermal state and other reactor parameters, as well as an array of data with the parameters of heat exchange of coolant-based reactor structural elements. These are used in the process of solving the point kinetics problem to directly replace formal parameters, eliminating the need to calculate the values of these parameters at each calculation step. Preliminary calculations to form an array of values of reactivity effects was applied to the reactor by separate structural elements when their temperature changes were performed using the IVG.1M precision reactor calculation model. The model was validated by the reactor parameters in the critical state. Preliminary calculations to form an array of data with the parameters of heat exchange of coolant-based reactor structural elements were performed in ANSYS Fluent software using the calculation model that describes the IVG.1M reactor fuel element in detail. Validation of the developed calculation code based on the results of two start-ups of the IVG.1M reactor was performed and its applicability for the analysis of transient and emergency modes of reactor operation and evaluation of its safe operation limits was confirmed.

Probing the Separation Distance between Biological Nanoparticles and Cell Membrane Mimics Using Neutron Reflectometry with Sub-Nanometer Accuracy.

Nanoparticle interactions with cellular membranes are controlled by molecular recognition reactions and regulate a multitude of biological processes, including virus infections, biological nanoparticle-mediated cellular communication, and drug delivery applications. Aided by the design of various supported cell membrane mimics, multiple methods have been employed to investigate these types of interactions, revealing information on nanoparticle coverage, interaction kinetics, as well as binding strength; however, precise quantification of the separation distance across which these delicate interactions occur remains elusive. Here, we demonstrate that carefully designed neutron reflectometry (NR) experiments followed by an attentive selection and application of suitable theoretical models offer a means to quantify the distance separating biological nanoparticles from a supported lipid bilayer (SLB) with sub-nanometer precision. The distance between the nanoparticles and SLBs was tuned by exploiting either direct adsorption or specific binding using DNA tethers with different conformations, revealing separation distances of around 1, 3, and 7 nm with nanometric accuracy. We also show that NR provides precise information on nanoparticle coverage, size distribution, material composition, and potential structural changes in the underlying planar SLB induced upon nanoparticle binding. The precision with which these parameters could be quantified should pave an attractive path for investigations of the interactions between nanoparticles and interfaces at length scales and resolutions that were previously inaccessible. This thus makes it possible to, for example, gain an in-depth understanding of the molecular recognition reactions of inorganic and biological nanoparticles with cellular membranes.

Influence of the Ni Catalyst on the Properties of the Si-C Composite Material for LIB Anodes

The subject of this study was Si-C composites for lithium-ion battery (LIB) anodes obtained by carbonization of nanodispersed silicon with carbon monofluoride. To determine the possibility of increasing the degree of graphitization of nanodispersed carbon forming shells around the silicon particles at lower temperatures, nickel in the form of an alcoholic solution of Ni(NO3)2 was introduced as a catalyst into the pellets of the resulting composite. The XRD, Raman scattering and EDS methods were used to investigate changes both in the phase and elemental composition of materials resulting from the annealing of the Ni-containing Si-C composite over the temperature range of 500–1100 °C. It was found for the first time that nickel silicides that emerged during the annealing became catalysts and, at the same time, intermediate products, of cubic silicon carbide (β-SiC) synthesis, which reduced its temperature formation from ~1100 °C to ~800 °C. The same compounds had a catalytic effect on the carbon atom association, leading to an increase in the degree of its graphitization. The influence of changing the composition of the investigated material on the electrochemical characteristics of the obtained negative LIB electrodes was traced.

Microstructure Effects of the Electrical Discharge Machining Drill on Aerospace Super Alloys

This paper presents an analysis of the parent material damage and electrode wear of a handheld electrical discharge machining (EDM) drill. The motivation of this study is to investigate the material effects of EDM drilling on aerospace alloys at a microstructure level. The specific effects that are being investigated are heat affected zones (HAZ), grain structure changes, material composition changes, and fracturing. A secondary goal of this study is to determine if there is potential for electrode wear prediction models for supply chain management. The study consisted of making cuts into both Inconel and titanium test specimens while varying cut depths and electrode diameters. The results of the study found that the electrode wear while cutting Inconel showed some amount of predictable behavior. On the contrary, the titanium specimens did not indicate a predictable behavior and did not appear to follow an intuitive trend. Interestingly, when drilling into titanium, the active electrode increased in length, indicating that the titanium is being deposited onto the electrode. The EDM drill caused notable damage to the parent material, including a substantial recast layer of up to approximately 150 μm in thickness, incorporation of electrode material into the parent material through the recast layer, and formation of microcracks that can cross the recast layer/parent material interface. These noted characteristics can have an impact on material performance and longevity due to the nonuniform nature of the damage and the introduction of microcracks crossing from the recast layer into the parent material.

Infrared heating modeling of recycled PET preforms in injection stretch blow molding process

Relatively recent citizen’s consciousness about plastic pollution forces industrial actors of packaging to re-invent their shaping processes and materials. Specifically, for plastic bottle industry shaping, classical Polyethylene Terephthalate (PET) material is little by little replaced by recycled PET (rPET). The change in material composition due to recycling loops leads to an inevitable adaptation of the Injection Stretch Blow Molding (ISBM) process used to shape bottles at a satisfactory production rate. Indeed, rPET contains contaminants which modify its optical properties, so the heating stage becomes material-dependent and unstable regarding the polymer supplier. The approach adopted in this article is to build a numerical model able to simulate the infrared heating of rPET preforms, sensitive enough to predict changes in temperature due to the recycling rate. To do so, the optical properties of 50% and 100% rPET are measured by spectrometry and implemented in the simulation. Thermal radiative heat transfer between infrared lamps and rPET preforms is simulated by ray tracing method using an in-house software so-called RAYHEAT. Then, the result of the infrared ray tracing computation is used as the input heat source for thermal simulation by commercial software COMSOL Multiphysic®in order to simulate the temperature distribution of the preform. The numerical results are then confronted to experimental ones obtained on a research Stretch Blow Molding pilot, instrumented with thermography. The results show that the temperature obtained at the end of a classical heating cycle of the 100% recycled grade is 8 °C higher than the virgin one. Also, simulations confirm that this difference is attributed to changes in optical properties. Finally, heating 100% rPET at a sufficient forming temperature is about 8% less energy consuming than for virgin PET.

Process optimization and optimal tolerancing to improve dimensional accuracy of vat-photopolymerized functionally graded hydrogels

Functionally graded hydrogels with variation in material composition are useful for a variety of applications in domains like biomedical engineering and soft robotics. Recent developments in 3D printing have enabled the production of such graded hydrogels. However, the variation in the composition of these hydrogels layer-wise can be challenging in terms of selecting optimal 3D printing process parameters and maintaining geometrical accuracy. Unless corrective measures are taken, the variations in material composition can cause a loss in print fidelity and lead to dimensional deviations in the printed samples. In-depth studies have not been reported to address these challenges in the 3D printing of functionally graded hydrogels, and guidelines are not available for correcting the geometric deviations so produced. In this work, we study the deviations in lateral dimensions in functionally graded polyethylene glycol diacrylate (PEGDA) hydrogels produced using digital light processing (DLP) 3D printer and present a method to correct these deviations. The methodology involves specification of optimal printer parameters for each material composition and giving appropriate tolerances on the CAD model. The lateral dimensions of the printed part depend on PEGDA concentration, exposure time, layer thickness and print time. For obtaining accurate samples after printing and swelling, the printer parameters must be changed whenever a change in material composition occurs. Further, the printer parameters have to be chosen such that swelling induced cracking is reduced while maintaining good print fidelity. The tolerance on the CAD model has to consider the lateral deviation that occurs at the edges due to printing and the bulk increase that occurs due to swelling. We demonstrate this method by printing functionally graded PEGDA samples with good print fidelity and dimensional accuracy.

Finite element analysis for residual stress of TC4/Inconel718 functionally gradient materials produced by laser additive manufacturing

Compared with traditional manufacturing methods, laser additive manufacturing (LAM) has incomparable and huge advantages when preparing functionally gradient materials. However, due to the large temperature gradient and the change of material composition, the residual stress of the structure can be very large, which will seriously affect the mechanical properties of the structure, and cause the structure to bend and crack. In this paper based on the finite element method, the residual stress of TC4/Inconel718 materials widely used in aerospace is studied. And it mainly focuses on the influence of key parameters such as laser energy and material composition of transition layers. The results show that the laser power has a positive correlation with the residual stress of the structure and the change of the residual stress of the contact surface is relatively gentle when the components of the two gradient materials are close. The results obtained are in good agreement with the experiment. The research in this article has reference value for understanding, measuring and reasonably controlling the residual stress of functionally gradient materials by LAM.