Capsule Design Research Articles

ЭКСПЕРИМЕНТ ПО НИЗКОТЕМПЕРАТУРНОМУ ОБЛУЧЕНИЮ ПОРОШКА ФТОРИРОВАННЫХ ДЕТОНАЦИОННЫХ НАНОАЛМАЗОВ В РЕАКТОРЕ ВВР-К: УСЛОВИЯ И ПЕРВИЧНАЯ ХАРАКТЕРИЗАЦИЯ ОБРАЗЦОВ

Fluorine-doped detonation nanodiamond (DND) powders are considered as a new class of neutron reflectors and can significantly improve the performance of very cold and ultracold neutron sources, which in turn will lead to new types of experiments at a qualitative level. These improvements are achieved due to such properties of DNDas high diffusion and quasi-mirror reflection. The high reflectivity improves the neutron delivery efficiency and, consequently, the neutron fluxes at neutron facilities. On this basis, fluorinated DNDs are considered as a potential neutron reflector material for the designed very cold and ultracold neutron source at the WWR-K reactor. However, to date, experimental data on the behaviour of fluorinated DND in the neutron field are insufficient, and therefore, in order to study the radiation resistance of DND at the WWR-K reactor, work has been started on their irradiation and further study. For this purpose, an optimal irradiation capsule design was developed and comprehensive calculations were performed to justify the conditions and limits of reactor irradiation. This paper describes the irradiated samples and reactor experiment, the methodology and conditions for irradiating the samples, and the results of their initial characterisation after irradiation.

Nonlinear flow of couple stress fluid layer over an inclined plate

The issue of stability of a thin couple-stress liquid layer flows on an inclined plane was inspected. The thin-film approximation was employed to obtain a Benney-like differential equation, that described the time record of the interface profile The linear transition state and reduction ratio of maximum classical (Newtonian) growth-rate were discussed. The complete evolution equation was solved numerically using the method of lines in order to support the novelty of the work. The linear stability could be enhanced by increasing the couple-stress coefficient and surface tension as well as reducing the inclination. However, the ordinary viscosity played an irregular role. The linear results predicted conditions (windows) in which the non-Newtonian film was more stable than its Newtonian counterpart. The nonlinear stimulation anticipated the existence of sock waves in certain situations. The appearance of instability through the linear subcritical region as well as irregular influences with respect to surface tension and couple-stress property was revealed. The nonlinear approach was more accurate in describing the stability issue than the linear one. Such results could be employed to attain the optimum statuses with regard to the film stability, and control the shock waves. They would not only enable accurate practical implementation in the design of inertial confinement fusion capsules and supernova explosions and implosions modeling, but also would allow for precise numerical simulation.

Hydrodynamic performance of an elastic capsule oscillating water column type WEC: An experimental study

Wave energy represents a promising and sustainable source of energy with substantial potential. To promote the utilization of wave energy resources as well as develop new wave energy converters (WECs) with application prospects, an innovative elastic capsule oscillating water column (EC-OWC) WEC is proposed, and an initial experimental investigation is conducted on the device. Besides, the expansion characteristics of the elastic capsule and the motion characteristics of the free bulge wave are investigated through bulge wave tests. Moreover, the hydrodynamic performances of the device on the condition that coupled with traveling regular waves are investigated through wave tests, as well as the damping characteristics of the impulse turbine model and the ring-opening as power take-off (PTO) systems in the EC-OWC. It indicates that the variation in the speed of the free bulge wave is consistent with the one-dimensional longitudinal wave theory, that the ring-opening model with an opening ratio of 0.76 percent has comparable operating characteristics to the impulse turbine, and that the impulse turbine model has outstanding operating characteristics in the EC-OWC system. The maximum primary hydrodynamic efficiency of the system is approximately 0.475. When the relative water depth is in the interval of approximately 0.07-0.09, the efficiency can reach 0.4. Furthermore, the efficiency increases and subsequently decreases with the variation of the relative hydraulic head, and the efficiency reaches the maximum value when the relative tube length is around 1.6. The results indicate that the one-dimensional longitudinal wave theory can provide support for the design of the elastic capsule. When the capsule length is close to half a wavelength and the internal and external oscillation periods are matched, the system reaches a near-resonant state, and the level of efficiency is optimized. The bulge wave contained within the EC-OWC is a half-wavelength standing wave.

PH-dependent pressure-sensitive colonic capsules for the delivery of aqueous bacterial suspensions

Microbiome-based therapies hold great promise for treating various diseases, but the efficient delivery of live bacteria to the colon remains a challenge. Furthermore, current oral formulations, such as lyophilized bacterial capsules or tablets, are produced using processes that can decrease bacterial viability. Consequently, high dosages are required to achieve efficacy. Herein, we report the design of pressure-sensitive colonic capsules for the encapsulation and delivery of aqueous suspensions of live bacteria. The capsules consisted of 2 functional thin-films (hydrophobic and enteric) of ethyl cellulose and Eudragit S100 dip-coated onto hydroxypropyl methylcellulose molds. The capsules could be loaded with aqueous media and provide protection against acidic fluids and, to some extent, oxygen diffusion, suggesting their potential suitability for delivering anaerobic bacterial strains. Disintegration and mechanical studies indicated that the capsules could withstand transit through the stomach and upper/proximal small intestinal segments and rupture in the ileum/colon. In vitro studies showed that bacterial cells (anaerobic and aerobic commensals) remained highly viable (74–98%) after encapsulation and exposure to the simulated GI tract conditions. In vivo studies with a beagle dog model revealed that 67% of the capsules opened after 3.5 h, indicating content release in the distal gastrointestinal tract. These data demonstrate that live aqueous bacterial suspensions comprised of both aerobic and anaerobic commensals can be encapsulated and in the future might be efficiently delivered to the distal gastrointestinal tract, suggesting the practical applications of these capsules in microbiome-based therapies.

Point design of octahedral spherical Hohlraum with HDC–CH capsule for a predictable inertial confinement fusion at/beyond ignition

Fusion ignition has been successfully achieved at the National Ignition Facility, but the main obstacles of low-mode asymmetries, laser-plasma instabilities (LPIs), and hydrodynamic instabilities (HIs) still remain in the path toward a predictable yield for fusion ignition, especially at high gain. A recently proposed octahedral spherical Hohlraum, i.e., a spherical Hohlraum with six laser entrance holes of octahedral symmetry [Lan et al., Phys. Plasmas 21, 010704 (2014); Phys. Rev. Lett. 127, 245001 (2021)], was demonstrated to have the advantages of a naturally high radiation symmetry without any symmetry tuning technology and a high energy coupling efficiency from the drive laser to the capsule hotspot. In addition, a novel HDC–CH (here, HDC and CH refer to high density carbon and glow discharge plastic, respectively) capsule design was proposed to have the advantages in both low LPIs and low HIs by using two different ablators [Qiao and Lan, Phys. Rev. Lett. 126, 185001 (2021)]. For the first time, here we proposed a point design target composed of an octahedral spherical Hohlraum and an HDC–CH capsule to suppress the above-mentioned obstacles and presented the 2D simulation of the effect of symmetry and hydrodynamic instabilities on implosion performances. Our work provides a novel target design for a more predictable fusion ignition in experiment.

Alginate microgels encapsulation strategy of silver nanoparticles active against Candida albicans

Nanoparticles (NPs), offering high specific surface, are considered as the best potential anti-microbial agents for a wide range of medical nanotechnology. Among them, silver NPs (AgNPs) allow high biocidal activity. A design of ecological capsules is proposed where AgNPs of 22 nm in diameter are grafted on the surface of biobased nanocrystals obtained from cellulose (CNC) and chitin (ChiNC). These silver nanohybrids are dispersed in calcium-alginate microgels of 45–50 µm in diameter using microfluidic tools. Such double level of immobilization of AgNPs leads to highly stable carriers, prolongs shelf life and raises bioactivity, with a precise control of well dispersed AgNPs as determined by scanning transmission electron microscopy, UV-Vis spectroscopy and atomic absorption spectroscopy. Preliminary tests for antimicrobial activities of these new microgels have shown a significant inhibitory effect on Candida albicans, the most common fungal pathogen, responsible for thrush and vaginal yeast infections, for very low levels of silver.

Experimental and numerical investigations of an open-cell copper foam (OCCF)/phase change material (PCM) composite-based module for satellite avionics thermal management in a thermal vacuum chamber (TVC)

Small satellites' thermal control in the space environment is crucial. Phase change materials (PCM) are promising options for satellite thermal management in space thermal conditions. The current work provides an experimental and numerical investigation of a thermal control module (TCM) using an open-cell copper foam (OCCF)/PCM combination. The experimental tests were carried out in a thermal vacuum chamber (TVC), which simulated the vacuum space environment. The PCM thermal conductivity was boosted using OCCF and aluminium fins. The metallic parallel fins divided the heat sink into six cuboid cavities and were filled with PCM. Two samples with different pores per inch (PPI) of OCCF were adopted, one with 10 PPI and the other with 20 PPI. For the experimental work, the adopted PCM was SP 31. Two levels of heating loads were applied to the TCM: 10 W and 7 W. The numerical model was verified using the experimental work findings. The experimental work concluded that the PCM capsulation sealing is a dominant factor for successful capsule design under vacuum operation. The thermal conductivity enhancers (TCEs) remarkably improved the thermal management performance of the PCM. The case with PCM reported a reduction in the maximum temperature by about 43.67 % and 41.4 % at 7 W and 10 W, respectively, relative to the case without PCM. The PCM/fins combination could improve the PCM performance and mitigate the maximum temperature from 41.7 °C to 39.6 °C with a reduction percentage of 5 %. The OCCF reported better thermal performance than the metallic fins. The OCCF with 10 PPI decreased the PCM maximum temperature by 10.3 %. The OCCF with 20 PPI reported a reduction in the PCM maximum temperature by 13.8 % at 10 W heating power.

A standard capsule design for structural material testing in the Advanced Test Reactor

Nuclear materials testing is commonly completed in various material test and research reactors throughout the world, including the Advanced Test Reactor (ATR), but the current capsule design, analysis, and fabrication process can take years to complete. To decrease the costs and time associated with materials testing, a standard capsule has been designed which houses various specimen geometries and allows irradiation in virtually any ATR test position. The standard capsule features locking end caps which connect and lock together to form the capsule stack, eliminating the need for a basket and maximizing the quantity of specimens which are contained within the capsule. A customizable internal gas gap provides thermal resistance between the specimens and reactor coolant, making specimen temperatures from approximately 370 to 1000 K achievable. The flexibility of the capsule design allows experimenters to choose irradiation positions based off desired neutron flux, with typical fluences per cycle ranging from 8.8x1019 to 2.3x1021 n/cm2, depending on experiment position. This paper presents and discusses the standard capsule design and analysis.

Hybrid Polyelectrolyte Capsules Loaded with Gadolinium-Doped Cerium Oxide Nanoparticles as a Biocompatible MRI Agent for Theranostic Applications.

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nanostructures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires advanced imaging probes. This paper reports on a new design of MRI-visible LbL capsules, loaded with redox-active gadolinium-doped cerium oxide nanoparticles (CeGdO2-x NPs). CeGdO2-x NPs possess an ultrasmall size, high colloidal stability, and pronounced antioxidant properties. A comprehensive analysis of LbL capsules by TEM, SEM, LCSM, and EDX techniques was carried out. The research demonstrated a high level of biocompatibility and cellular uptake efficiency of CeGdO2-x-loaded capsules by cancer (human osteosarcoma and adenocarcinoma) cells and normal (human mesenchymal stem) cells. The LbL-based delivery platform can also be used for other imaging modalities and theranostic applications.

Irradiation experiments of titanium beryllide samples in the WWR-K reactor

This paper presents the results primary characterization of unirradiated titanium beryllide samples and neutron analysis of irradiation experiments of titanium beryllide Be12Ti samples in the WWR-K reactor. The XRD analysis of the samples was carried out. The surface morphology of the samples was studied using optical and electron microscopy. Two options of the irradiation capsule design are considered. The first design is designed for low-temperature irradiation, and the second design is for high-temperature irradiation. The effect of the capsule design on the neutron irradiation conditions of titanium beryllide samples is shown. The dynamics of tritium, helium-4 and helium-3 generation in samples is given. The values of the specific energy release of samples and structural materials of the capsule are calculated. The rate of displacements per atom in the irradiated material is estimated.

Monte Carlo-based optimization of glioma capsule design for enhanced brachytherapy

The use of radiotherapy in tumor treatment has become increasingly prominent and has emerged as one of the main tools for treating malignant tumors. Current radiation therapy for glioma employs 125I seeds for brachytherapy, which cannot be combined with radiotherapy and chemotherapy. To address this limitation, this paper proposes a dual-microcavity capsule structure that integrates radiotherapy and chemotherapy. The Monte Carlo simulation method is used to simulate the structure of the dual-microcavity capsule with a 125I liquid radioactive source. Based on the simulation results, two kinds of dual-microcavity capsule structures are optimized, and the optimized dual-microcavity capsule structure is obtained. Finally, the dosimetric parameters of the two optimized dual-microcavity capsule structures are analyzed and compared with those of other 125I seeds. The optimization tests show that the improved dual-capsule dual-microcavity structure is more effective than the single-capsule dual-microcavity structure. At an activity of 5 mCi, the average absorbed dose rate is 71.2 cGy/h in the center of the optimized dual-capsule dual-microcavity structure and 45.8 cGy/h in the center of the optimized single-capsule dual-microcavity structure. Although the radial dose function and anisotropy function exhibite variations from the data of other 125I seeds, they are generally similar. The absorbed dose rate decreases exponentially with increasing distance from the center of the capsule, which can reduce the damage to the surrounding tissues and organs while increasing the dose. The capsule structure has a better irradiation effect than conventional 125I seeds and can accomplish long-term, stable, low-dose continuous irradiation to form local high-dose radiation therapy for glioma.

Thermo Structural Integrity of a Closure Assembly for The Base Region of a Re-Entry Module

Base heating is an important phenomenon in the design of re-entry capsules. The nature of reverse flow in the base region is largely decided by the conditions prevailing at the end of the fore body. For configuration like the re-entry module, the reverse flow is found to be supersonic near the base. It is therefore necessary to protect the base region as well as the internal components from base heating.
 Suitable Thermal Protection System (TPS) of minimum mass that will protect the base thermally is to be designed for the base heating levels during re-entry. Low density ablative is selected as the TPS material.
 The base region of the re-entry module consists of a closure assembly made up of structural elements which are thermally protected. The structural elements and TPS have different thermo-physical properties. It is necessary to qualify the closure assembly for re-entry loads. However, qualification of closure assembly is a challenging job as there is no facility in the world which can simulate all the time varying flight parameters simultaneously. Hence to study the integrity of the closure assembly during re-entry, detailed temperature mapping of closure assembly was carried out.
 Thermal mapping of the closure assembly was carried out considering both axisymmetric and three-dimensional model using finite element package and the results are compared. Maximum temperatures attained at different locations of the assembly are discussed. Temperature distribution of the closure assembly at critical instants of flight was estimated. Thermo-structural analysis carried out showed the adequacy of the design, which was subsequently demonstrated by a successful re-entry flight.

Effects of Internal Boundary Layers and Sensitivity on Frequency Response of Shells of Revolution

New applications introduced capsule designs with features that have not been fully analysed in the literature. In this study, thin shells of revolution are used to model drug delivery capsules both with closed and open designs including perforations. The effects of internal boundary layers and sensitivity on frequency response are discussed in the special case with symmetric concentrated load. The simulations are carried out using high-order finite element method and the frequency response is computed with a very accurate low-rank approximation. Due to the propagation of the singularities induced by the concentrated loads, the most energetic responses do not necessarily include a pinch-through at the point of action. In sensitive configurations, the presence of regions with elliptic curvature leads to strong oscillations at lower frequencies. The amplitudes of these oscillations decay as the frequencies increase. For efficient and reliable analysis of such structures, it is necessary to understand the intricate interplay of loading types and geometry, including the effects of the chosen shell models.

Design of Tailor-Made Biopolymer-Based Capsules for Biological Application by Combining Porous Particles and Polysaccharide Assembly.

Various approaches have been described in the literature to demonstrate the possibility of designing biopolymer particles with well-defined characteristics, such as size, chemical composition or mechanical properties. From a biological point of view, the properties of particle have been related to their biodistribution and bioavailability. Among the reported core-shell nanoparticles, biopolymer-based capsules can be used as a versatile platform for drug delivery purposes. Among the known biopolymers, the present review focuses on polysaccharide-based capsules. We only report on biopolyelectrolyte capsules fabricated by combining porous particles as a template and using the layer-by-layer technique. The review focuses on the major steps of the capsule design, i.e., the fabrication and subsequent use of the sacrificial porous template, multilayer coating with polysaccharides, the removal of the porous template to obtain the capsules, capsule characterisation and the application of capsules in the biomedical field. In the last part, selected examples are presented to evidence the major benefits of using polysaccharide-based capsules for biological purposes.

Construction of Multifunctional Composites for Electromagnetic Shielding and Infrared Stealth Based on Magnetic Phase Change Capsules and Silicone Rubber Foam

AbstractFunctionalization of phase change capsules is recognized as one of the promising technologies to improve energy efficiency and promote their versatile application. Herein, a new magnetic phase change capsule (NiFe2O4‐encapsulated phase change material (EPCM)) composed of paraffin wax core and SiO2‐NiFe2O4 double‐layer shell is designed. The prepared NiFe2O4‐EPCMs possess sensitive magnetic response, excellent thermal management performance, and enhanced thermal stability. In particular, the representative NiFe2O4‐EPCM‐4 has the highest saturation magnetization (8.41 emu · g−1) and high enthalpy of 131.2 J · g−1. Subsequently, NiFe2O4‐EPCM‐4 is introduced into silicone rubber foam (SRF) matrix and magnetic composite SRFs (MSRFs) are prepared. The latent heat of MSRF‐3 containing 30% NiFe2O4‐EPCM‐4 can reach 28.9 J g−1 and there is almost no change even after 200 cycles. In comparison with pure SRF, the tensile strength and compressive strength of MSRF‐3 are increased by 167.7% and 941.8%, respectively. Importantly, the electromagnetic interference shielding effectiveness of MSRF‐3 is significantly improved from 15.9 to 30.6 dB. Besides, the MSR‐3 can achieve an intriguing infrared stealth function for targets both in human body temperature and high temperature environment. Therefore, this work might stimulate people's interest and inspiration in the design and preparation of multifunctional phase change capsules.

Design and assembly of biodegradable capsules based on alginate hydrogel composite for the encapsulation of blue dye

The encapsulation of bluing agents in biodegradable polymeric capsules is an emerging option in laundry detergents sector to substitute formaldehyde-based polymers, because they are non-biodegradable, carcinogenic and toxic. In this work, we present for the first time the successful encapsulation of a blue dye in biodegradable capsules which shell was formed by an alginate hydrogel and a polyethylene glycol network. Different types of capsules were synthesized (addition or not of the diacrylate monomer) and irradiation of the crosslinking solution at different times. Furthermore, a deep characterization of each type of capsules was performed (chemical and morphological characterization, assessment of their mechanical and thermal properties, evaluation of their biodegradability), noting that the incorporation of the diacrylate monomer (PEGDMA) and the two different irradiation times selected substantially affected the final properties of the capsules. The obtained results will serve to comprehend how the dye can be released from the capsules.

Hyperglycemic Conditions Enhance the Mechanosensitivity of Proinflammatory RAW264.7 Macrophages.

Macrophages are a primary contributor to the orchestration and severity of the foreign body response. As phagocytes and antigen-presenting cells, macrophages engage foreign objects, producing chemokines, degrading enzymes, and proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Encapsulated islet transplantation (EIT) is a return of function therapy in which donor insulin-secreting cells are encased in a biomaterial and implanted into a diabetic patient to regulate blood glucose levels. However, the foreign body response by macrophages to the encapsulated islet allograft may cause rejection. Recent studies have shown that substrate stiffness affects macrophage activity, which can inform EIT capsule design. However, due to the dysregulation of glucose maintenance in diabetic patients, varying from normoglycemic to hypoglycemic or hyperglycemic conditions, it is imperative to determine if glucose dysregulation affects macrophage mechanosensitivity to EIT biomaterials. This study explores the relationship between glucose metabolism and mechanosensitivity and the ultimate impact on proinflammatory macrophage function in static hyperglycemic and normoglycemic conditions. Using a 2-dimensional (2D) polyacrylamide model of 3-order magnitude in stiffness, 2, 15, and 274 kPa Young's moduli, the effect of glycemic condition on the mechanosensitive characteristics of unstimulated and proinflammatory RAW264.7 macrophage function in vitro using lipopolysaccharide (LPS) was examined. Hyperglycemic conditions were found to impact macrophage response to substrate stiffness significantly. Notably, TNF-α secretion was significantly reduced as substrate stiffness increased in LPS-stimulated hyperglycemic conditions, whereas normoglycemic macrophages held similar secretion across all stiffnesses. Stiffness-influenced differences in cytokine secretion were also induced in IL-6 secretion by hyperglycemic conditions. Hyperglycemic conditions promoted a biphasic trend in IL-6 cytokine secretion and gene expression by proinflammatory macrophages with significantly decreased production when cultured on 15 kPa compared to production on 2 and 274 kPa. Although hyperglycemic conditions drastically increased IL-10 secretion, stiffness-influenced differences were not shown when compared to the same glycemic condition. Furthermore, under LPS stimulation, lactate secretion had an inverse relationship to TNF-α secretion. However, no significant stiffness-influenced difference was demonstrated in glucose transporter 1 (GLUT1) expression, glucose uptake, or GAPDH. These findings suggest that hyperglycemic conditions enhance the mechanosensitivity of proinflammatory macrophages and should be explored further. Impact statement The work presented increases our understanding of the effect of glycemic condition on macrophage mechanosensitivity related to substrate stiffness. This has ramifications on the design of material-based therapies, such as encapsulated islet transplantation, for type 1 diabetic patients who experience glycemic dysregulation.

Design of millimeter-scale microwave-induced capsules and their non-instantaneous release

In recent years, many studies have been carried out on the release system induced by the microwave signal, featured with great thermal efficiency and high penetration. However, studies on microwave responsive system on millimeter length scale are limited, which is of great importance due to its high loading capacity and widespread application. In this study, novel microwave-induced capsules on millimeter length scale with responsiveness in water-free environment, consisting of paraffin shell and the supportive skeleton fibers were designed and prepared. The detailed microwave-induced releasing behaviors, together with the morphology, loading capacity of capsules were systematically investigated. Non-instantaneous releasing behavior consisted of microwave heating, shell melting and core releasing was observed, and was supported by numerical simulations. The key role of paraffin shell with different thickness was confirmed in the kinetics of releasing. The release profile can be well described by a two-segment model, which includes zero-order model and cumulative distribution functions, corresponding to diffusion controlled and shell-melting controlled releasing processes, respectively.

A Case for Material Stiffness as a Design Parameter in Encapsulated Islet Transplantation.

Diabetes is a disease that plagues over 463 million people globally. Approximately 40 million of these patients have type 1 diabetes mellitus (T1DM), and the global incidence is increasing by up to 5% per year. T1DM is where the body's immune system attacks the pancreas, specifically the pancreatic beta cells, with antibodies to prevent insulin production. Although current treatments such as exogenous insulin injections have been successful, exorbitant insulin costs and meticulous administration present the need for alternative long-term solutions to glucose dysregulation caused by diabetes. Encapsulated islet transplantation (EIT) is a tissue-engineered solution to diabetes. Donor islets are encapsulated in a semipermeable hydrogel, allowing the diffusion of oxygen, glucose, and insulin but preventing leukocyte infiltration and antibody access to the transplanted cells. Although successful in small animal models, EIT is still far from commercial use owing to necessary long-term systemic immunosuppressants and consistent immune rejection. Most published research has focused on tailoring the characteristics of the capsule material to promote clinical viability. However, most studies have been limited in scope to biochemical changes. Current mechanobiology studies on the effect of substrate stiffness on the function of leukocytes, especially macrophages-primary foreign body response (FBR) orchestrators, show promise in tailoring a favorable response to tissue-engineered therapies such as EIT. In this review, we explore strategies to improve the clinical viability of EIT. A brief overview of the immune system, the FBR, and current biochemical approaches will be elucidated throughout this exploration. Furthermore, an argument for using substrate stiffness as a capsule design parameter to increase EIT efficacy and clinical viability will be posed.

Design Optimization of Hot Isostatic Pressing Capsules

Power metallurgy hot isostatic pressing (PM-HIP) is a manufacturing technique capable of producing net shape or near-net shape components with complicated geometries from materials that are difficult to melt and cast, mechanically deform or weld. However, the process and soundness of the outcome are extremely sensitive to the geometric design of the capsule (also known as the die or can) that is used in the process. The capsule design for each new component involves several trial–error iterations to achieve the desired geometry and shape of the component. For each iteration, costly HIP experiments need to be conducted and new capsules need be manufactured with small modifications. In this study, a robust finite element analysis (FEA) model of the HIP process is developed, then wrapped in a multi-objective genetic algorithm (MOGA) optimization framework to obtain the optimal pre-HIP capsule design, which yields the desired post-HIP component geometry in one HIP run. The FEA-based optimization algorithm is validated by HIP experiments, showing excellent agreement between the experiment and the model.