Cryogenic Behavior Research Articles

Cryogenic mechanical behavior of 5000- and 6000-series aluminum alloys: Issues on application to offshore plants

The mechanical behavior of aluminum alloys was investigated in terms of four aspects: temperature, strain rate, material type, and fracture shape. The candidate materials were 5000- and 6000-series alloys. The material characteristics were investigated and summarized as a function of low temperature (110–293K) and quasi-static strain rate (10−4 and 10−2s−1). The results confirmed that the strength and ductility of aluminum alloys improved with a decrease in the temperature. The aluminum alloys showed a strain rate effect only in terms of the ductility of the 5000-series alloys. In addition, fractography analyses were performed on the fracture specimens to explain the material behavior at cryogenic temperatures.

Effect of dimethylpolysiloxane liquid on the cryogenic tensile strength and thermal contraction behavior of epoxy resins

Dimethylpolysiloxane liquid was blended with diglycidyl ether of bisphenol-A epoxy resin including anhydride curing agent to improve the tensile strength of the epoxy resin at 77K without any increase in its coefficient of thermal expansion (CTE). A bifunctional polymer, silicone-modified epoxy resin (SME), was also added to the mixture as a compatibilizer. The results of UV transmittance for the blend resin showed that the incorporation of the SME could stabilize effectively spherical domains of the siloxane liquid which was immiscible with the epoxy matrix. The tensile strengths of the blend resins at both room temperature and 77K were measured and SEM analysis for the fractured cross sections was carried out to verify the toughening behavior of the liquid droplets. The results indicated that even small amount of addition of the siloxane liquid (0.05 phr) coupled with SME (20 phr) could enhance the tensile strength at 77K by 77.6% compared to that of the neat epoxy resin. This improvement is attributed to the fact that the solid and s droplets can disperse the localized stress and interrupt the crack propagation by cavitation mechanism followed by multiple generation of numerous micro-deformation. From the CTE measurement, the siloxane liquid has no influence on the thermal contraction behavior of the blend resin.

Cryogenic fracture of cracked piezoelectric ceramics in three-point bending under electric fields

This paper studies analytically and experimentally the cryogenic static fatigue behavior of cracked piezoelectric ceramics under electric fields. The crack was created normal to the poling direction. Static fatigue tests were carried out in three-point bending with the single-edge precracked-beam specimens at room temperature and liquid nitrogen temperature (77 K), and times-to-failure under different mechanical loads and electric fields were obtained. Plane strain finite element analysis using temperature-dependent material properties of piezoelectric ceramics was also performed, and the energy release rate for the permeable crack model was calculated. The effects of electric field and temperature on the energy release rate versus lifetime curve are discussed.

Fatigue delamination growth in woven glass/epoxy composite laminates under mixed-mode II/III loading conditions at cryogenic temperatures

We investigate the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates under mixed-mode II/III fatigue loading. Fatigue delamination tests were conducted with six-point bending plate (6PBP) specimens at room temperature, liquid nitrogen temperature (77K) and liquid helium temperature (4K), and the delamination growth rate data for various mixed-mode ratios of Modes II and III were obtained. The energy release rate was evaluated using the three-dimensional finite element method. In addition, the fatigue delamination growth mechanisms were characterized by scanning electron microscopic observations of the specimen fracture surfaces.

Mechanical properties and crystallization behavior of hydroxyapatite/poly(butylenes succinate) composites

Biodegradable synthetic polymers have attracted much attention nowadays, and more and more researches have been done on biodegradable polymers due to their excellent mechanical properties, biocompatibility, and biodegradability. In this work, hydroxyapatite (HA) particles were melt-mixing with poly (butylenes succinate) (PBS) to prepare the material, which could be used in the biomedical industry. To develop high-performance PBS for cryogenic engineering applications, it is necessary to investigate the cryogenic mechanical properties and crystallization behavior of HA/PBS composites. Cryogenic mechanical behaviors of the composites were studied in terms of tensile and impact strength at the glass transition temperature (-30°C) and compared to their corresponding behaviors at room temperature. With the increase of HA content, the crystallization of HA/PBS composites decreased and crystallization onset temperature shifted to a lower temperature. The diameter of spherulites increased at first and decreased with a further HA content. At the same time, the crystallization rate became slow when the HA content was no more than 15wt% and increased when HA content reached 20wt%. In all, the results we obtained demonstrate that HA/PBS composites reveal a better tensile strength at -30°C in contrast to the strength at room temperature. HA particles with different amount affect the crystallization of PBS in different ways.

Controllability of cryogenic Mode I delamination behavior in woven fabric composites using piezoelectric actuators

This paper investigates experimentally and numerically the delamination behavior in woven glass fiber reinforced polymer (GFRP) composite laminates with surface-bonded piezoelectric ceramic actuators under Mode I loading at cryogenic temperatures. The piezoelectric actuators were used to control the delamination behavior in a composite double cantilever beam (DCB) specimen, and tests were performed at liquid nitrogen temperature (77K). The finite element analysis of the DCB specimen with piezoelectric actuators was also carried out using temperature-dependent material properties of both the woven GFRP laminates and the piezoelectric ceramics, and the numerical predictions were compared with the experimental data. The dependence of the Mode I delamination behavior on the applied electric fields and the temperature was examined based on the experimental and numerical results, and the feasibility of piezoelectric control of cryogenic delamination behavior in composite laminates was demonstrated.

OS0306 電場下におけるき裂を有する圧電セラミックスの3点曲げによる極低温破壊

This paper investigates theoretically and experimentally the cryogenic fracture behavior of cracked piezoelectric ceramics under electric fields. Fracture tests were performed in three-point bending with the single-edge precracked-beam (SEPB) specimens at room temperature (RT) and liquid nitrogen temperature (77 K), and the fracture loads under electric fields were obtained. Plane strain finite element analysis was also carried out using temperature-dependent material properties of the piezoelectric ceramics, and the dependence of the energy release rate on the electric field and temperature was discussed. In addition, possible mechanisms for cryogenic fracture were examined by scanning electron microscopy (SEM).

Integrated computational study of ultra-high heat flux cooling using cryogenic micro-solid nitrogen spray

A new type of ultra-high heat flux cooling system using the atomized spray of cryogenic micro-solid nitrogen (SN2) particles produced by a superadiabatic two-fluid nozzle was developed and numerically investigated for application to next generation super computer processor thermal management. The fundamental characteristics of heat transfer and cooling performance of micro-solid nitrogen particulate spray impinging on a heated substrate were numerically investigated and experimentally measured by a new type of integrated computational–experimental technique. The employed Computational Fluid Dynamics (CFD) analysis based on the Euler–Lagrange model is focused on the cryogenic spray behavior of atomized particulate micro-solid nitrogen and also on its ultra-high heat flux cooling characteristics. Based on the numerically predicted performance, a new type of cryogenic spray cooling technique for application to a ultra-high heat power density device was developed. In the present integrated computation, it is clarified that the cryogenic micro-solid spray cooling characteristics are affected by several factors of the heat transfer process of micro-solid spray which impinges on heated surface as well as by atomization behavior of micro-solid particles. When micro-SN2 spraying cooling was used, an ultra-high cooling heat flux level was achieved during operation, a better cooling performance than that with liquid nitrogen (LN2) spray cooling. As micro-SN2 cooling has the advantage of direct latent heat transport which avoids the film boiling state, the ultra-short time scale heat transfer in a thin boundary layer is more possible than in LN2 spray. The present numerical prediction of the micro-SN2 spray cooling heat flux profile can reasonably reproduce the measurement results of cooling wall heat flux profiles. The application of micro-solid spray as a refrigerant for next generation computer processors is anticipated, and its ultra-high heat flux technology is expected to result in an extensive improvement in the effective cooling performance of large scale supercomputer systems.

Cryogenic Ka-Band 180$^{\circ}$ Phase Switch Based on Schottky Diodes

A Ka-band hybrid 0/180 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> phase switch working at cryogenic temperature is presented. The circuit is designed on an alumina substrate using uniplanar hybrid technology, combining air-bridged coplanar waveguides and slotlines. Schottky diodes are used as switching elements, taking advantage of their cryogenic behavior, with low equivalent series resistance and low capacitance. Cryogenic performance at 15 K shows a phase difference response of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$177 \pm 2^{\circ}$</tex></formula> , average insertion losses of 1 dB and amplitude imbalance of less than 0.2 dB between states in the frequency range from 24 to 37 GHz (40% relative bandwidth) with a low-power consumption of 10.5 mW. The low insertion loss and small phase error make the designed phase switch suitable to be used on radioastronomy receivers (QUIJOTE experiment 26–36 GHz band) minimizing the total system noise temperature.

Er3+ in Sc2O3 and Y2O3: Spectroscopy to elucidate laser behavior

Er:Sc2O3 exhibits spectroscopic properties that give surprising cryogenic laser behavior (particularly broad zero-line absorption, and a switch to a shorter laser wavelength for temperatures above 110K). We find that spectroscopic comparison of this material with Er:Y2O3 clarifies the subtle features responsible for this laser behavior.

Research on cryogenic behaviors of low noise amplifier with build-in PIN diode limiter

In this article we elucidate the design and fabrication of a P-band cryogenic low noise amplifier (CLNA) with built-in limiter circuit, and further studied the characteristics of PIN diode limiter at different temperature. Measurements at 75 K shows the P-band CLNA with build-in limiter has a good performance with noise figure lower than 0.5 dB, the input and output voltage standing wave ratio (VSWR) less than 1.5 and input 1 dB power compression point −4 dBm within the band width 300 MHz. The variation of the gain within ±0.1 dB under the impact of 20 dBm input power level signals. In addition, the maximum allowed input power of the CLNA has increased from 13 dBm to 22 dBm.

Operational performance of EAST cryogenic system and analysis of it's upgrading

Since the first commissioning in February 2005, EAST cryogenic system was cooled down and warmed up for seven physics experimental campaigns. The operational performance of the cryogenic system, and heat loads released on different operational modes, together with cryogenic behaviors on magnets are presented in this paper. All of the thirteen pairs of current leads (CLs) in EAST tokamak have been upgraded to high temperature superconductor (HTS) current leads, so the liquefaction requirement for the refrigerator was greatly reduced and operational mode is quite different from the original optimization mode. In addition, when the physics experiments progress steadily, the requirements of the refrigeration are becoming higher. Furthermore, some components need to be replaced, because of low efficiencies or low stability. So the cryogenic system needs to be analyzed for upgrading. This paper presents the preliminary analysis.

Cryogenic mechanical behaviors of carbon nanotube reinforced composites based on modified epoxy by poly(ethersulfone)

Cryogenic mechanical properties are important parameters for epoxy resins used in cryogenic engineering areas. In this study, multi-walled carbon nanotubes (MWCNTs) were employed to reinforce diglycidyl ether of bisphenol F (DGBEF)/diethyl toluene diamine (DETD) epoxy system modified by poly(ethersulfone) (PES) for enhancing the cryogenic mechanical properties. The epoxy system was properly modified by PES in our previous work and the optimized formulation of the epoxy system was reinforced by MWCNTs in the present work. The results show that the tensile strength and Young’s modulus at 77 K were enhanced by 57.9% and 10.1%, respectively. The reported decrease in the previous work of the Young’s modulus of the modified epoxy system due to the introduction of flexible PES is offset by the increase of the modulus due to the introduction of MWCNTs. Meanwhile, the fracture toughness ( K IC) at 77 K was improved by about 13.5% compared to that of the PES modified epoxy matrix when the 0.5 wt.% MWCNT content was introduced. These interesting results imply that the simultaneous usage of PES and MWCNTs in a brittle epoxy resin is a promising approach for efficiently modifying and reinforcing epoxy resins for cryogenic engineering applications.

Cryogenic fracture behavior of metastable austenitic stainless steel in a high magnetic field

We study the effect of magnetic field on the fracture behavior of the metastable austenitic stainless steels at cryogenic temperatures. Elastic-plastic fracture toughness tests were performed on compact tension specimens in liquid helium at 4 K with and without a magnetic field, and the effect of magnetic field on the cryogenic fracture toughness was discussed. Quantitative phase analysis was also done by magnetic method, and the fracture surfaces were examined by scanning electron microscopy to correlate with the fracture properties.

Numerical and Experimental Analysis of a Fluidized Bed for IFE Target Layering

A fluidized bed is being studied as a very promising method for mass production of IFE targets. Large beds could be filled with many targets to provide large-scale production, while a near-isothermal environment could be maintained in principle around each target (as required for smooth layering to meet the physics requirements on the ice characteristics) through the random movement and spin of individual targets within a precisely controlled gas stream. Concerns exist, however, including the effect of unbalanced spheres on the bed behavior and ultimately on the target thermal environment, as well as the possible damage of the target surface (in particular the thin high-Z coating).This effort includes developing a numerical fluidized bed model and conducting laboratory-scale companion experiments to help understand the cryogenic fluidized bed behavior. Key challenges in developing the model include the relative size of the spherical targets (˜4.0 mm) compared to the size of the prototypic fluidized bed container (˜26 mm in diameter), which is much larger than those found in conventional fluidized bed models and which calls for a different modeling approach. In addition, the behavior of unbalanced targets, which results from the initial D-T filling and freezing in the target production process, needs to be accounted for.This paper summarizes the development of this model, including the validation performed by comparing the model results to controlled lab-scale experiments. The goal is to use the model for parametric analysis to help determine the most promising state of operation to deliver large quantities of uniformly layered target shells. This will provide key pre-operational input to the prototypical experimental set-up, which is currently being built and which includes a high-pressure deuterium filling station in addition to the cryogenic fluidized bed operating at temperatures around 18 K.

Mode III fatigue delamination growth of glass fiber reinforced polymer woven laminates at cryogenic temperatures

This paper investigates the cryogenic fatigue delamination behavior of glass fiber reinforced polymer woven laminates under Mode III loading. Fatigue delamination tests were conducted using split cantilever beam specimens at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K). A finite element analysis was also employed to calculate the energy release rate. The temperature dependence of the fatigue delamination growth rate vs. energy release rate range is discussed. Fracture surfaces were examined by scanning electron microscopy to identify the delamination mechanisms under fatigue loading. The important conclusion we reach is that the Mode III fatigue delamination growth rates of woven laminates at cryogenic temperatures are lower than that at room temperature.

Delamination growth mechanisms in woven glass fiber reinforced polymer composites under Mode II fatigue loading at cryogenic temperatures

The purpose of this research is to characterize the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates subjected to Mode II fatigue loading. Mode II fatigue delamination tests were performed at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K) using the four-point bend end-notched flexure (4ENF) test method, and the delamination growth rate data for the woven GFRP laminates were obtained. The energy release rate range was determined by the finite element method. Microscopic examinations of the specimen sections and fracture surfaces were also carried out. The present results are discussed to obtain an understanding of the fatigue delamination growth mechanisms in the woven GFRP laminates under Mode II loading at cryogenic temperatures.

Thermal Simulations of the Intermediate Step Laser Megajoule Cryogenic Target (Parametric Study)

This paper presents a detailed assessment of the intermediate step design Laser Megajoule cryogenic target thermal behavior. Several simulations were carried out with a computational fluid dynamics code named FLUENT in order to better understand the effect of different parameters on this new design.

OS0417 極低温における織物ガラス繊維強化ポリマーコンポジットのモードII疲労はく離進展メカニズム(先端材料システムの力学とメゾスケールモデリング,オーガナイズドセッション)

The purpose of this research is to characterize the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates subjected to Mode II fatigue loading. Mode II fatigue delamination tests were performed at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K) using the four-point bend end-notched flexure (4ENF) test method, and the delamination growth rate data for the woven GFRP laminates were obtained. The energy release rate range was determined by the finite element method. Microscopic examinations of the specimen sections and fracture surfaces were also carried out The present results are discussed to obtain an understanding of the fatigue delamination growth mechanisms in the woven GFRP laminates under Mode II loading at cryogenic temperatures.

Hydrofoil Cavitation Under Strong Thermodynamic Effect

Cavitation was studied for a NACA0015 hydrofoil using a material that simulates cryogenic behavior. Several angles of attack and flow speeds up to 8.6m∕s were tested. The material used, 2-trifluoromethyl-1,1,1,2,4,4,5,5,5-nonafluoro-3-pentanone, hereafter referred to as fluoroketone, exhibits a strong thermodynamic effect even under ambient conditions. Static pressures were measured at seven chordwise locations along the centerline of the hydrofoil suction side and on the test section wall immediately upstream of the hydrofoil. Frequency analysis of the test section static pressure showed that the amplitude of the oscillations increased as the tunnel speed increased. A gradual transition corresponding to the Type II-I sheet cavitation transition observed in water was found to occur near σ∕2α=5 with Strouhal numbers based on chord dropping from 0.5 to 0.1 as the cavitation number was reduced. Flash-exposure high-speed imaging showed the cavity covering a larger portion of the chord for a given cavitation number than in cold water. The bubbles appeared significantly smaller in the current study and the pressure data showed increasing rather than constant static pressure in the downstream direction in the cavitating region, in line with observations made in literature for other geometries with fluids exhibiting strong thermodynamic effect.