Statistical fatigue strength evaluation and inelastic deformation generated during static and cyclic loadings in Ce-TZP/alumina nanocomposite: part 2 – in water environment

The statistical fatigue strength evaluations in water of an intragranular type Ce-TZP/Al₂O₃ nanocomposite (Ce-TZP/A-N) were investigated in comparison to 3Y-TZP. The isothermal t-m transformation which causes low temperature aging degradation (LTAD) did not occur during fatigue tests for both materials. The strength degradations under static and cyclic loadings of Ce-TZP were fairly small compared to those of 3Y-TZP. The life shortening in water of 3Y-TZP was slight, and Ce-TZP/A-N maintained comparable fatigue lives found in air. Large inelastic deformations (converted strain = 0.06–0.23%) were observed in the non-failure fatigued specimens after static and cyclic loadings. The amount of inelastic deformations and relevant transformed monoclinic contents in water were smaller than those in air at equivalent stress level. In contrast, the volume fractions of the monoclinic phase in water were slightly higher than those in air at equivalent strain level. For 3Y-TZP, no inelastic deformation was identified.     

Experimental study on control fins of a small flying vehicle using piezo-composite actuators

A camber morphing control fin design and an all-moving control fin design using piezo-composite unimorph actuators are presented in this paper. The control fin of a small flying object is usually actuated using a servo motor system with an electromagnetic motor. Much research has been conducted to solve the structural complexity of servo actuation systems to convert the rotation of a servo motor to a linear actuation motion. To simplify this structural complexity, several types of smart actuators have been developed, such as bimorph or unimorph actuators with piezoelectric material layers and shape memory alloy actuators. In this study, a camber morphing type control fin and an all-moving type control fin actuated using piezo-composite actuators are designed to evaluate their ability to simplify the structural complexity of the gear transmission and electromagnetic servo motor system or hydraulic actuator system. Within the skin of the control fin, a piezo-composite actuator is mounted and the other end inserted in a slot of the control fin. As the piezo-composite actuator is excited by an electric field, the pitch angle of the control fin is changed. Experimental testing for the pitch rotation angle of a control fin in a 450 V electric field showed the deflection angle of the camber morphing control fin was 1.4° and the rotational angle of the all-moving control fin was 5.4°, which is obtained from the rotation angle magnification linkage structural system.     

铁路路基沉降变形问题的控制方法研究

指出铁路路基在自重力和列车荷载力的作用下,容易产生施工后的沉降变形问题,对铁路路基沉降问题原因进行了分析,并提出控制铁路路基沉降变形的具体方法,以便作为铁路建设工程施工的借鉴参考资料。     

消除汽缸变形 提高机组热效率

针对某热电厂150MW热电联产机组存在的汽轮机高中压内缸变形严重的问题，分析了其对汽轮机缸效、热耗带来的影响，通过与修造厂合作，现场自主处理了汽缸变形严重的缺陷，提高了高中压缸的缸效，为企业的节能降耗取得了明显的成效。     

The sticking behavior of an ultra purified ferritic stainless steel during hot strip rolling

During hot rolling of ferritic stainless steels (FSSs), sticking can cause severe surface defects both on work rolls and strips especially for ultra purified FSSs with the total amount of carbon and nitrogen being less than 150 ppm. In the present paper, high temperature oxidization behavior of the ultra purified FSSs was characterized. A new experimental method was invented to simulate the sticking behavior of ultra purified 21%Cr FSS, by which specially designed specimens were hot compressed with different processing parameters to simulate hot strip rolling process. The specimens were surface conditioned prior to the simulation test, either by mechanically polishing or by pre-oxidization to form oxide scales with certain thickness. Observation on the cross-section of sticky regions indicated that cracks had been formed by cyclic heating and cooling during hot deformation had been acting as nucleation sites for sticking particles. The results indicated that oxide scale could avoid the direct contact between roll surfaces and rolled materials to help reducing the sticking occurrence. The temperature region for easy sticking occurrence in the ultra purified 21%Cr FSS has been measured to be from 900 to 1100 °C, which is enlarged as compared to other plain FSSs. The tendency for sticking occurrence decreased with increasing strain rate and decreasing the hammer or work roll surface roughness.     

A Model Coupling Method for Shape Prediction

 The shape of strip is calculated by iterative method which combines strip plastic deformation model with rolls elastic deformation model through their calculation results, which can be called results coupling method. Because the shape and rolling force distribution are very sensitive to strip thickness transverse distribution′s variation, the iterative course is rather unstable and sometimes convergence cannot be achieved. In addition, the calculating speed of results coupling method is low, which restricts its usable range. To solve the problem, a new model coupling method is developed, which takes the force distribution between rolls, rolling force distribution and strip′s exit transverse displacement distribution as basic unknowns, and integrates strip plastic deformation model and rolls elastic deformation model as a unified linear equations through their internal relation, so the iterative calculation between the strip plastic deformation model and rolls elastic deformation model can be avoided. To prove the effectiveness of the model coupling method, two examples are calculated by results coupling method and model coupling method respectively. The results of front tension stress, back tension stress, strip′s exit gauge, the force between rolls and rolling force distribution calculated by model coupling method coincide very well with results coupling method. However the calculation course of model coupling method is more steady than results coupling method, and its calculating speed is about ten times as much as the maximal speed of results coupling method, which validates its practicability and reliability.     

Effect of element Ru on microstructure and creep behaviour of single crystal nickel-based superalloy

By means of creep property measurement and microstructure observation, the influence of element Ru on the microstructure and creep behaviour of single crystal nickel-based superalloy is investigated. The results show that the plate-like μ phase is precipitated along {111} plane of the Ru-free alloy during thermal exposure at 1080°C and creep at 980°C. And the precipitation of μ phase in the alloy with 6(wt)%Mo and 6(wt)%W may be restrained by adding 2% Ru element. Compared to Ru-free alloy, the creep life of the 2% Ru single crystal alloy at 980°C200 MPa increases form 123 h to 333h. Compared to the 2% Ru alloy, the precipitated plate-like μ phase in the Ru-free alloy may promote the initiation and propagation of cracks along the γ matrix up to fracture, which is thought to be the main reason of the alloy having a lower creep resistances and shorter lifetime.     

Developing a four‐layer system rutting model in highway

Abstract

A four‐layer rutting model was developed to account for material property changes in the progression of accumulated compressive plastic strains in all roadway layers on the basis of traffic passing in this study. This paper demonstrates that incorporating the mechanistic‐empirical approach in the prediction of rutting provides value information on the contribution of each layer to rutting in flexible pavements.     

Impact of Serum Chemerin Levels on Liver Functional Reserves and Platelet Counts in Patients with Hepatocellular Carcinoma

Obesity-related metabolic abnormalities, including adipokine imbalance and chronic inflammation, are involved in liver carcinogenesis. Chemerin, a novel adipokine, plays a critical role in adipogenesis, energy metabolism, and inflammation. We evaluated the impact of serum chemerin levels on liver functional reserves in hepatocellular carcinoma (HCC) patients and on the recurrence and prognosis of HCC. This study included 44 patients with any stage of HCC who underwent curative treatment at Gifu Municipal Hospital (Gifu, Japan) between 2006 and 2007. Recurrence-free survival and overall survival were estimated using the Kaplan-Meier method. Serum albumin levels (Pearson’s correlation coefficient; r = 0.3110, p = 0.0399), platelet counts (r = 0.4159, p = 0.0050), and prothrombin times (r = 0.3775, p = 0.0115) were significantly correlated with serum chemerin levels in patients with HCC, and they were inversely correlated with Child-Pugh scores (r = −0.3732, p = 0.0126), serum alanine aminotransferase levels (r = −0.3864, p = 0.0105), and total bilirubin levels (r = −0.4023, p = 0.0068). Among these variables, a multiple comparison test identified that platelet counts and total bilirubin levels were associated with serum chemerin levels (p < 0.0083). No significant correlation was found between serum chemerin levels and recurrence-free survival (p = 0.3691) or overall survival (p = 0.7916). In HCC patients, serum chemerin concentrations were correlated with liver functional reserves and platelet counts, but not with recurrence or prognosis.     

Thermal properties of duck fatty liver (foie gras) products

Thermal properties of duck fatty liver (foie gras), foie gras emulsion and fatty liver fat, as well as regular duck fat, were determined as a function of temperature. Density of foie gras and foie gras fat and emulsion at 20°C was measured as 947, 836, and 928 kg/m³, respectively. Differential scanning calorimetry thermograms for foie gras fat resulted in melting points ranging from –20 to 40°C. Values for the specific heat at 65°C for the fatty liver, its emulsion and fat, and duck fat were 1.79, 2.38, 1.71, and 2.48 J/g°C, respectively. Thermal conductivity of foie gras (organ) and its emulsion at 40°C was determined as 0.330 and 0.428 W/m°C, respectively. Mathematical models based on composition and temperature were developed for all the thermal properties obtained in this work.