Advanced Materials Research Vols. 328-330

Abstract: Glass fiber reinforced aluminum alloy laminates, such as ARALL, GLARE are used widely for aeronautics and astronautics industry with excellent mechanical properties such as high specific strength, specific Young’s Modulus, high damage tolerance, high resistance to fatigue crack growth and good impact resistance. In order to obtain better mechanical properties, aluminum alloy plates and glass fibers were replaced by magnesium alloy plates and carbon fibers to get carbon fiber-metal laminates based on magnesium alloy. Single cantilever beams were used to examine the influence of loading rate on the interfacial fracture toughness of carbon fiber-metal laminates based on magnesium alloy. The results show that crack propagation is stable at low loading rates whereas unstable at high rates. And loading rates have slight influence on interfacial fracture toughness at low rates range from 1mm/min to 1000mm/min. The fracture toughness at high rates in impact tests is greater than at low rate.

Abstract: According to application of thermal insulation materials in the practical construction of electrical heat tracing in viscous oil pipeline, impact factors of rigid polyurethane foam widely used as new insulation material are systemically analyzed by Grey Relational Analysis (GRA) in the theory of Grey System to find out priorities among those factors. To further study their performances and to improve the quality of constructions, ten field experiments were carried out in Tanggula Mountain. The foaming conditions and the performances of the rigid polyurethane foam were recorded to be analyzed by GRA. The analysis results, acting as scientific guidance for construction, show that the insulation quality of rigid polyurethane foam is mainly determined by the ratio of components, thus the priority is to control such dominant factor and overall consideration of other factors should be taken to ensure insulation quality in the foaming process. More field experiments prove that the ratio should be controlled between 1.15 and 1.18 to ensure the thermal insulation.

Abstract: Magnetorheological (MR) fluid is a new kind of smart materials, which can be transformed from Newtonian fluid into visco-plastic solid rapidly in the presence of magnetic field. In this paper, the material composition, characteristics and constitutive relation of this smart material were discussed. The operational principles of MR devices in flow, shear and squeeze mode were generalized in detail. The design technique of structural parameters and magnetic circuit of MR devices were investigated. Especially, some important technical points on dimension of fluid gap, magnetic core material and the direction of magnetic flux density were sumarized. All of these can give a valuable referrence for MR devices design. As an example, a MR damper in shear-valve mode was designed, and some experiments were carried on it. From the experimental result, it shown that the MR damper has an excellent damping force characteristics. This also proved the design technique put forward by author was validated.

Abstract: Forming accuracy is one of the important indicators to evaluate the forming quality of a tubular part by tube hydroforming. However, shape asymmetry on cross-section of tubular part produced by hydroforming with radial crushing (THFRC) inevitably appears due to the friction between the die and the part. In this paper, a circular tube is formed into a square cross-section one by THFRC under the various loading paths and the influence of friction on the forming accuracy of cross-section of the bulged parts is analyzed by using numerical simulation. The results show that the larger the tube is expended to, the lower the forming accuracy is under the identical coefficients of friction (COF); the larger the COF value is, the lower the forming accuracy is under a constant maximum hydraulic pressure. In a word, a reasonable loading path and a low COF value can observably improve the forming accuracy of the bulged tube.

Abstract: The influence of phase transformation cycle times on the plasticity and microstructure of FeMnSiCrNi alloy was researched in this paper. The results show that phase transformation cycling can significantly improve the plasticity of the alloy. Plasticity is improved with the increase of cycles. The elongation gets to 87.6% after 5 cycles, it increases 150% compared with non-treated. The more cycle times, the grain is smaller. During the inverse transformation the second phase directional precipitation significantly harden austenite and improve the reversibility of stress-induced martensite. Due to interaction of the second phase strengthening and grain refinement, the plasticity and strength of alloy are both increased significantly. This method provides a new way for the realization of transformation superplasticity.

Abstract: With the Superplastic forming technology, the problem that the forming of the complex titanium alloy parts is difficult has been solved. The high temperature forming characteristics of the titanium alloy material and the establishment of the constitutive model of material that will be used as the material model of the simulation of the material forming (the minimum thickness is larger than 0.8 mm) about the negative Angle parts are based on high-temperature tensile test. The influence of the thickness of the parts is analyzed from three different SPF schemes, which are simulated by the MSC.MARC software. The results demonstrate the parts taking advantage of two-stage SPF, which is consisted of concave die SPF method and convex die SPF method can meet the requirement of minimum thickness and improve the thickness distribution on the die draft sides. Furthermore, the thickness distribution of the parts is more uniform with the convex die SPF method.

Abstract: Wrinkling, wall thickness overthinning and cross-section distorting are main defects that seriously affect the forming quality of the tube in bending process. In this paper, numerical simulation based on PAM-STAMP 2G is conducted for the tube rotary-draw bending filled with steel balls as pressure transferring medium to analyze the deformation behaviors under various internal pressures. The results show that, tube bending filled with steel balls as pressure transferring medium can effectively restrain the defects of wrinkling and cross-section distorting. In addition, wrinkling and cross-section distorting of the bent tube decrease, the wall thickness thickening at the intrados of the bent tube decreases while the wall thickness thinning at the extrados increases with the internal pressure.

Abstract: Fish wastes such as bones and skins, has been under-utilized. Gelatin was extracted from frozen Arrowtooth flounder (Atheresthes stomias) skin (AFS), and the edible gelatin film was successfully prepared. The results showed that the proximate composition of moisture, protein, lipid and ash of the extracted gelatin was 6.0 %, 92.8 %, 0.31 % and 0.39 %, respectively. The pH, bloom strength and viscosity of gelatin was 6.0, 234.8 g and 4.3 mPa.s, respectively. The tensile strength (TS), elongation at break (EAB), solubility and the prepared edible film were 10.3 MPa, 51.4 %, 98.3 %, and the film was transparent.

Abstract: In this paper, polypropylene (PP) melt blown non-woven fabric is treated by atmospheric He, He/O₂ or He/CO₂ glow discharge plasma. The variation of the surface hidrophilicity of PP sample is experimentally investigated by the surface water contact angle. The results show that the surface water contact angle firstly has a sharp decline and then up to saturation. It is worth noting that the time the water contact angle is up to saturation greatly shortens when a spot of O₂ or CO₂ are added into the atmospheric He. In addition, when the PP samples are treated by the atmospheric glow discharge plasma, it is necessary of selecting a right applied voltage.

Abstract: Micro-plastic deformation was produced on the surface of the laser cladding layer by micro-forging, thus cracks were healed in cladding layer; in order to reduce the thermal stress, preheating the substrate was needed to reduce the temperature gap between cladding layer and substrate. In this paper, temperature field by micro-forging on laser cladding Ni60 layer was simulated on software named DEFORM-2D. Compared the width of cracks, the results showed that reasonable and effective preheating temperature could ensure to reduce or eliminate cracks on laser cladding layer.