Papers by Keyword: Size Effect

Abstract: Springback is an important factor influencing forming precision in bending process, which becomes more complex for micro metal foil due to the size effect existing. Bending springback is studied through the micro bending experiments designed with different grain sizes and foil thicknesses using T2 purple copper in this paper. The accurate stress-strain relationships are obtained based on the copper foil tensile experiments; the bending process of micro-component is simulated based on both dynamic explicit and static implicit codes. Comparison of simulation results with experimental results shows that: thickness can serve as an important parameter effecting on the springback; the trend of springback amount rising with a thickness diminishing enhances in small size; sheets with same thickness exhibit phenomenon of springback angle reducing with an increasing grain size. Bending springback of micro metal foil indicates obvious size effect on foil thickness and grain size.

Abstract: Laminated veneer lumber is taken as an object of study, and use LVL specimens of different sizes for compression test and tensile test. The goal of the experiment is to investigate the size effect on compressive strength and tensile strength as well as the influence of the secondary glued laminated face, which appears in the secondary molding processes. The results show that both compressive strength and tensile strength have the size effect apparently and the existence of the secondary glued laminated face lower the compressive strength of LVL specimens. Afterwards, the relationship between compressive strength and volume along with tensile strength and area are obtained by the test results.

Abstract: Micro hydroforming has an ability to manufacture complex 3D micro parts at a high production rate and has drawn increasing attentions. Brief understanding of macro hydroforming, for instance, deep drawing, is necessary to understand the principle of micro hydroforming. Then, special phenomena, such as size effects, occurred at micro scale are discussed and the related theories explaining these phenomena are introduced. Based on the similarities and differences between micro and macro hydroforming, experiments and simulation which consider the size effects are reviewed.

Abstract: The consolidation test was performed to samples of fresh soft dredger fill with heights of 2cm, 3cm and 4cm with full-automatic pneumatic consolidometer. The results show that: the soil sample deforms greatly during the consolidation with significant decrease in water content and small consolidation coefficient. The sample height has negligible effect on the deformation rate, compression modulus, compressibility coefficient, etc., while it is closely related to the consolidation coefficient with an inverse relationship.

Abstract: Studies on size effect around deformation performance of RC members are carried out relatively fewer at present. This article evaluated bending deformation capacity and size effect characteristics of RC cantilever beams by means of test method. And decomposed various deformation components with size effect factors considered, including bending, shear and bar-slip deformation and so on. The article focus on discussing bending deformation components at different loading stage and putting forward corresponding distribution functions. Calculation and experimental results show that bending deformation characteristics have significant differences on specimen dimensions, especially in nonlinear loading stage after longitudinal reinforcement yielding. Large size members have a significant concrete crushing process. ductility reserves show a growing trend with specimens size increasing. Bending deformation ability depends on average stiffness along overall beam before longitudinal reinforcement yielding. After plastic hinge forming, its bending performance will be decided by average stiffness within hinge region equivalent length.

Abstract: With the rapid development of reinforced earth technology, different reinforced materials are also gradually applied to Reinforced earth. In this paper, we focus on the need for the study of interface characteristics between different reinforced materials and clay, by making indoor drawing test with two kinds of reinforced materials commonly used in engineering and the same clay. The test results show that: the drawing strength between the two reinforced materials and clay both increase with the normal stress increasing, both of their strength envelopes are straight lines; In the drawing test between the warp knitted geogrid and clay, the cohesive strength is 6.65kPa, the friction angle is 21.03°; while the drawing test between the geonet and clay, the cohesive strength is 2.9kPa, the friction angle is 10.96°; The average tensile strength of warp knitted geogrid is 26.4% of genet's, while the drawing strength of warp knitted geogrid in the test is about 48.1% of genet's, so when chosing reinforced materials in some engineerings, it is an important factor that we must consider the particle size and gradation of the filled reinforced materials, selecting the most appropriate size effect.

Abstract: In special situations the fatigue properties of the construction material can be determined using non-standard specimens, for example smaller than the normative ones (the so-called mini specimens). The research presented was made for the aluminum alloy based on the high-cycle fatigue testing methodology. The verification was made by breaking down the results with own tests which involved the use of standard specimens and stands as well as with the literature reports.

Abstract: With the increasing demand for high efficiency, low cost and the bulk, so the production of micro-forming has a very important significance. Firstly, the introduction of micro-forming is introduced in this paper. Then, its basic theory, including size effects and temperature effects, is presented. At last, a future research direction is highlighted.

Abstract: Size effect of tunnel excavation in fractured rock mass was analyzed with UDEC in this paper. For simplicity, two series of orthogonal equidistant joints were conceived in the calculation area. Change the excavation size and keep the constitutive model and its parameters of the rock mass around the tunnel to be constant during the solution. The result show, with the increasing of excavation size, vertical displacement of tunnel roof become larger, and the excavation stability turn weaker. So excavation size has great effect on the stability of fractured tunnel. In addition, another key factor, the joint set dip angle, whose effect to the tunnel stability was unearthed by comparing the results of horizontal and 45°joints. The larger the dip angle the weaker the stability at the same tunnel size.

Abstract: 5 nm BaTiO₃ powder has been successfully prepared by the one-step solvothermal method. The different grain size BaTiO₃ powders have been achieved after calcining the 5 nm Nanocrystalline BaTiO₃ powders at 700°C, 850°C and 950°C for 3 h. In-situ heating Raman spectroscopy revealed the dispersive phase transition character in the nanocrystalline BaTiO₃ powders. As the BaTiO₃ grain size decreases, wider phase transition temperature and the Raman intensity becomes weak. The BaTiO₃ powders of the 5 nm nanocrystalline exhibited the similar phase transformations from rhombohedral to orthorhombic to tetragonal to cubic transitions as those in the coarse BaTiO₃ ceramics.