Advanced Materials Research Vol. 1119

Abstract: As the trend for lighter more efficient structures continues, the requirement for alternative materials follows. One material that has gained attention more recently is porous metallic foam. One drawback to these materials is that there is limited pedigree and understanding of their performance. As with all materials, the use of metallic foam for structures requires knowledge of its mechanical properties; including at high-strain rates. The focus of this paper is to determine the compressive mechanical properties and the influencing parameters for AISI 4340 steel closed-cell foam under high-strain rates (776s^-1 to 3007s^-1). ANSYS commercial finite element code is used to simulate a closed-cell sample under a split Hopkinson pressure bar test. In this paper the pores are considered to be spherical in shape for simplification while various parameters such as the pore size, the number of pores, the distribution of pores, and the strain rate are varied. Each of these parameters gives this material a unique response which is presented in this paper.

Abstract: This article discusses the use of artificial neural networks for solving industrial non-trivial problem, which is undoubtedly modulus of rupture optimization in case of sintered ceramics based on amorphous SiO₂. Melting crucibles made from high purity silica are commonly used for production of high purity silicon ingots that are used in photovoltaic industry. Optimal modulus of rupture is very important variable that is related to the reliability and crucible usage value.

Abstract: It’s very important to select appropriate dimensions for manufacture of honeycomb sandwich. In this paper, the experimental and theoretical methods were compared. The results are proved that the theoretical formula can be applied to engineering design. The impact factor of staties mechanical properties of honeycomb panels also was studied. And a theoretical basis for the design of honeycomb sandwich panels is provided.

Abstract: This article is aimed at determining the mechanical properties of high-strength steel obtained by digital image correlation for specimens with a hole in different rolling direction. This geometry generates a heterogeneous strain field which was measured during the test using a digital image correlation system. The advantage of using a heterogeneous strain field in the identification procedure is that a complex state of stress-strain can be analyzed at the same time and much more information can be obtained in a single test. On the other hand, the stress field cannot be directly computed from the test and a suitable identification procedure must be developed. Here, the virtual fields method (VFM) adapted for large strains and plasticity was used to identify the hardening behaviour and the anisotropy of the material. The values obtained with the VFM were compared with the results from a standard identification made using uniaxial tensile tests.

Abstract: Quality of recycled plastic is usually below than its virgin material. Status of quality compared to its virgin material quality helps producers and consumers to ensure viability of the material both as a manufacturing product as well as a raw material. A set of material testing result table accompanied with radar chart of its ratios proposed as a tool in representing quality indicator of a recycled plastic. An easy identification of lower and lowest quality and also better quality in certain material characteristics help producers and consumers to make a fast evaluation and further decision related to recycled plastic quality improvement and its proper utilization as raw material.

Abstract: Metal foil strain gauges are most widely used for the stress analysis in engineering structures. Typical strain gauge system includes strain sensitive grid, carrier material, and adhesive layer. Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. In the present work, a Finite Element Model is developed in order to study the effect of both adhesive layer and carrier thickness on strain measurements while using strain gauges. To understand the behavior of the adhesive material, mechanical characterization is done on bulk adhesive specimen. Finite Element Analysis (FEA) is carried out with different materials namely epoxy and polyurethane. Initially a single element foil loop is considered for the analysis and further this is extended to metal foil strain gauge with nine end-loops. Finally, the strain variation through thickness of adhesive layer, carrier and strain sensitive grid is obtained from FEA. The results thus obtained are compared with analytical results from Basic Strength of Materials approach.

Abstract: A simple fluorescent iodide ion sensor was fabricated. Ag⁺ was found to specifically induce the aggregation of perylene–3, 4, 9, 10–tetracarboxylate tetrapotassium salt (PTK) in water, simultaneously, fluorescence of PTK was quenched. The resultant PTK–Ag⁺ aggregates showed a "turn–on" fluorescence response for halide ion, especially I^-, and excellent selectivity toward possible interfering anions, contain sulfide.

Abstract: The behavior of parts subjected to simultaneous thermal and mechanical fatigue loads is an area of research that carries great significance in the power generation, petrochemical, and aerospace industries. Machinery with expensive components undergo varying applications of force while exposed to variable temperature working fluids. An example case is found in steam turbines, which subject stainless steel blades to cyclic loads from rotation as well as the passing of heated gases. Accurate service life prediction is especially challenging due to the thermo-mechanical loading being present on the complex geometric profile of the blades. This research puts forth a method for determining crack initiation lifetimes in variably-notched type 304 austenitic stainless steel specimens subjected to differing fatigue and thermo-mechanical fatigue conditions. A base analytical model and genetic algorithm were used to develop phenomenology-informed predictions that fall within a factor of two of the actual crack initiation times.

Abstract: Sodium chloride (NaCl) is often used for warm mist elimination because of its easy deliquescence performance. In this paper, how dosages of NaCl with two sizes affect warm fog was investigated. The changes of light transmittance (T) and fog drops inside the fog chamber were monitored. Results indicate that NaCl particles smaller than 40μm work better than that of 40-100μm, shortening time of the light transmittance recovering to 60%(t_60%) by 83.3% with 25g. Reasons for this are they can decrease the percentages of small droplets, increase that of large droplets and the average sizes of fog drops, which are results from the condensation growth and coalescence growth.

Abstract: Magnetic Barkhausen noise measurements on a welded marine steel plate were performed in a line that passes through the weld bead and extends to the base metal from both sides of the weld. The heat affected zone was characterized by a pattern in the peak height as a function of distance from the weld bead. Barkhausen noise profile analysis by extracting relevant parameters like peak position, profile area and profile half width was also performed. The result showed a clear variation in MBN profile parameters in a way similar to that of the profile peak height. It could be concluded that MBN profile parameters superimposed as a function of measurement distance from the weld bead may provide an accurate determination of the affected material near the weld bead. The variation in MBN profile parameters was enhanced by microstructural and mechanical changes along the measurement line. This experiment demonstrates that the Barkhausen noise profile parameters could be used to track various manufacturing and maintenance processes of steel instead of using a single parameter like the root mean square (rms) to eliminate the variability of results and narrow the tolerance of acceptance criterion.