Applied Mechanics and Materials Vols. 754-755

Abstract: Province of North Sumatera has been well known as a territory having multi kind of industrial minerals which have not been used and maintained properly and optimally. One of which is a natural Pahae zeolite derived from Tarutung, Tapanuli Utara-Indonesia. The objective of this research is to exploit Pahae zeolite to absorb water molecules flowing into the combustion chamber of a hydrogen fueled motorcycle. The generation of water molecules was as a result of water splitting process in water to hydrogen converter of the motorcycle. The grain size of Pahae zeolite was lessened up to 60 and 200 meshes which were then chemically activated by soaking with 30% KOH solution and calcination at a temperature of 300°C for 2 hours. The test results conducted on the intake pipe of combustion chamber showed that the particle size of 200 meshes had more absorption than that of 60 meshes. It was also found that type of Pahae zeolite had better absorption compared with Cikalong zeolite.

Abstract: s. On construction sites many challenges and premature failures are being encountered in welded joints of creep strength-enhanced ferritic (CSEF) steels. The primary reason of these premature failures is found to be the dissimilar material joints, having strength mismatch, or improper heat treatment that is mandatorily carried out to achieve the required weld hardness. This study aims at determining the impact of post welding heat treatment (PWHT) on dissimilar alloy steels joints, between ASTM A335 Gr. P-22 and ASTM A335 Gr. P-91 steels, welded by gas tungsten arc welding (GTAW) using ER 90S-B9 filler wire. The PWHT, at 745°C for 1hr., was applied to attain the required hardness. The effect of PWHT was investigated on the weld metal and the heat affected zones (HAZ) by hardness testing. Due to the martensitic microstructure, the hardness values of HAZ of P91 steel are over 350 HV. However, the hardness value of the P22 HAZ less than 350 HV. P91 HAZ has a higher hardness value than P22 HAZ because of its higher hardenability and due to phase transformation from martensite to ferrite. The interaction between the too high hardness microstructure with hydrogen can result in the hydrogen induced cracking (HIC) initiation in the HAZ. Therefore, the PWHT is needed to reduce this high hardness HAZ.

Abstract: Investigation of impact damage on advanced composite materials of Carbon Fiber Reinforced Epoxy (CFRE) composites and Glass Fiber Reinforced Epoxy (GFRE) composites under high strain rate impact load have been conducted in the present study. Four types of GFRE plates were studied after being impacted with various thicknesses and fixed impact parameters. Results of the present experiments were characterized by the comparison of damage zone among CFRE/GFRE, GFRE with honeycomb core and GFRE without honeycomb core. The result suggests that CFRE is the better structure than GFRE under low velocity impact loads. Higher energy needed to damage the surface of GFRE with core compared to GFRE without core plates.

Abstract: The simulation of Cherenkov light Lateral distribution function (LDF) in Extensive Air Showers (EAS) initiated primary particles such as primary calcium, argon, proton iron nuclei, neutron and nitrogen have been performed using CORSIKA program for conditions and configurations of Tunka133 EAS Cherenkov array. The simulation was fulfilled at the high energy range 10¹⁴-10¹⁶ eV for four different zenith angles 0^o, 10^o, 15^o and 30^o. The results of the simulated Cherenkov light LDF are compared with the measurements of Tunka133 EAS array for the same particles and energy range mentioned above. This comparison may give the good ability to reconstruct the energy spectrum and mass composition of the primary cosmic ray particles in EAS. The main feature of the given approach consists of the possibility to make a library of Cherenkov light LDF samples which could be utilized for analysis of real events which can be detected with different EAS arrays and reconstruction of the primary cosmic rays energy spectrum and mass composition of EAS particles.

Abstract: Titanium alloys are extremely difficult to machining and economically it’s very expensive, so that to minimize the machining cost using the novel bondless diamond grinding wheel, analyze the performance of nanometric finishing in grinding operation. While machining the Ti alloys, the cutting zone temperature is too high, so that to reduce the temperature of cutting zone and favorable change in the chip-grinding using liquid nitrogen (LN₂) coolant for good surface finish.

Abstract: In today’s aviation world, the design of aircraft wing becomes a challenging one for aeronautical engineers, in order to meet the aero elastic phenomenon such as flutter, wing divergence in both aerodynamics and structural aspects. There are so many FEM packages available for both flow and structural analysis such as ANSYS, NASTRAN, ALGOR, NISA, ADINA, COSMOS, etc. The paper presents the application of computational aero-elasticity (CA) methods to analyze the wing in both aerodynamic and structural aspects, using ANSYS-FLOTRAN; 2-D typical aerofoil sections were analyzed and validated with experimental results. Also the vibration behavior of wing section is analyzed under MODAL, HARMONIC, TRANSIENT and SPECTRUM analysis under the aerodynamic lift force and moments. The support reaction forces and moments at the fuselage-wing intersection are developed in this research.

Abstract: Overlay as the conventional method to maintain the surface quality of pavement need a large number of fresh natural aggregate and bitumen due to the relatively thick layer and consequently the road geometric must be corrected, so that regarded as not environmentally friendly. The alternative solution is Ultra-Thin Surfacing Hot Mix Asphalt (UTSHMA) which has a thickness of 12-15mm. UTSHMA gradation is designed based on the highest Marshall Quotient value tested by performing Marshall Test of five variations gradation from Standard Specification Construction of Transport Systems. The Optimum Bitumen Content (OBC) obtained by Marshall Test. The bitumen used for this is 60/70 penetration. The several structural tests were performed on the best gradation at OBC consist of Marshall tests, Indirect Tensile Strength (ITS), Unconfined compressive strength (UCS) tests and water permeability test. The UTSHMA mixture with coarse gradation has the greatest Marshall Quotient at 6.35% OBC accompanied by the higher ITS and UCS properties compare to conventional asphalt concrete. The coefficient permeability of UTSHMA is lower than conventional AC, indicated that UTSHMA is more resistant to water penetration. The research concluded that UTSHMA has compromised the standard specification and has sufficient structural properties compare to conventional AC and can be regarded as structural layer of pavement for overlay and road preservation design.

Abstract: European Union faces challenge in the waste management practices. Despite the economic downturn and the decrease in consumption at European Union level the waste generation stays stable, and the recycling disposal stagnates. Since the level of the recycling and recovery is set at 70% for the year 2020 for the construction and demolition waste for achieving the proposed level practical possibilities for recycling of large quantities are necessary. The paper presents cementitious composites using recycled waste which might represent practical solution for increasing the rate of recycling of construction and demolition waste and of textile industry waste. Mechanical characteristics of two different composites using recycled wastes are presented. The first cementitious composition incorporates recycled aggregates substituting new, non-renewable natural aggregates, while the second composition – beside the recycled aggregates – contains also textile industrial waste. The mechanical characteristics of the obtained compositions are comparable with the ones of the road concrete, in the same time fulfilling also the norm requirements for composites used for road concrete. The proposed cementitious composites represent significant potential for recycling, and as consequence, potential for achieving the targeted rate of the recycling.

Abstract: The effects of 1% tin (Sn) addition on the densification of pre-alloyed and pre-mixed W-brass composites were carried out. The green compacts were produced with the pressure of 350MPa and sintered at the temperature of 800°C, 920°C and 1000°C. The Sn addition is aimed at inhibiting the dezincification (selective removal of zinc from an alloy) of the brass component by the elimination of pores and enhances densification. The hardness of the composites increased with increase in temperature, the densification was low at both temperatures while the electrical conductivity remains constant as a result of constant composition in both pre-alloyed and pre-mixed composites. The microstructures revealed pores, which might be as a result of zinc evaporation.

Abstract: Failure behavior of aircraft sandwich panels under bending load has been investigated in this study. In this study focused in effect of support span length under bending load. Three-points bending test was performed to the specimens with various span length 125 mm, 80 mm, 70 mm, and 55 mm. Standard test method and dimensions were adhering to the ASTM C393. Deflection and energy absorption of the sandwich panels have been characterized by the variation span lengths.It was found that the deflection and the energy absorption of the sandwich panels were strongly influenced by the length of support span. In the bending test of sandwich panels at 125 mm support span length, the panel possess the lowest deflection at a critical load which is around 3.26 mm compared to the other support span length. The differences of the collapse load for 55 mm support span length is highly significant. The value of experimental was found at 1.54 kN whereas the theoretical value is 2.65 kN The ability to absorb energy of sandwich panels was affected by the collapse mechanism. It was found that the decrease of support span length increases the absorbed energy in the aircraft sandwich panel.