Damage comparative analysis of needled C/SiC composite under vibration fatigue loading and monotonic tensile loading

Needled C/SiC composite is composed of fiber and matrix, witch fatigue limit is related to the vibration loading frequency. A kind of plate specimen made of needled C/SiC composite was tested on a shaking table, and the vibration fatigue life of each specimen was obtained. In addition, the monotonic tensile test of needled C/SiC composite specimen was also carried out. Furthermore, the fracture morphologies from vibration test and monotonic tensile test were compared by scanning electron microscope. And the mechanism causing these differences was also explained.

Pengaruh Pelarut Metanol terhadap Alumunium sebagai Wadah Obat Salep Mata

Corrosion is a decrease in the quality of a material or metal due to electrolyte reactions in the environment that affect the life of the material. Corrosion rate is the speed of propagation or speed of decline in the quality of a material with time. Corrosion processes occur in acidic environments, sea water, rain water, and soil are the result of chemical reactions that are also caused by electrochemical processes. The purpose of this study is to determine the corrosion resistance of aluminum metal to variations in the solution of Methanol (CH3OH). This study uses aluminum plates that will be immersed 5 days with a solution of Methanol (CH3OH). How to collect data by testing the Scanning Electron Microscopy (SEM) on each aluminum plate specimen that has been treated with corrosion by heating at a temperature of 60 oC. Methanol solution is one of the factors causing corrosion of metals. If in the free environment, air, temperature, and acidic substances are most commonly found as a factor causing corrosion. The increased corrosion rate is due to the higher concentration of the cause of corrosion. In this discussion Methanol as the concentration used, and aluminum as the metal tested.

Variation of Streaming Potentials with Time under Steady Fluid Pressure in Bone

This paper investigates the streaming potentials’ behaviors when fluid flows through the micropores in bone. An experimental setup was developed for measuring the streaming potentials between two surfaces of a bone plate specimen. It was found that the streaming potentials measured increased almost linearly with time under a constant fluid pressure gradient, which does not agree with the prediction from the classical theory of streaming potentials. To explain the reasons associated with the results obtained, a theoretical model was proposed in which the electric charge densities on the inner surfaces of the capillary are unevenly distributed. A formula was developed for solving the model, and the solutions demonstrate that nonuniform accumulations of electric charges carried by the fluid on the inner surfaces of the microcanals in bone can induce streaming potentials which linearly increase with time during the driving air pressure holding period. This phenomenon represents the specific characteristics of bone. The solution implies that the streaming potentials in Haversian canals, lacunas and canaliculi are not affected by electro-viscous resistance in the bone fluid.

Pengaruh Preheat terhadap Sifat Mekanis Sambungan Metal Inert Gas (MIG) pada Baja Karbon Rendah

<p><em>The objective of this research is to find out the effect of preheat on mechanical properties of the metal inert gas welding (MIG) on low carbon steel. The welding method uses a MIG welding on a low carbon steel strip plate specimen, in the V angle of 60°, using ER70S-6 electrode wire and CO<span style="font-size: 8.33333px;">2</span> for protection, the variable of this research is a preheat temperature of 100 ^oC, 200 ^oC, 300 ^oC and non-preheat. The test results showed that the highest Vickers hardness value is owned by the preheat 200 ^oC temperature with Vickers hardness value of 206.674 kg/mm², the tensile test specimens with preheat 200 ^oC temperature variations have the greatest tensile strength is the average of 54.87 Kgf/mm², the value of the highest impact energy on preheat 100 ^oC of </em>98.399 <em>Joules.</em></p>

Microscopic Elastic and Plastic Inhomogeneous Deformations and Height Changes on the Surface of a Polycrystalline Pure-Titanium Plate Specimen under Cyclic Tension

A cyclic tensile test was carried out using a plate specimen of commercial pure titanium on a digital holographic microscope stage. Microscopic deformation of the grains was observed, and their height distribution was measured on the specimen surface. Each grain showed nanoscopic movement up and down, as well as reverse movement corresponding to specimen loading and unloading. We suggest that the different grain-specific changes in height were caused by microscopic inhomogeneities in the material, such as differences in the crystal orientation and geometries of both the surface and subsurface grains. Changes in grain height increased with tensile load, and a strong relationship was found between the height changes that occurred under elastic and plastic conditions. This suggests that microscopic plastic deformation is predictable from microscopic elastic deformation. In order to investigate the plastic deformation of grains in more detail, slip-line angles were measured after the tensile test. We found slip lines with similar angles in neighboring grains, suggesting that the plastic deformation of grains was not independent, but rather was related to that of surrounding grains and influenced by the deformation of subsurface grains.