Analysis of the Impact of Coulomb Stress Changes of Tehoru Earthquake, Central Maluku Regency, Maluku Province

The Tehoru earthquake occurred due to the release of stress in rocks. There is a release of energy as an earthquake as a result of the rock elasticity limit has been exceeded because the rock is no longer able to withstand the stress. One method to determine the distribution of earthquake stress is the Coulomb stress change method. The study aimed to determine the DCS of the Tehoru earthquake, Seram Island, and the effect of the main earthquake stress release on aftershocks. The research results show that the DCS distribution of the Tehoru June 16, 2021 earthquake is shown with negative lobes and positive lobes. The negative lobe is found in an area that is perpendicular to the fault plane and has been identified as having experienced relaxation, so there may be still aftershocks with stress values ranging from (0.0 – 0.3) bar. The dominant positive lobe occurs next to the southern end of the fault plane, too much located in the area of increasing Coulomb stress with values ranging from (0.2 - 0.6) bar

On the selection of the most plausible non-linear axial stress–strain model for railway ballast under different impulse magnitudes

The effective maintenance and health monitoring of ballasted railway tracks, which involves the determination of differential settlement, track support stress and stiffness, and the strain-hardening property of ballast, is essential. The vertical stress–strain behavior of the ballast layer is primarily responsible for the irrecoverable strains and settlements in tracks, leading to further track degradation. This article reports the development of a series of applicable yet simple uniaxial models and the selection of the most plausible one for capturing the behavior of vertical stresses and strains in ballasts utilizing a set of measured vibration data of the rail–sleeper–ballast system from a Bayesian perspective. From the literature, the dynamic behavior of ballast can be divided into linear and non-linear regions. Under small amplitude vibration, the stress–strain property is linear and elastic, while the behavior becomes non-linear and inelastic once the elasticity limit is exceeded. By integrating the linear phase to some well-known non-linear engineering material laws, a list of new ballast stress–strain model classes was developed. An enhanced Markov chain Monte Carlo–based Bayesian scheme was utilized to explicitly handle the uncertainties in the model updating process, while the Bayesian model class selection method was employed to select the most plausible ballast stress–strain model class under the prevailing system conditions. The proposed methodology was verified using three sets of measured acceleration data from impact hammer tests on an in situ sleeper with simulated ballast damage. The obtained results suggest that the linear-elastic model is sufficient for small amplitude vibrations, while the modified Voce model is the most plausible amongst the investigated model classes for high impact load. The results also demonstrate the importance of the non-linear ballast model in ballast damage identification and the potential applicability of the selected ballast model in field track monitoring.

THE SIMULATION OF MECHANICAL STIMULATION EFFECT ON BONE ELASTICITY LIMIT BASED ON FINITE ELEMENT METHOD (FEM)

Osteoporosis is a disease affecting bones which is characterized by decreased bone density; bones become porous and susceptible to fractures. Osteoporosis occurs because of an imbalance during bone remodeling phase between resorption and formation processes. This study aims to simulate the effects of mechanical stimulations on the femoral bone elasticity limit. It is hoped that these mechanical stimuli can provide information on bone elasticity limits. Initially, we constructed the femur in two layers using triangular elements. Then we entered the bone properties (Young’s modulus and Poisson’s ratio) based on the age of the femur. After that we calculated the value of the stress, strain, and strain rate in the reversal phase. Next, we calculated the bone density using the thermodynamic equation and calculation of the bone elasticity limit using particle swarm optimization (PSO) methods. The value of stress and strain caused by walking is higher than the value of stress and strain when standing still. In this case, the difference in activity results an increase in stress by 33.82% and an increase in strain and strain rate by 34.57%. Based on these simulation results, it can be concluded that mechanical stimulation can increase the limit of bone elasticity to 2.99% in cortical bone and 0.975% in trabecular bone. Bone elasticity limit can be used to determine the level of osteoporosis that occurs. The higher value of the bone elasticity, the smaller the possibility of osteoporosis.

Design Go-Kart Chassis Four Strokes 110 Engine

This study aimed to decide how to design a kart chassis and the strength of the welded joints. In this design, the chassis frame is made of tubular profile steel, which is designed to withstand most of the loads in a vehicle. The chassis was designed using a computer application, namely Auto CAD 2007. Assembly using carbon steel pipes connected using SMAW welding with E6013 RB 2.6 mm welding wire with a current of 75 A, 1G place. The test is carried out with a tensile testing machine. The material is pulled past the most stretch elasticity limit until finally, the specimen reaches the limit (breaks). The tensile test takes about 3-5 minutes with a load of 10-20N. The test results show the average tensile strength of the iron pipe is 0.512 Mpa.

Atomistic Simulation Study of Mechanical Deformation of Al-Mg-Si Alloys

Aluminum alloys have been attracting significant attention. Especially Al-Mg-Si alloys can exhibit an excellent balance between strength and ductility. Deformation mechanisms and microstructural evolution are still challenging issues. Accordingly, to describe how the type of phase influence mechanical behaviour of Al/Mg/Si alloys, in this paper atomic simulations are performed to investigate the uniaxial compressive behaviour of Al-Mg-Si ternary phases. The compression is at the same strain rate (3.1010 s−1); using Modified Embedded Atom Method (MEAM) potential to model the deformation behaviour. From these simulations, we get the total radial distribution function; the stress-strain responses to describe the elastic and plastic behaviors of GP-AlMg4Si6, U2-Al4Mg4Si4 and β-Al3Mg2Si6 phases. For a Detailed description of which phase influence hardness and ductility of these alloys; the mechanical properties are determined and presented. These stress-strain curves obtained show a rapid increase in stress up to a maximum followed by a gradual drop when the specimen fails by ductile fracture. From the results, it was found that GP-AlMg4Si6 & U2-Al4Mg4Si4 phases are brittle under uniaxial compressive loading while β-Al3Mg2Si6 phase is very ductile under the same compressive loading. The engineering stress-strain relationship suggests that β-Al3Mg2Si6 phase have high elasticity limit, ability to resist deformation and have the advantage of being highly malleable. Molecular dynamics software LAMMPS was used to simulate and build the Al-Mg-Si ternary system.

The limit state of concrete and reinforced concrete rods at complex and longitudinal-transverse bending

The work considers rods with a constant cross-section. The deformation law of each layer of the rod is adopted as an approximation by a polynomial of the second order. The method of determining the coefficients of the indicated polynomial and the limit deformations under compression and tension of the material of each layer is described with the presence of three traditional characteristics: modulus of elasticity, limit stresses at compression and tension. On the basis of deformation diagrams of the concrete grades B10, B30, B50 under tension and compression, these coefficients are determined by the method of least squares. The deformation diagrams of these concrete grades are compared on the basis of the approximations obtained by the limit values and the method of least squares, and it is found that these diagrams approximate quite well the real deformation diagrams at deformations close to the limit. The main problem in this work is to determine if the rod is able withstand the applied loads, before intensive cracking processes in concrete. So as a criterion of the conditional limit state this work adopts the maximum permissible deformation value under tension or compression corresponding to the points of transition to a falling branch on the deformation diagram level in one or more layers of the rod. The Kirchhoff-Lyav classical kinematic hypotheses are assumed to be valid for the rod deformation. The cases of statically determinable and statically indeterminable problems of bend of the rod are considered. It is shown that in the case of statically determinable loadings, the general solution of the problem comes to solving a system of three nonlinear algebraic equations which roots can be obtained with the necessary accuracy using the well-developed methods of computational mathematics. The general solution of the problem for statically indeterminable problems is reduced to obtaining a solution to a system of three nonlinear differential equations for three functions - deformation and curvatures. The Bubnov-Galerkin method is used to approximate the solution of this equation on the segment along the length of the rod, and specific examples of its application to the Maple system of symbolic calculations are considered.

SIMULATION OF THE MECHANICAL STIMULATION EFFECT ON THE PEN JUNCTION BETWEEN BONE AND PELVIC BASED ON FINITE ELEMENT METHODS

Bone remodeling process influenced by cells osteoblast and osteoclast. The remodeling of cortical and trabecular influenced by mechanical stimuli. In this study, cortical and trabecular bones of 25 years old humans were observed, and the result was the cortical bone has the average Young’s modulo 17.9 MPa with the Poisson’s ratio of 0.4. Trabecular bone has the average Young’s modulo of 13 MPa and the Poisson’s ratio of 0.5. The metal orthopedic bone screw, which has used in this research simulation, was is a Titanium screw. The screw has Young’s modulo of 110 GPa and the Poisson’s ratio of 0.29. The results of the simulation of femoral bone elasticity limit with standing activity at the age of 25 were found in the left femur of 112.9416 MPa and the right femur of 115.5134 MPa. The limit of elasticity of the femur due to walking was found in the left femur of 115.2166 MPa with an accuracy of 94.11% and the right femur of 117.6692 MPa.