Natural and experimental high-pressure, shock-produced terrestrial and extraterrestrial materials

Hypervelocity impacts are among the fundamental phenomena occurring during the evolution of the solar system and are characterized by instantaneous ultrahigh pressure and temperature. Varied physicochemical changes have occurred in the building blocks of celestial bodies under such extreme conditions. The constituent material has transformed into a denser form, a high-pressure polymorph. The high-pressure polymorph is also thought to be the constituent of the deep Earth’s interior. Hence, experiments using a high-pressure and temperature generating apparatus have been conducted to clarify its crystal structure, pressure–temperature stability range, and transformation mechanisms. A natural high-pressure polymorph (mineral) is found from terrestrial and extraterrestrial rocks that experienced a hypervelocity impact. Mineralogists and planetary scientists have investigated high-pressure minerals in meteorites and rocks near terrestrial craters over a half-century. Here, we report brief reviews about the experiments producing high-pressure polymorphs and then summarize the research histories of high-pressure minerals occurring in shocked meteorites and rocks near terrestrial craters. Finally, some implications of high-pressure minerals found in impact-induced shocked rocks are also mentioned. Graphic abstract

FATIGUE FAILURE OF FIBROUS COMPOSITE BASED ON MULTISCALE APPROACH

A framework was presented for a fatigue failure model of fibrous composites using a multiscale approach, which uses the fatigue data of the fiber and matrix materials, respectively. Using this model, fatigue failure of fibrous composite materials and structures can be predicted from the constituent material behaviors. To that end, fiber bundles were tested under cyclic loading to determine their residual strength and stiffness. A successful completion of the model is expected to replace many fatigue tests as the configuration of the fibrous composite is varied.

HIGH DAMPING VALUES OF SANDWICH STRUCTURES WITH POLYMER COMPOSITE FACE SHEETS AND FOAM CORES

Structures with high damping and reasonable stiffness values are demanded by designers of aerospace and automotive sectors as these features of the structures are remedies to the vibratory conditions that lead to malfunction of many electronics and mechanical components of aerial and land vehicles. In this study, sandwich structure beams with face sheets of woven carbon fiber-reinforced polymer plies and a foam core have been manufactured to provide high damping performance. For this purpose, first, the beams from the carbon fiber plies with different fiber orientations were subjected to the vibrating beam test with free-free boundary conditions, and their damping and flexural modulus values were obtained. It was found that the plies with 450 angle gave the highest damping value with a reasonable modulus. The same test procedure was also applied to the bare foam beams to obtain their dynamic values. Eventually, the plies with the 450 angle were selected as face sheets for the sandwich beams that yielded reasonably high damping and equivalent flexural modulus values. The data obtained from each constituent material, the laminate face sheets and the core, were used as input data for modal simulations of the sandwich beams using a Finite Element Method.

Plastic Crushing Failure of Bio-Inspired Cellular Hierarchical Topological Sandwich Core

Bio-inspired self-similar hierarchical honeycombs are multifunctional cellular topologies used for resisting various loadings. However, the crushing behavior under large plastic deformation is still unknown. This paper investigates the in-plane compressive response of selective laser melting (SLM) fabricated hierarchical honeycombs. The effects of hierarchical order, relative density as well as constituent material are evaluated. The results show that at small deformation, the AlSi10Mg alloy hierarchical honeycombs show great advantages over the elastic modulus and compressive strength than 316L steel hierarchical honeycombs. As the relative density and hierarchical order increase, the failure mechanism of AlSi10Mg alloy honeycombs gradually changes from a bending-dominated mode to a fracture-dominated mode; whereas all the 316L steel honeycombs fail due to the distortion of original unit cells. At large deformation, the AlSi10Mg alloy honeycombs behave with brittle responses, while the 316L steel honeycombs exhibit ductile responses, showing a negative Poisson’s ratio behavior and gradient deformation of hierarchical unit cells. The addition of unit cell refinements improves the elastic modulus of AlSi10Mg alloy honeycombs and advances the densification of 316L steel honeycombs. In addition, the effect of constituent material on the compressive response of hierarchical honeycombs has been discussed. This study facilitates the development and future potential application of multifunctional ultra-light sandwich structures.

Response Suppression of FGM Plate Using Piezoelectric Layers Under Parametric Uncertainty Conditions with Markovian Jump Approach

It should be noted that in addition to the geometry, constituent material also affects the strength and rigidity of the cylindrical shell, some factors that determine the transient response are its geometry and the constituent material. The capability of piezoelectric materials to adept their properties in reaction to environmental factors including electricity and loading is one of the major reasons for using in this work. Therefore, in this study, the transient response of a symmetric annular sandwich plate incorporating functionally graded core and piezoelectric layers under external harmonic force and electrical voltage is investigated. The properties of the core material vary along its thickness according to a power law model. The displacement field is represented by the third-order shear deformation theory. With the aid of Hamilton’s principle, the structural equations are obtained in terms of displacement components, then solved using the differential quadrature method. In addition, the time response is evaluated with respect to effective parameters including the internal radius, power law index, core thickness, and external voltage. According to the simulation results, the oscillation amplitude decreases as the internal radius of the plate increases over the desired time interval. Also, a higher index parameter is associated with a wider time response range. Moreover, the stability analysis of a piezoelectric system with [Formula: see text] performance is considered based on the theory of Markovian jump systems. To this end, a Markovian jump state-space model of the piezoelectric system obtained using system identification under the effect of external disturbance is presented. The [Formula: see text] stability index is selected based on a candidate Lyapunov function that leads to a set of linear matrix inequalities for each region. The uncontrolled and controlled transient responses of the coupled system under external disturbance are calculated and compared, indicating the satisfactory controller performance in the presence of external disturbance and jump in the sensor and system dynamics.

Kajian Hidrostratigrafi Bentanglahan Kepesisiran Tipologi Marine Deposition Coast Kecamatan Ngambur Provinsi Lampung

This research was conducted on coastal area located in Ngambur Subdistrict, Pesisir Barat Regency, Lampung Province. Geomorphologically, typology of this coastal area formed of marine deposition coast. Which is consist of sandy beach (M1), beach ridge (M2), and fluviomarine (Fm). The purpose of this reasearch is to reconstruct and analyze charactreistic of hydrostratigraphy which is includes of soil stratigraphy system and properties, and physical properties of groundwater in the research area. Vertical distribution of soil resistivity obtained by measuring 24 of measuring points with depth of penetration’s up to 150 meters. Determination of measurement points are selected using purposive sampling method. Furthermore, the resistivity value of the measurement results is calculated using IP2Win software. Results of the calculation matched with soil resistivity tables. Results of the research show that vertically the type of aquifers identified are aquifer, aquitard, and aquifug. The constituent material is dominated by alluvium containing fresh groundwater which acts as an aquifer and sandstone materials which acts as aquitard. The electrical conductivity value (DHL) measured <1,200mmhos / cm which indicates that the groundwater in ths area is classified as fresh groundwater.

A Flexible Two-Sensor System for Temperature and Bending Angle Monitoring

A wearable electronic system constructed with multiple sensors with different functions to obtain multidimensional information is essential for making accurate assessments of a person’s condition, which is especially beneficial for applications in the areas of health monitoring, clinical diagnosis, and therapy. In this work, using polyimide films as substrates and Pt as the constituent material of serpentine structures, flexible temperature and angle sensors were designed that can be attached to the surface of an object or the human body for monitoring purposes. In these sensors, changes in temperature and bending angle are converted into variations in resistance through thermal resistance and strain effects with a sensitivity of 0.00204/°C for temperatures in the range of 25 to 100 °C and a sensitivity of 0.00015/° for bending angles in the range of 0° to 150°. With an appropriate layout design, two sensors were integrated to measure temperature and bending angles simultaneously in order to obtain decoupled, compensated, and more accurate information of temperature and angle. Finally, the system was tested by being attached to the surface of a knee joint, demonstrating its application potential in disease diagnosis, such as in arthritis assessment.

Simulasi Pembebanan Komponen Bender pada Desain Mesin Begel Fabricator Menggunakan Software Autodesk Inventor 2020

Stress analysis of the bender components in the design of the begel fabricator machine was carried out using FEA (Finite Element Analysis) with three variations of the constituent material parameters, namely 6061 aluminum, mild steel, and cast iron with a modulus of elasticity of 68.9 GPa, 220 GPa, 120.5 GPa, respectively. The test is carried out by a loading parameter 2520 MPa and fixed constraint. The maximum von misses stress and displacement obtained for each material parameter components using aluminum, mild steel, and cast iron are 17.78 MPa; 0.00765, 17.49 MPa; 0.00229, 17.62 MPa; 0.00427 respectively.