Energy Absorption Process Research Articles

Compression behavior of strut-reinforced hierarchical lattice—Experiment and simulation

The reinforcement design of lightweight lattice is a hot spot to seek for higher mechanical performance. In this study, the strut-reinforced concept is proposed from the perspective of space filling. The specimens with 4 × 4 × 4 cells were fabricated through Selective Laser Melting (SLM) technique with the metallic 316L stainless steel. The mechanical response and deformation mechanism were investigated by means of quasi-static compression test and numerical simulation. Superior performance was obtained in strut-reinforced hierarchical lattices compared with conventional one, in terms of total energy absorption, specific energy absorption, mean force and deformation process. The filled effect, ribbed effect and interaction effect of specific parts generated by the hierarchical configuration were proved to enhance the compression behavior. The influence of geometry variations on mechanical response was determined and the function of struts becomes more dominant as the diameter increases. In addition, the reinforcement mechanism was revealed via comparing the different deformation characteristics. Afterwards, the bearing capacity of the reinforced lattice subjected to oblique loading was compared with conventional lattice.

Numerical modelling study of a modified sandbag system for ballistic protection

Modern field fortification systems are very large and cause a logistical burden during setup, thus setting the requirement for their modification. A simulation study was conducted to study the correlation between the compaction of sand and the energy absorbed by it when impacted by a solid steel projectile at 850 m/s. Furthermore, the sandbag was modified by the addition of plates in the system to observe the change in projectile penetration and the energy absorption behaviour of the sand. The factors considered for this study were the plate thickness (15 mm, 25 mm), plate material (aluminium, concrete, plexiglass, polycarbonate, steel) and plate location (226 mm, 236 mm, 256 mm from the point of impact). It was observed that a layer of compressed sand is formed around the projectile, aiding the energy absorption and dissipation process during impact. Upon addition of the plate, it was observed that the modified system (plate and sand) absorbed maximum energy when the plate is placed closest to the point of maximum penetration without the plate. It was also noted that the addition of the plate enhanced energy absorption characteristics of the system compared to conventional sandbags because of increased compaction of sand. From the study, it was observed that the plexiglass and polycarbonate plates had the maximum energy absorption and maximum deformation. The steel plate had the least energy absorption and minimal deformation. Concrete and Aluminium had comparable areal density, energy absorption and lowest deformation, making them the preferred choice of plate material for a modified sandbag. The numerical studies were verified using a gas gun and a modified sandbag with Aluminium plates to show that the addition of a plate improves compaction behaviour of sand.

Mechanical response and energy dissipation characteristics of granite under low velocity cyclic impact

In the process of metal ore blasting mining, the surrounding rock in the middle and far area will still be affected by the stress wave generated by the explosion, resulting in the damage and strength reduction of surrounding rock. The fracture process of rock under cyclic impact load is a process of energy absorption and dissipation. The research on the mechanical properties and energy dissipation law of surrounding rock under low velocity cyclic impact has a good reference for the research on the damage law of rock under weak impact environment. In this paper, the granite samples collected from Sanshandao Gold Mine in Laizhou City, Shandong Province were subjected to cyclic impact tests by using a 50 mm diameter split Hopkinson pressure bar (SHPB) test device. The stress-strain evolution law and energy dissipation law of the specimen in the process of damage and fracture are mainly studied. The results show that the dynamic process of a large number of void defects (such as voids, dislocations, microcracks, etc.) in granite under cyclic impact load is strengthened, and the damaged core is formed and propagated, leading to tensile fracture; With the accumulation of strain energy, the damage situation intensifies, and then affects the stress propagation, so that the ratio of incident energy to reflected energy increases linearly with the accumulation of strain energy, and the ratio of transmitted energy also decreases linearly.

Study of collision characteristics of water-filled double-layer structure

Water-filled double-layer structures are typical hull structures. However, the effect of the carried water has often been neglected in previous collision studies. The carried water couples with the hull structure and participates in the energy absorption process, which reduces the collision damage done to the hull structure. This paper focuses on the effects of compressible carried water on the collision characteristics of a hull structure. Therefore, collision experiments with a simplified double-layer structure (water tank) were performed, and the corresponding collision process was simulated with the finite-element method. The two kinds of pressure (a shock wave and pressure disturbance) generated in the carried water when the water tank collides with a striker were investigated. By comparing the dynamic characteristics of empty and completely filled water tanks, it can be observed that the pressure of the carried water can reduce the displacement of the outer plate and change its deformation shape. Furthermore, the effects of pressure on the collision force and displacement of the inner plate were investigated. Finally, the collision characteristics of a typical water-filled side structure are presented as an example.

Design and Numerical Simulation of a Ball Cutting Type Energy Absorber Device

This paper is verified by numerical simulation and experiment. Based on the principle of energy absorption in metal cutting process, this paper presents a new type of energy absorption structure, which can improve the collision performance of urban rail vehicles. The structure is composed of solid energy absorption tube, hard ball, anti-crawling board and mounting board. Based on the nonlinear dynamic simulation theory and the explicit algorithm of finite element software ABAQUS, the finite element model of the structure of the cutting type energy absorber was established, and the energy absorption process was simulated. Based on the verified simulation model, the influences of the design parameters such as the cutting depth and the number of balls on the energy absorption process are analyzed. It is found that the design parameters affect the cutting force and energy absorption, and the structure has a good energy absorption effect during the collision.

Experimental study of the processes of dynamic energy absorption of sand-lime brick

The data obtained as a result of dynamic tests of sand-lime brick samples were used to estimate its energy intensity. The experiments were carried out according the Kolsky method using a split Hopkinson bar. The graphs of the specific energy absorption of sand-lime brick were obtained at different deformation rates as a result of the numerical integration of dynamic deformation diagrams. In addition, dependences characterizing the growth of energy characteristics with an increase of the strain rate are plotted. Comparison of the studied properties of sand-lime brick with same properties of other brittle media is carried out.

The Mechanical Properties of Fiber Metal Laminates Based on 3D Printed Composites.

The production and mechanical properties of fiber metal laminates (FMLs) based on 3D printed composites have been investigated in this study. FMLs are structures constituting an alternating arrangement of metal and composite materials that are used in the aerospace sector due to their unique mechanical performance. 3D printing technology in FMLs could allow the production of structures with customized configuration and performance. A series of continuous carbon fiber reinforced composites were printed on a Markforged system and placed between layers of aluminum alloy to manufacture a novel breed of FMLs in this study. These laminates were subjected to tensile, low velocity and high velocity impact tests. The results show that the tensile strength of the FMLs falls between the strength of their constituent materials, while the low and high velocity impact performance of the FMLs is superior to those observed for the plain aluminum and the composite material. This mechanism is related to the energy absorption process displayed by the plastic deformation, and interfacial delamination within the laminates. The present work expects to provide an initial research platform for considering 3D printing in the manufacturing process of hybrid laminates.

A novel FRP composite with high-strength, high extensibility in tension: 1-D constitutive relation

A FRP reinforcement has been developed to deliver desired nonlinear stress–strain responses upon various demands for reinforcements in Civil Engineering. The application of this FRP reinforcement will get rid of corrosion and achieve favourable interactions between reinforcement and other structural materials, suggesting a new paradigm especially for reinforced concrete elements. Suitable numerical models in aid of guiding their fabrication upon diverse demands are essential but yet presented. In this paper, a simple but robust one-dimensional (1-D) constitutive model has been developed for predicting the behaviour of the FRP reinforcement under the tension. The proposed model considers a detailed description for the 2D arrangement of the FRP reinforcement that characterizes the texture by non-linear beam-column and bar elements. The model has been validated by experimental measurements and sophisticated FE models. It is shown that the use of proposed model allows the consideration of different loading behaviour and energy absorption processes upon increasingly updated demands for more sophisticated and efficient FRP reinforcement in the future.

Energy absorption parameters of multi-cell thin-walled structure with various thicknesses under lateral loading

Energy absorbers are widely used in many engineering structures, especially mobile ones to prevent or alleviate the impact damages. Thin-walled structures are employed as an important category of energy-absorbing systems. In this study, the effect of thickness variations in different parts of a particular structure is investigated on the energy absorption behavior. The geometry of the considered structure is a four-cell squared-section of aluminum alloy 6061 that is subjected to the lateral loading and the thicknesses of the sides are defined as the input variables. For the systematic investigation of the input variables effect, design of experiments procedure is utilized. The simulations are performed by the LS-Dyna software using the finite element method based on the output data of design of experiments. Moreover, in order to ensure the accuracy and validity of the simulations, an experimental investigation has been conducted for one of the scenarios and the results are confirmed. According to the results of numerical investigations, it was found that all the input variables of the problem are effective with distinct and considerable trend in energy absorption of the structures. These trends are generally nonlinear and relative extremum can be observed in some of them. Finally, by analyzing the energy absorption process of the structures by response surface methodology, an optimal sample is selected and simulated; moreover, the identical sample is also subjected to experimental tests. The results showed approximately 272% enhancement in the specific energy absorption of the optimal sample in design of experiments table compared to the weakest one.

Inhomogeneous generation of hydroxyl radicals in hydrogen peroxide solution induced by ultraviolet irradiation and in a Fenton reaction system

The density of hydroxyl radical (•OH) generation by degeneration of hydrogen peroxide (H2O2) during UVB irradiation and in a Fenton reaction system was estimated. The purpose of this study was to evaluate whether these reaction systems generate spatially uniform or inhomogeneous •OH from H2O2 in the reaction mixture. A series of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) solutions of several concentrations (0.13‒1661 mM) were prepared. For UVB irradiation, 1 μl of 98 mM, 980 mM, or 9.8 M H2O2 solution was added to a 100-μl aliquot of DMPO solution, and the reaction mixture was irradiated with UVB. For the Fenton reaction, 1 μl of 98 mM H2O2 and 1 μl of 100 mM FeSO4 were added to a 100-μl aliquot of DMPO solution. After UVB irradiation or adding FeSO4, the entire volume of the reaction mixture was drawn into PTFE tubing and measured by X-band EPR. The DMPO-OH concentration in the reaction mixture was plotted versus the molecular density of DMPO, and the density of •OH generation was estimated from an inflection point on the plotted profile. The local densities of the UV-induced •OH in the H2O2 water solutions depended on the concentration of H2O2 in the solution, and were likely localized. The energy absorption process of photons was suspected to occur in a step-wise manner in a limited volume. •OH generation in the Fenton reaction system was expected to be uniformly distributed, but inhomogeneous •OH generation was observed at the molecular level.

LABOR IN FOREIGN COMPANIES ASSOCIATED WITH THE PRINCIPLES OF NATIONAL TREATMENT IN GATS / WTO FRAMEWORK

Since The Issuance Of Law No. 1 Of 1967 Concerning Planting Foreign Capital And Is Now Replaced By-Law No. 25 Years 2007 Regarding Investment There Are No More Foreign Companies Nationalized By The Government And There Is A Political Promise Of The President Who Guarantee There Will Be No Nationalization Of Foreign Companies In Indonesian Regional Foreign Investment Forum. Although There Is Protection Nationalization Of Foreign Companies There Are Various Government Policies For The National Interest, One Of Which Is By Requiring Foreign Companies To Use Local Labor Which Can Be Called The Indonesianization Of Labor In The Company Foreign Law Contained In Act Number 13 Of 2003 Concerning Employment Article 43 To 49. Indeed This Is Indonesia's Sovereignty To Protect Its Domestic Interests Especially The Rights Of Its Citizens To Get Jobs, But Within Indonesia's International Trade In Services Must Comply Various Agreed International Regulations Listed In The GATS / WTO, Whether Indonesianization Of Workers In Foreign Companies This Is Following The Principle Of National Treatment In GATS And Whether This Government Action Is Following The Provisions In The GATS / WTO. By Conducting Descriptive Analytical Research With Methods Normative Juridical Approach, The Author Will Examine Various Regulations National Legislation Related To The Use Of Labor In Foreign Companies And Compare Them Whether This Is Following Existing International Agreements, Especially Within The GATS / WTO. The Results Of This Study Indicate That The Indonesianization Of Workers In Foreign Companies Does Not Violate The Principle Of National Treatment GATS Due To Indonesianization Of Labor Also Applies In Companies Domestic. Indonesianization Are Energy Absorption Processes Local Work In A Foreign Company As A Way Of Dealing With It Globalization Of Trade In Services Contained As One Type Services That Have Been Regulated In GATS Are Commercial Presence.Keywords: Indonesianization of Labor, National Treatment, GATS / WTO

Mechanical design and energy absorption performances of novel dual scale hybrid plate-lattice mechanical metamaterials

In this paper, novel dual scale hybrid mechanical metamaterials consisting of simple cubic structure (SC), body-centered cubic structure (BCC), face-centered cubic structure (FCC) unit cells at different scale levels were designed and proposed for impact energy absorption, where one large type A unit cell and eight (2 × 2 × 2) small periodicspatially architected type B unit cells with half size of type A unit cell along X, Y and Z directions were integrated together for harvesting final hybrid metamaterials. Comparisons of specific energy absorption performances between novel hybrid mechanical metamaterials and constituent simple single type of unit cell lattice during compression process were performed through experimental investigation, where the failure and energy absorption process were recorded using the digital camera. Afterwards, finite element analysis (FEA) was performed and compared with experimental results for investigating the mechanical benefits of novel hybrid Plate-lattice mechanical metamaterials, it was found that the novel hybrid plate-lattice mechanical metamaterials can generate enhanced specific strength, specific stiffness and elevated energy absorption performances indicators, demonstrated promising industrial application potentials as energy-absorbing materials and structures for aerospace, vehicles, transport industrial sections.

A solar membrane-based wastewater treatment system for high-quality water production

Abstract This study proposes a novel solar wastewater treatment system comprising efficient solar energy absorption and contaminant separation processes. The proposed system aims to overcome the drawbacks of previous membrane-based systems especially high energy demand and lack of a complex wastewater consideration. Synthetic wastewater was prepared and the solar system was experimentally analysed under climatic conditions of Perth, Western Australia in summer and winter. The findings revealed that the solar thermal efficiency of the system fluctuated mainly around 63% in summer and 52% in winter. The system reached its maximum exergy efficiency in the afternoon with 5.54% and 4.82% for summer and winter, respectively. Moreover, the highest rate of treated water in summer and winter were 4.21 and 2.85 L/m2h, respectively. The results also indicated that the removal percentages of Fe, Mn, Cu, Na, K, and Ca were 96, 89, 96, 100, 100, and 94%, respectively. In addition, almost 100% of organics and nutrients were removed. The highest recorded gained output ratio and overall efficiency were 0.71 and 49.6% in summer, while these parameters were 0.58 and 46.6% in winter. Overall, the proposed solar-driven membrane-based system is a feasible and efficient option in the separation of contaminants from wastewater.

Simulating the Impact of Urban Surface Evapotranspiration on the Urban Heat Island Effect Using the Modified RS-PM Model: A Case Study of Xuzhou, China

As an important energy absorption process in the Earth’s surface energy balance, evapotranspiration (ET) from vegetation and bare soil plays an important role in regulating the environmental temperatures. However, little research has been done to explore the cooling effect of ET on the urban heat island (UHI) due to the lack of appropriate remote-sensing-based estimation models for complex urban surface. Here, we apply the modified remote sensing Penman–Monteith (RS-PM) model (also known as the urban RS-PM model), which has provided a new regional ET estimation method with the better accuracy for the urban complex underlying surface. Focusing on the city of Xuzhou in China, ET and land surface temperature (LST) were inversed by using 10 Landsat 8 images during 2014–2018. The impact of ET on LST was then analyzed and quantified through statistical and spatial analyses. The results indicate that: (1) The alleviating effect of ET on the UHI was stronger during the warmest months of the year (May–October) but not during the colder months (November–March); (2) ET had the most significant alleviating effect on the UHI effect in those regions with the highest ET intensities; and (3) in regions with high ET intensities and their surrounding areas (within a radius of 150 m), variation in ET was a key factor for UHI regulation; a 10 W·m−2 increase in ET equated to 0.56 K decrease in LST. These findings provide a new perspective for the improvement of urban thermal comfort, which can be applied to urban management, planning, and natural design.

A numerical study on energy absorption capability of lateral corrugated composite tube under axial crushing

In this study, a comprehensive numerical investigation is carried out to evaluate the crashworthy behavior and the energy absorbing capacity of lateral corrugated composite tubes under axial loading. In this regard, a new lateral corrugated circle tube with a sinusoidal cross-section is proposed. To investigate the process of energy absorption, material model 54 in non-linear FE software LS-DYNA is applied for modelling axial crushing behavior. In order to validate the numerical simulations, the crushing results of hollow circular tube with uniform diameter are compared with available experimental data and a good agreement is observed. Afterward, crashworthiness analysis of lateral corrugated composite tubes is conducted by controlling the shape of the cross-section through the amplitude and the number of corrugations. The energy-absorbed performances such as specific energy absorption, initial peak crashing force, and mean crashing force of tubes are analyzed and discussed. Numerical analysis reveals that the lateral corrugated composite tubes have significantly obvious effects on the structural crashworthiness compared with ordinary circular tube under axial loading. Also, the results indicate that the geometrical shape of corrugation plays an important role in increasing the efficiency, controllability and failure patterns of corrugated tubes.

The heating of magnetic nanoparticles in a rotating magnetic field

ABSTRACTThe specific absorption rate of magnetic nanoparticles in a rotating magnetic field has been calculated taking into account both thermal fluctuations of the particle magnetic moments and strong magneto-dipole interactions in nanoparticle clusters with various filling factors. For an assembly of interacting superparamagnetic nanoparticles, the maximal values of the specific absorption rate in a rotating magnetic field are found to be 30–40% greater than that in alternating magnetic field. In addition, for the given filling factor and magnetic field amplitude in rotating magnetic field the nanoparticles in a wider range of diameters can effectively contribute to the energy absorption process. Therefore, the use of rotating magnetic field seems preferable in magnetic nanoparticle hyperthermia.

Energy Absorption of Reinforced Concrete Constructions with Nonlinear Dynamic Deformation

A method is proposed for taking into account the specific features of the energy absorption of reinforced concrete constructions under dynamic loads under non-linear deformation conditions based on the application of the finite element method. Based on the consideration of the triaxial problem, the inconstancy of the energy absorption coefficient throughout the entire volume of the deformable body was revealed. It is shown that the hysteresis energy absorption depends on the level of the stress state and is determined by the deformation properties of materials. The solution of the problem is proposed to be obtained using an iterative process based on the method of integral estimates. Considering that the amount of energy absorbed by the structure depends on the level of the stress state, it becomes possible to control the process of energy absorption by changing the stress-strain state possible by varying the design, fixing conditions, changing reinforcement or any other constructive measures.

Ermittlung der Wasser-Energiedosis nach der Sondenmethode gemäß DIN 6800 Teil 1: Vorschlag für eine Erweiterung der Grundgleichung

For any detector to be used for the determination of absorbed dose at the point of measurement in water a basic equation is required to convert the reading of the detector into absorbed dose in water. The German DIN 6800 part 1 provides a general formalism for that. A further differentiated formalism applicable to photon dosimetry is suggested in this work. This modified formalism presents the two following still general and at the same time fundamental properties of any dosimetry detector: a) a clear distinction of correction factors with respect to the physical processes involved during the measurement, and b) the fact that the process of energy absorption in the detector is determined by the spectral distribution of the fluence of the secondary charged particles. It is concluded that based on the modified formalism and knowing this spectral distribution within the detector a general method is available with benefits for ionization chambers as well as for any other dosimetry detector and which is applicable at reference as well as non-reference conditions without any preconditions.

INVESTIGATION OF REGULARITIES OF PLASTIC DEFORMATION OF HOLLOW STEEL PROFILES BY COMPRESSION

The article studies the kinematics of elastic-plastic deformation of hollow steel profiles. The aim of the work was to improve the power characteristics of the processes of plastic deformation of energy-absorbing structural elements of the hollow profile of vehicles and to increase the passive safety and reliability of equipment. Finite element modeling of kinematics of processes with control of parameters of energy absorption of steel pipes of various cross sections was carried out. The results of virtual studies of bending and precipitation at the end of a number of hollow profiles in the form of pipes of different sections have shown ample opportunities to control the process of mechanical energy absorption by selecting the design of pipes, control the results of modeling the absorbed energy and the maximum effort on the indicator diagram of the deformation process.

Monte-Carlo study of the effect of small admixtures of iron atoms on the energy absorbed by water irradiated by near-Fe1s-threshold photons

Energy absorption processes in iron-doped water under photon irradiation are studied by Monte Carlo simulation with accurate accounting for the cascade decays of vacancies in the electron shells of ionized atoms. Small admixtures of cascade-explosive iron atoms to water are shown to noticeably enhance the energy absorbed near the sites of initial photoionization when incident photon energy exceeds that of the Fe1 s ionization threshold.