Comparative analysis of thermodynamic and mechanical responses between underground hydrogen storage and compressed air energy storage in lined rock caverns

Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.

Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

Influence of the boundary effect on the mechanical response test of pavement cushion under the wetting effect of silt

Through a self-developed model test system,the mechanical properties of silt and the deformation characteristics of airport runways were investigated during the period of subgrade wetting.Based on the test results,the reliability of the numerical simulation results was verified.Numerical models with different sizes were established.Under the same cushion parameter and loading width ranges,the effects of the cushion parameters and loading conditions on the mechanical responses of the cushion before and after subgrade wetting were analyzed.The results show that the internal friction angles of silt with different wetting degrees are approximately 34°.The cohesion is from 8 to 44 kPa,and the elastic modulus is from 15 to 34 MPa.Before and after subgrade wetting,the variation rates of the cushion horizontal tensile stresses with the same cushion parameters and loading width ranges are different under the influence of boundary effects.After subgrade wetting,the difference in the variation rates of the cushion horizontal tensile stresses under the same cushion parameter range decreases compared with that before subgrade wetting;however,this difference increases under the same loading width range.Before and after subgrade wetting,the influence of the boundary effect on the mechanical response evaluation of the cushion is not beneficial for optimizing the pavement design parameters.When the cushion thickness is more than 0.25 m,the influence of the boundary effect can be disregarded.

Mechanical response of bridge piles in high-steep slopes and sensitivity study

The bridge piles located in high-steep slopes not only endure the loads from superstructure, but also the residual sliding force as well as the resistance from the slope. By introducing the Winkler foundation theory, the mechanical model of piles-soils-slopes system was established, and the equilibrium differential equations of pile were derived. Moreover, an analytic solution for identifying the model parameters was provided by means of power series method. A project with field measurement was compared with the proposed method. It is indicated that the lateral loads have great influences on the pile, the steep slope effect is indispensable, and reasonable diameter of the pile could enhance the bending ability. The internal force and displacements of pile are largely based upon the horizontal loads applied on pile, especially in upper part.

Mechanical response of transmission lines based on sliding cable element

In order to study the sliding characteristics when the cable is connected with the other rods in the transmission line structures,a linear sliding cable element based on updated Lagrangian formulation and a sliding catenary element considering the out-of-plane stiffness coefficient are put forward.A two-span and a three-span cable structures are taken as examples to verify the sliding cable elements.By comparing the tensions of the two proposed cable elements with the existing research results,the error is less than 1%,which proves the correctness of the proposed elements.The sliding characteristics should be considered in the practical engineering because of the significant difference between the tensions of sliding cable elements and those of cable element without considering sliding.The out-of-plane stiffness coefficient and friction characteristics do not obviously affect the cable tensions.

Unveiling the mechanical response and accommodation mechanism of pre-rolled AZ31 magnesium alloy under high-speed impact loading

Split Hopkinson pressure bar(SHPB)tests were conducted on pre-rolled AZ31 magnesium alloy at 150–350℃ with strain rates of 2150s-1,3430s^(-1) and 4160s-1.The mechanical response,microstructural evolution and accommodation mechanism of the pre-rolled AZ31 magnesium alloy under high-speed impact loading were investigated.The twin and shear band are prevailing at low temperature,and the coexistence of twins and recrystallized grains is the dominant microstructure at medium temperature,while at high temperature,dynamic recrystallization(DRX)is almost complete.The increment of temperature reduces the critical condition difference between twinning and DRX,and the recrystallized temperature decreases with increasing strain rate.The mechanical response is related to the competition among the shear band strengthen,the twin strengthen and the fine grain strengthen and determined by the prevailing grain structure.The fine grain strengthen could compensate soften caused by the temperature increase and the reduction of twin and shear band.During high-speed deformation,different twin variants,introduced by pre-rolling,induce different deformation mechanism to accommodate plastic deformation and are in favor for non-basal slip.At low temperature,the high-speed deformation is achieved by twinning,dislocation slip and the following deformation shear band at different deformation stages.At high temperature,the high-speed deformation is realized by twinning and dislocation slip of early deformation stage,transition shear band of medium deformation stage and DRX of final deformation stage.

Quench characteristics and mechanical responses during quench propagation in rare earth barium copper oxide pancake coils

Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.

Transcriptional activation of glucose transporter 1 in orthodontic tooth movement-associated mechanical response

The interplay between mechanoresponses and a broad range of fundamental biological processes, such as cell cycle progression,growth and differentiation, has been extensively investigated. However, metabolic regulation in mechanobiology remains largely unexplored. Here, we identified glucose transporter 1(GLUT1)—the primary glucose transporter in various cells—as a novel mechanosensitive gene in orthodontic tooth movement(OTM). Using an in vivo rat OTM model, we demonstrated the specific induction of Glut1 proteins on the compressive side of a physically strained periodontal ligament. This transcriptional activation could be recapitulated in in vitro cultured human periodontal ligament cells(PDLCs), showing a time-and dose-dependent mechanoresponse. Importantly, application of GLUT1 specific inhibitor WZB117 greatly suppressed the efficiency of orthodontic tooth movement in a mouse OTM model, and this reduction was associated with a decline in osteoclastic activities. A mechanistic study suggested that GLUT1 inhibition affected the receptor activator for nuclear factor-κ B Ligand(RANKL)/osteoprotegerin(OPG)system by impairing compressive force-mediated RANKL upregulation. Consistently, pretreatment of PDLCs with WZB117 severely impeded the osteoclastic differentiation of co-cultured RAW264.7 cells. Further biochemical analysis indicated mutual regulation between GLUT1 and the MEK/ERK cascade to relay potential communication between glucose uptake and mechanical stress response. Together, these cross-species experiments revealed the transcriptional activation of GLUT1 as a novel and conserved linkage between metabolism and bone remodelling.

Finite element simulation for mechanical response of surface mounted solder joints under different temperature cycling

Nonlinear finite element simulation for mechanical response of surface mounted solder joint under different temperature cycling was carried out. Seven sets of parameters were used in order to evaluate the influence of temperature cycling profile parameters. The results show that temperature cycling history has significant effect on the stress response of the solder joint. Based on the concept of relative damage stress proposed by the authors, it is found that enough high temperature holding time is necessary for designing the temperature cycling profile in accelerated thermal fatigue test.

Mechanical responses of the bio-nano interface: A molecular dynamics study of graphene-coated lipid membrane

Bio-nano interfaces between biological materials and functional nanodevices are of vital importance in relevant energy and information exchange processes, which thus demand an in-depth understanding. One of the critical issues from the application viewpoint is the stability of the bio-nano hybrid under mechanical perturbations. In this work we explore mechanical responses of the interface between lipid bilayer and graphene under hydrostatic coating provides remarkable resistance to the pressure or indentation loads, We find that graphene loads, and the intercalated water layer offers additional protection. These findings are discussed based on molecular dynamics simulation results that elucidate the molecular level mechanisms, which provide a basis for the rational design of bionanotechnology- enabled aoolications such as biomedical devices and nanotheraoeutics.

Parametric Study on the Effect of Aspect Ratio of Selected Cooling Hole Geometries on the Mechanical Response of an Automobile Aluminium Alloy Wheel

Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is sparse on the effect of aspect ratio (AR) of CHs on wheels. This, work, therefore, attempts to undertake a parametric study of the effect of aspect ratio (AR) on the mechanical response of an aluminium alloy wheel with triangular, quadrilateral and oval-shaped CHs. Three-dimensional wheel models (6JX14H2ET42) with triangular, quadrilateral and oval shaped CH (each with CH area of 2229 mm2) were generated, discretized, and analyzed by FEM using Creo Elements/Pro 5.0 to determine the mechanical response at the inboard bead seat at different ARs of 1, 0.5, 0.33 and 0.25, each for quadrilateral-CH and oval-CH, at a static Radial Load of 4750 N and Inflation Pressures of 0.3 and 0.15 MPa, respectively. The study shows that the magnitude of stress and displacement is affected by shape and AR of CH. From the results, it could be established that oval-shaped-CH wheel at AR of 0.5 offers greater prospect in wheel design as it was least stressed and deformed and, that the CH combination with highest integrity was the oval-CH and quadrilateral-CH at AR of 0.5.

The mechanical response of multi-tower continuous-span suspension bridge deck pavement based on whole bridge analysis

The effect of multiple span suspension structure on the mechanical response of bridge deck pavement was studied, and finite element analysis (FEM) of stress and strain of pavement according to the bridge floor system features of super-long and high flexibility was made. Meanwhile, the FEM results were compared with those of the single span suspension structure. Three-stage analytic hierarchy process (AHP) is developed to analyze the mechanical response including whole bridge analysis, partial beams section analysis and orthotropic plate analysis. The most unfavorable load position was determined by the numerical solutions acquired from each stage to study the main mechanical index of multiple span suspension structure. The FEM results showed that the mechanical response numerical solutions by using the three-stage AHP are greater than those by simplified boundary condition, and the force condition of multiple span suspension structure is worse than that of the single span suspension structure.

Mechanical response of a tunnel subjected to strike-slip faulting processes,based on a multi-scale modeling method

The stick-slip action of strike-slip faults poses a significant threat to the safety and stability of underground structures.In this study,the north-east area of the Longmenshan fault,Sichuan,provides the geological background;the rheological characteristics of the crustal lithosphere and the nonlinear interactions between plates are described by Burger’s viscoelastic constitutive model and the friction constitutive model,respectively.A large-scale global numerical model for plate squeezing analysis is established,and the seemingly periodic stick-slip action of faults at different crust depths is simulated.For a second model at a smaller scale,a local finite element model(sub-model),the time history of displacement at a ground level location on the Longmenshan fault plane in a stick-slip action is considered as the displacement loading.The integration of these models,creating a multi-scale modeling method,is used to evaluate the crack propagation and mechanical response of a tunnel subjected to strike-slip faulting.The determinations of the recurrence interval of stick-slip action and the cracking characteristics of the tunnel are in substantial agreement with the previous field investigation and experimental results,validating the multi-scale modeling method.It can be concluded that,regardless of stratum stiffness,initial cracks first occur at the inverted arch of the tunnel in the footwall,on the squeezed side under strike-slip faulting.The smaller the stratum stiffness is,the smaller the included angle between the crack expansion and longitudinal direction of the tunnel,and the more extensive the crack expansion range.For the tunnel in a high stiffness stratum,both shear and bending failures occur on the lining under strike-slip faulting,while for that in the low stiffness stratum,only bending failure occurs on the lining.

Mechanical Response of Conductor on Round Core(CORC)Cables Under Electromagnetic Force

The conductor on round core(CORC)cables are fabricated with multilayer high-temperature superconductor tapes,which are helically wound around a circular central former.The large Lorentz force will be generated by the transport current in CORC cables under high magnetic field,which will affect the stress and strain distributions of tapes in the cables and the performance of superconducting tape.This paper establishes a two-dimensional axisymmetric model to analyze the mechanical response of CORC cables subjected to the Lorentz force and analyzes the influence of air gaps on stress and strain distributions inside the cables.The T-A method is used to calculate the distributions of current density,magnetic field and the Lorentz force in CORC cables.The mechanical response of CORC cables is analyzed by applying the Lorentz force as an external load in the mechanical model.The direction of electromagnetic force is analyzed in CORC cables with and without shielding current,and the results show that the shielding current can lead to the concentration of electromagnetic force.The maximum stress and strain occur on both sides of the superconducting tapes in the cables with shielding current.Reducing the size of air gaps can reduce the stress and strain in the superconducting layers.The analysis of mechanical response of CORC cables can play an important role in optimizing the design of CORC cables and improving transmission performance.

Research on pavement cracking possibility based on the load mechanical response

Cavities under roads are one of the main reasons for early structural damage to pavements. It is necessary to conduct a structural analysis of road sections with cavities and evaluate the possibility of pavement cracking caused by different cavity sizes. In this study, an analysis method for evaluating the possibility of pavement cracking based on the load-mechanical response is proposed.An example library of the mechanical response of asphalt concrete(AC) pavements was established by numerical simulation.Based on the tensile cracking characteristics of pavements in the mechanical response research, the tensile strain at the bottom of the AC layer was selected as the key analysis parameter. Sensitivity analysis of the tensile strain was conducted, and the main factors controlling pavement cracking were determined. A tensile strain response prediction model was established using multiple linear regression, and its reliability was verified. The cavity influence coefficient(CIC) and pavement cracking factor(PCF) were constructed to analyze the cracking possibility. The variation in PCF with the cavity size and pavement structure parameters was studied. A quantitative relationship between the depth and length of the cavity for a given PCF was obtained.This law conforms to a power function. The possibility of pavement cracking can be determined by measuring the cavity size.Compared to the existing cavity management system, the proposed method provided analysis results of the cracking possibility that were more consistent when the cavity depth was small and the length was long. The findings of this study provide new insights for evaluating the possibility of pavement cracking.

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load.The ground layers are assumed to be linear-elastic with full-stick contact between them.To solve the proposed multi-boundary problem,a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries.Based on the principle of linear-elastic superposition,the multi-boundary problem is converted into a superposition of multiple single-boundary problems.The conformal mappings of different boundaries are independent of each other,which allows the stress and displacement fields to be obtained by the sum of components from each boundary.The analytical results are validated based on numerical and in situ monitoring results.The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground;thus,it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings.Moreover,the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

Effect of Crystallization and Entropy Contribution Upon the Mechanical Response of Polymer Nano-fibers:A Steered Molecular Dynamics Study

The mechanical response of polyethylene nano-fibers with the same chain length but different chain numbers are studied by using steered molecular dynamics simulations.The shrinking or stretching forces acted on the chain ends are investigated according to the chain-end distance and temperature under isothermal or continuous warming-cooling conditions,respectively.An inflection point is found in the ForceDistance response when temperature is below 500 K.This inflection point is related to the balance between entropy force and inter-monomer interaction and it reflects the strong effect of crystallization on the mechanical response of the nano-fibers.The force at inflection point is also affected by the buckling effect due to increased stiffness when crystallization occurs.The two stages found in the Force-Temperature response and the difference between the shrinking and stretching forces indicate the hysteresis of crystallization and melting.The forces at different shrinking and stretching rates reveal the entropy contribution upon the mechanical response,indicated by the Ramachandran plot of dihedrals.The chain-conformation entropy is majorly contributed by dihedrals and is quantified by the information entropy of dihedrals,which has a highly similarity to the mechanical Force-Temperature response.The enlarged forces in multiple chains over a single chain are attributed to the enhanced dihedral-conformation entropy.Our study provides a new insight to the dynamically mechanical response of polymer nano-fibers according to the effect of crystallization and entropy contribution.

Unleashing the Potential of Unidirectional Mechanical Materials: Breakthroughs and Promising Applications

The emergence of mechanically one-way materials presents an exciting opportunity for materials science and engineering. These substances exhibit unique nonreciprocal mechanical responses, enabling them to selectively channel mechanical energy and facilitate directed sound propagation, controlled mass transport, and concentration of mechanical energy amidst random motion. This article explores the fundamentals of mechanically one-way materials, their potential applications across various industries, and the economic and environmental considerations related to their production and use.

Longitudinal mechanical response of tunnels under active normal faulting

This paper aims to clarify the mechanism of the longitudinal response of a tunnel under normal faulting via a comprehensive analysis of available experimental data and numerical simulations.Four 1 g condition model tests were reviewed and reanalysed to highlight the key characteristics of the tunnel response under normal faulting:S-shaped deformation and inverted S-shaped bending strain distribution in the longitudinal direction;the main affected zone of faulting is approximately six times the tunnel diameter to the fault plane.A threedimensional finite element model was also established and verified,followed by a sensitivity analysis of key parameters,including the fault dislocation,dip angle,tunnel rigidity and relative stiffness between the hanging wall and footwall.All results reveal that the longitudinal mechanical response under normal faulting is dominated by a combination of bending,tension,and shearing.Bending and shearing are induced by the large unbalanced rock pressure at the vault in the hanging wall and the inverted arch in the footwall;the value of unbalanced rock pressure is directly proportional to the dislocation but negatively correlated with the dip angle.Although the main part of the tunnel stays in tension,axial compressive strain exists around the fault plane when the dip angle is greater than 70 °,which may be related to the ovaling effect of the tunnel.Such an ovaling effect is caused by the compression at the cross-section of the tunnel and may lead to more complicated internal strain.

Analysis and finite element simulation for mechanical response of wheat to wind and rain loads

The morphological characteristics and stalk biomechanical properties at the dough stage of wheat were determined using the variety of wheat in the breeding process.Their mechanical responses to wind and rain loads for an individual and a group of wheat were simulated using finite element method by ANSYS.The stress and displacement of each finite element can be outputted through stress nephogram and displacement nephogram,respectively.In order to judge whether the wheat could return to its original position after deformation,elastic mechanics theory was utilized to analyze the critical load of instability under both axial rain load and transverse wind load.The large displacement situation was analyzed with large displacement elastic nonlinear theory and the numerical value was obtained by ANSYS.The results show that it is possible to apply various load types on models using ANSYS and the dynamic response can be simulated well under different rain and wind loads.The location of maximum Von Mises stress can be calculated and the variation of stress can be described clearly,which are helpful to predict the wheat lodging under wind and rain loads.