Performance Of Shock Absorber Research Articles

Harnessing plasticity in sequential metamaterials for ideal shock absorption.

Mechanical metamaterials exhibit interesting properties such as high stiffness at low density1-3, enhanced energy absorption3,4, shape morphing5-7, sequential deformations8-11, auxeticity12-14 and robust waveguiding15,16. Until now, metamaterial design has primarily relied on geometry, and materials nonlinearities such as viscoelasticity, fracture and plasticity have been largely left out of the design rationale. In fact, plastic deformations have been traditionally seen as a failure mode and thereby carefully avoided1,3,17,18. Here we embrace plasticity instead and discover a delicate balance between plasticity and buckling instability, which we term 'yield buckling'. We exploit yield buckling to design metamaterials that buckle sequentially in an arbitrary large sequence of steps whilst keeping a load-bearing capacity. We make use of sequential yield buckling to create metamaterials that combine stiffness and dissipation-two properties that are usually incompatible-and that can be used several times. Hence, our metamaterials exhibit superior shock-absorption performance. Our findings add plasticity to the metamaterial toolbox and make mechanical metamaterials a burgeoning technology with serious potential for mass production.

Study of Orifice Design on Oleo-Pneumatic Shock Absorber

Aircraft oil-strut shock absorbers rely on orifice designs to control fluid flow and optimize damping performance. However, the complex nature of cavitating flows poses significant challenges in predicting the influence of orifice geometry on energy dissipation and system reliability. This study presents a comprehensive computational fluid dynamics (CFD) analysis of the effects of circular, rectangular, semicircular, and cutback orifice profiles on the internal flow characteristics and damping behavior of oleo-pneumatic shock absorbers. High-fidelity simulations reveal that the rectangular orifice generates higher damping pressures and velocity magnitude than those generated by others designs, while the semicircular shape reduces cavitation inception and exhibits a more gradual pressure recovery. Furthermore, the study highlights the importance of considering both geometric and thermodynamic factors in the design and analysis of cavitating flow systems, as liquid properties and vapor pressure significantly impact bubble growth and collapse behavior. Increasing the orifice length had a negligible impact on damping but moderately raised orifice velocities. This research provides valuable insights for optimizing shock absorber performance across a range of operating conditions, ultimately enhancing vehicle safety and passenger comfort.

Non-geodesic winding design method for the composite shell of unequal-pole-hole solid rocket motor

Advanced composite materials have the advantages of high specific strength, high specific modulus, good fatigue resistance, good shock absorption performance, and strong designability. They are widely used in the fields of national defense science and technology and civil engineering. To make a more accurate winding design of the composite shell of the non-equidistant solid rocket motor, based on the ANSYS ACP composite structure design and analysis software, this paper uses the cubic spline function method to design the fiber winding thickness of the shell head section for a solid rocket motor. The Runge-Kutta method is used to calculate the changing winding angle of the non-geodesic line, and the changing winding angle and winding thickness on the head are simulated based on the look-up table interpolation table module in ACP. Finally, the mechanical properties of the designed shell under certain internal pressure are simulated and analyzed. Through the simulation analysis of the designed engine model, it is found that the connection between the front head and the barrel section is a weak profit, and the follow-up study should reinforce this area.

Testing the shock protection performance of Type I construction helmets using impactors of different masses.

Wearing protective helmets is an important prevention strategy to reduce work-related traumatic brain injuries. The existing standardized testing systems are used for quality control and do not provide a quantitative measure of the helmet performance. To analyze the failure characterizations of Type I industrial helmets and develop a generalized approach to quantify the shock absorption performance of Type I industrial helmets based on the existing standardized setups. A representative basic Type I construction helmet model was selected for the study. Top impact tests were performed on the helmets at different drop heights using two different impactor masses (3.6 and 5.0 kg). When the helmets were impacted with potential impact energies smaller than the critical potential impact energy values, there was a consistent relationship between the peak impact force and the potential impact energy. When the helmets were impacted under potential impact energies greater than the critical potential impact energy values, the peak impact forces increased steeply with increasing potential impact energy. A concept of safety margin for construction helmets based on potential impact energy was introduced to quantify the helmets' shock absorption performance. The proposed method will help helmet manufacturers improve their product quality.

Directional damping design of viscoelastic composites via topology optimization

Design of architected functional materials that possess desired damping performance is a topic of great interest in both academic research and industrial applications. This study investigates the concept of ‘directional damping’ for viscoelastic composites and develops a topology optimization framework to achieve directional damping design. Microstructures with both load-bearing capacity and dominant damping in the prescribed direction are obtained by maximizing the loss factor while imposing stiffness constraints. An optimized directional damping microstructure design exhibits a loss factor 1.8 times higher than the isotropic design in the prescribed direction. It is found that the optimized configurations with curved viscoelastic strips are similar to wavy ‘suture’ lines in the beaks of woodpeckers, which possess outstanding energy absorption performance. We have also verified the superiority of the directional damping design through numerical simulations and experiments of the microstructured composites. The experiment results show significant reduction of peak response for the directional damping design compared to the isotropic counterpart. To demonstrate the application potential of the optimized unit cell microstructures, a novel conceptual airless tire that exhibits improved stiffness and shock absorption performance is designed and validated through both numerical simulations and experiments.

Unsteady Multiphase Simulation of Oleo-Pneumatic Shock Absorber Flow

The internal flow in oleo-pneumatic shock absorbers is a complex multiphysics problem combining the interaction between highly unsteady turbulent flow and multiphase mixing, among other effects. The aim is to present a validated simulation methodology that facilitates shock absorber performance prediction by capturing the dominant internal flow physics. This is achieved by simulating a drop test of approximately 1 tonne with an initial contact vertical speed of 2.7 m/s, corresponding to a light jet. The flow field solver is ANSYS Fluent, using an unsteady two-dimensional axisymmetric multiphase setup with a time-varying inlet velocity boundary condition corresponding to the stroke rate of the shock absorber piston. The stroke rate is calculated using a two-equation dynamic system model of the shock absorber under the applied loading. The simulation is validated against experimental measurements of the total force on the shock absorber during the stroke, in addition to standard physical checks. The flow field analysis focuses on multiphase mixing and its influence on the turbulent free shear layer and recirculating flow. A mixing index approach is suggested to facilitate systematically quantifying the mixing process and identifying the distinct stages of the interaction. It is found that gas–oil interaction has a significant impact on the flow development in the shock absorber’s upper chamber, where strong mixing leads to a periodic stream of small gas bubbles being fed into the jet’s shear layer from larger bubbles in recirculation zones, most notably in the corner between the orifice plate and outer shock absorber wall.

Experimental study on shock isolation of metal rubber-disc spring composite shock absorber under different shock excitation

Due to the instability and aiming accuracy of the onboard laser emission system cannot meet the requirements of its work tasks, it is necessary to carry out vibration isolation optimization design for the laser emission system. This paper designs a metal rubber-disc spring composite shock absorber and conducts relevant experimental research on the shock isolation performance of the metal rubber-disc spring composite shock absorber. The shock isolation performance tests of the shock absorber under different shock excitation conditions with pendulum heights of 300 mm, 600 mm, 900 mm, and 1200 mm were carried out respectively. Through the experiments, it was found that when the pendulum height is 300 mm, the shock isolation effect of the metal rubber-disc spring composite shock absorber is the best, and the shock isolation rate is above 95%.

Study on seismic performance of nanometakaolin-reinforced fluororubber sector damper (NFSD)

In order to improve the mechanical performance of the core energy-dissipating material of the viscoelastic damper, a novel Nanometakaolin-reinforced Fluororubber Sector Damper (NFSD) is proposed for providing a strong guarantee for the seismic safety of the structure joints subjected to seismic earthquake. Firstly, in order to systematically study the shock absorption performance of NFSD, the core energy dissipation material(nano metakaolin reinforced fluororubber composite) of NFSD is prepared by melt blending method, and the vulcanization performance and microscopic mechanism of the nano composite are analyzed by vulcanization test and X-ray diffraction test. Secondly, the nanocomposite material is used as the core energy dissipation material, and NFSD based on nano reinforced fluororubber is proposed. Finally, the dynamic characteristics of NFSD and the structural seismic performance of NFSD controlled reinforced concrete (RC) frames are studied using refined finite element simulation methods. The research results indicate that 20 phr NMK increase the maximum torque MH of FKM by 20 %, while also shortening the scorching time t10 by 0.28 min. It means greatly improving the vulcanization performance of FKM. Compared to uncontrolled structures, NFSD reduces the peak displacement, interstory displacement angle, and maximum vertex acceleration of the 4-story RC structure by 16.2 %−67.4 %, 12.4 %−64.6 %, and 16.8 %−43 %, respectively. NFSD possesses excellent seismic absorption performance.

Analysis of shock absorption performance of a new staggered story isolation structure under far-field long-period ground motions

The new staggered story isolation (NSSI) is a new type of isolation method developed based on base isolation (BI) and mid-story isolation (MSI). Different from ordinary ground motions, far-field long-period ground motions have the characteristics of long period, long duration, and rich low-frequency components, which will have adverse effects on structures with relatively large periods of isolation, which need to be discussed in depth. Based on this, this paper establishes a 16-story frame core tube structure, under rare earthquakes, adopts NSSI, and inputs 7 ordinary ground motions (OGM), 7 far-field anharmonic-like ground motions (FAGM), and 7 far-field harmonic-like ground motions (FHGM), the latter two are collectively referred to as far-field long-period ground motions (FLGM). The seismic response results are obtained through simulation, and the shock absorption performance is compared with non-isolated, BI, and MSI. Combined isolation is proposed, and its displacement-limiting effect under FLGM is discussed. The results show that the seismic responses of various structures under FLGM are much larger than those of OGM; the NSSI structure has better overall shock absorption performance and better safety performance under FLGM; The Combined isolation has a good displacement limiting effect under various ground motions, especially for FHGM, the displacement limiting effect is the best.

Cause–effect relationship between model parameters and damping performance of hydraulic shock absorbers

Despite long-term research and development of modern shock absorbers, the effect of variations of several crucial material and model parameters still remains dubious. The goal of this work is therefore a study of the changes of shock absorber dynamics with respect to typical parameter ranges in a realistic model. We study the impact of shim properties, as well as geometric features such as discharge coefficients and bleed orifice cross section. We derive cause–effect relationships by nonlinear parameter fitting of the differential equations of the model and show digressive and progressive quadratic damping curves for shim number and thickness, sharp exponential curves for discharge coefficients, and leakage width, as well as a linear decrease of damping properties with bleed orifice area. Temperature increase affecting material properties, such as density and viscosity of the mineral oil, is found to have a mostly linear relationship with damping and pressure losses. Our results are not only significant for the general understanding of shock absorber dynamics, but also serve as a guidance for the development of specific models by following the proposed methodology.

Multi-objective design and optimization of high cushioning bionic shoe midsole under limited thickness of forefoot

To enhance the shock-absorbing performance of the midsole in conditions where thickness is limited, particularly in the forefoot region, this paper presents a novel design inspired by the structure and material assembly characteristics of ostrich metatarsophalangeal joints and toe pads. The shock-absorbing performance of the bionic unit was validated through finite element simulations and experimental testing using 3D-printed samples. In order to unravel the underlying mechanisms that enhance the cushioning performance, optimization factors for the forefoot bionic cushioning unit were determined based on the cushioning mechanism. The influence of the cantilever angle (La), cantilever taper (Lo), cantilever spacing (L3), thickness of the elastic energy-absorbing component (L4), and selected materials on the cushioning performance was discussed. The results demonstrate that with the configuration of La:Lo:L3:L4 = 60°:0.6:9 mm:3 mm and the outer frame material to elastic energy-absorbing component material ratio of T-4:T-2, compared to the non-optimized unit, the peak negative acceleration of the forefoot bionic unit has been reduced by 32.64%.Based on the optimization results, the production of the bionic cushioning sports shoes and the control shoes was completed. Finally, human wear experiments have shown that the bionic shoes exhibit a 23.7% to 29.8% increase in impact absorption compared to control shoes.

Evaluation of Mechanical Performance of a New Disc Spring-Cable Counter Pressure Shock Absorber

Mechanical performance evaluation of a new disc spring-cable counter pressure shock absorber is focused on in this study. The proposed shock absorber is always in a compressive working state with energy dissipation capacity under both tension and compression loadings. The design formulas of its axial bearing capacity, vertical stiffness, deformation energy of the shock absorber were derived, and the corresponding specific design process was provided in detail. Experimental and numerical investigations of the mechanical performance were conducted under static and dynamic loadings. The parameters influencing the laws of the mechanical performance of the shock absorber, including loading frequency, pre-compression deformation and loading amplitude, were investigated. The rationality of the proposed shock absorber was firstly verified through comparative analysis using experimental, numerical and theoretical calculations. The shock absorber with a friction coefficient of 0.005 between disc springs, and a friction coefficient of 0.3 between the disc spring and cover plate has the smallest error between experiment and theory for the flattening force. The bearing capacity of the shock absorber exhibits a linear relationship with the loading displacement in static loading. In dynamic loading, however, the bearing capacity shows a trend of slow growth followed by rapid growth. The energy dissipation capacity of the shock absorber shows an increase with the increase of loading displacement. The minimum equivalent damping ratio of all of the dynamic test cases is 7%, with a maximum up to 15.3%. Under the same loading frequency, the equivalent stiffness and equivalent damping ratio have a linear amplification trend with the increase of pre-compression deformation, and the maximum increase of equivalent stiffness is equal to 41.37%. Under the same loading frequency and pre-compression deformation, the energy consumption capacity can be improved by increasing the loading amplitude.

EXPERIMENTAL STUDY OF THE PERFORMANCE CHARACTERISTICS OF SHOCK ABSORBERS

The article discusses the methodology for determining the performance characteristics of Toyota Prius 20 shock absorbers. The study was conducted using a stand for the diagnosis of shock absorbers developed by the Department of Road Transport of INRTU (Irkutsk National Research Technical University). Tests were carried out for five front suspension shock absorbers, one – a new serviceable shock absorber, the rest – shock absorbers that were previously in operation. The experimental dependences of the change in the resistance force of the shock absorber on the speed of movement of its rod are analyzed. The level of operational characteristics of the shock absorber under study was determined by comparing the obtained parameters with the parameters of the new shock absorber.
 The results of experimental studies are presented in the form of operational characteristics of tested shock absorbers and indicators that determine the level of operational characteristics of shock absorbers. The developed methods and the equipment implementing them make it possible to determine the functional dependencies and the level of performance of shock absorbers that were in the operating conditions of the vehicle.

Responses of SDOF Structures With SPIS-<b>Ⅱ</b> Dampers Under Random Seismic Excitation

A closed-form solution of response of SDOF structure with SPIS-II damper subjected to seismic excitation modeled by Clough-Pezien spectrum is proposed, and the shock absorption performance and influencing factors of that system are studied based on the proposed method. Firstly, the equation of motion of SPIS-II damper is established, and the unified expression of the structural response frequency domain solution such as structural displacement and inertial output force are obtained. Secondly, based on the rational expression decomposition and residue theorem, quadratic quadrature equations of frequency response eigenvalue function and Clough-Pezien spectrum are obtained respectively, and then quadratic quadrature equations of structural response power spectrum are induced. Thirdly, concise closed-form solutions of the 0 ~ 2 order spectral moments of the structural response are acquired. The proposed method and the virtual excitation method are used to analyze a case respectively, which verifies the correctness of the proposed method. Finally, the proposed method is used to analyze the influence of the parameters of inertia capacity on the seismic performance of the structure. The research shows that the response solution obtained by the method in this paper is a closed-form solution, which is better than the virtual excitation method in terms of computational efficiency and computational accuracy; when <i>μ</i>_<i>ω</i>unchanged, the damping performance is enhanced with the increasing of <i>μ</i>_<i>m</i>and <i>μ</i>_<i>ξ</i>; when <i>μ</i>_<i>ω</i>=1, the damping performance is improved to the greatest.

Design and test of lateral interconnected hydro-pneumatic ISD suspension

Aim to balance the ride comfort and handling stability of vehicles and improve suspension performance, this paper presents a novel lateral interconnected hydro-pneumatic “inerter-spring-damper” (ISD) suspension integrating a hydro-pneumatic suspension and a fluid inerter, which realizes the lateral connection of the suspension through the inerter. The equivalent mathematical model of the lateral interconnected ISD suspension is established; the 15-degree-of-freedom (DOF) model of the vehicle is built in AMESim, and the key parameters are optimized by genetic algorithm. The response characteristics of the novel hydro-pneumatic ISD suspension and traditional hydro-pneumatic suspension under pulse and random input are comparatively analyzed. The lateral interconnected hydro-pneumatic ISD suspension prototype is developed and tested on the bench. The simulation and test results prove that the proposed new suspension structure has a more effective shock absorption performance than the traditional hydro-pneumatic suspension. Overall, the novel hydro-pneumatic ISD suspension better consider to the ride comfort and handling stability, and the structure is simple, compact, and easy to deploy on practical vehicles.

An experimental analysis of component contributions to shock absorption performance in third generation sport artificial turf

The increasing use of artificial turf across all levels of sports play has been hypothesized to contribute to an increase in athlete injuries. Current testing standards evaluate the shock absorbing performance of artificial turf surfaces through a single measure of acceleration after a drop test impact. However, these standards focus on the performance of the aggregate turf system, thereby neglecting the component-level contributions of the shock pad, carpet, and infill constituents. The purpose of this study was to explore a novel testing methodology that has the potential to isolate first-order and second-order contributions of components to total system performance. Various subsystems of the traditional, three layer artificial turf were treated as energy absorbing surfaces. A series of no-fatigue and fatigue tests were performed using a custom-built apparatus to characterize each energy absorbing surface at five different drop heights. During no-fatigue testing, it was found that the complete three-layer system outperformed all subsystems by mitigating resultant acceleration and force compared to the baseline. However, any energy absorbing subsystem that contained rubber infill outperformed any subsystem that included shock pad, the designated energy dissipating layer in third generation artificial turf. For fatigue testing, it was observed that energy absorbing surfaces began to deteriorate in as few as 20 impacts. In comparison to existing standards, the inclusion of a second data acquisition instrument yielded more accurate calculations of shock absorption. By capturing an input and output measurement during the impact, calculation of the surface’s characteristic transfer function is attainable and therefore, more information in gleaned from the impact test. Additional research is required to be able to deploy this testing methodology on-site, with fully installed artificial turf systems.

Simulation research on the energy dissipation and shock absorption performance of a swing column device based on fuzzy control

Simulation research on the energy dissipation and shock absorption performance of a swing column device based on fuzzy control

Identification of Structural Damage and Damping Performance of a Mega-Subcontrolled Structural System (MSCSS) Subjected to Seismic Action

Due to multiple degrees of freedom, evaluating high-rise buildings’ seismic safety under unpredictable seismic excitations is difficult. To address the issue that the damage mechanism of a mega-subcontrolled structural system (MSCSS) has not yet been studied, this paper employs ABAQUS software with strong nonlinear analysis capabilities to analyze the nonlinear elastic—plastic time history of an MSCSS, analyze structural damage to the MSCSS structure, reveal the internal energy dissipation mechanism of the MSCSS, and evaluate the damping performance of the MSCSS structure. This work presents a novel and optimized MSCSS structure equipped with SPSW that improves the system’s seismic performance. First, a refined finite element model of the MSCSS is established, and the impact of vigorous seismic excitations on the damage to the MSCSS structure is considered. The MSCSS structure’s vulnerable parts are then summarized using stress nephograms and residual stresses. Finally, the favorable damping performance of the structure reveals that the newly proposed structure has good shock absorption performance based on an analysis of the energy dissipation, time history, and interstory drift of the MSCSS. This paper’s research findings elaborate the structural damage trend in MSCSS structures, which can serve as a theoretical foundation for MSCSS structure damage identification.

Preparation and Properties of HGBTPU Composite Foam for Football Protection

Football is a very dangerous sport. In order to reduce the injury of athletes, we must have corresponding protective articles, and the materials used are very important. Foam material has attracted the attention of all circles for its light weight, high strength, strong absorption impact load, and good heat insulation performance. However, the mechanical properties of foam materials will decrease with the decrease of density, which limits their application in sports, especially in some sports occasions, such as motorcycle competition, football, and other sports protection. In this paper, HGB/TPU foam materials are mainly studied. The material not only has good shock absorption performance but also has light weight and good mechanical properties. It can be used as protective equipment for football. In this paper, HGB/TPU composite foam materials were prepared by extrusion foaming method using TPU and HGB as raw materials. The effects of HGB surface modification, foaming agent content, and HGB content on the cellular structure and mechanical properties of composite foams were also investigated. The experimental results show that when the foaming method is extrusion foaming, the content of HGB is 3% and the content of foaming agent is 1.5%. It has better resistance to external forces, which helps to protect athletes from serious injuries.

Lightweight and tough multilayered composite based on poly(aryl ether nitrile)/carbon fiber cloth for electromagnetic interference shielding

Electromagnetic interference (EMI) shielding materials are of vital importance in solving increasingly serious electromagnetic pollution. Currently, metal-based EMI shielding materials (ESMs) are ubiquitously used, however, their drawbacks of high density, low corrosion resistance, and poor flexibility restrict their application scenarios. By contrast, polymer-based composite materials have superior properties such as light weight, great shock absorption performance, and high corrosion resistance, which makes them promising electromagnetic interference shielding materials. In this work, an asymmetric network of the impedance matching layer and conductive shielding layer is constructed by coupling carbon fiber cloth (CFC) with magnetic porous poly(aryl ether nitrile) (PEN) polymer composite. Scanning electron microscopy confirms the alternating layered structure of the composites and the porous structure of the polymer layer. The unique designed composites achieve the highest EMI total shielding effectiveness (SET) of 37.76 dB and absorption shielding effectiveness (SEA) of 35.33 dB, which represents the successful preparation of a type of EMI material following an absorption-dominated mechanism. The CFC-3/PEN-Fe3O4 @PEI-25 demonstrates a satisfying EMI-SE/density/thickness (SSE/t) value of 543 dB·cm2·g−1, higher than most porous polymer-based EMI composites currently. In addition, the mechanical strength of composites is enhanced due to the unique alternating multilayered structure, with the highest tensile strength of 39.03 MPa, which is much higher than the obtained porous PEN membranes via the non-solvent induced phase separation (NIPs) method. This work proposes a novel approach to the construction of lightweight and resistant to secondary contamination ESMs with high performance, exerting enormous potential for wide application.