Moisture Reduction to Enhance Shock Absorber Performance Using a Combination of Eight Steps and VDI 2222 in the Motorcycle Industry

The use environment of rubber shock absorber is changeable. The degree of maintaining stable working performance in different environments is an important reference factor for selecting shock absorber. Based on the temperature condition, this paper studies the damping effect of the same type of shock absorber on the same load at different temperatures. Keep the shock absorber at a certain temperature through the temperature box, and then conduct vibration test on the load to test the performance of the shock absorber. The results show that in the range of - 50 ~ 65 ℃, the performance of the shock absorber at low or high temperature changes little compared with that at normal temperature, which will not affect the shock absorption effect of the shock absorber at all.

Full-face rider helmets are widely used these days, but the shock absorption and safety performance of them have not been discussed yet. So we examined the shock absorption performance and the safety of three full-face rider helmets (samples A, B, and C) of which the laminated constitutions of the FRP shell part were respectively different. The effect of the hybrid lamination, composed of aramid and glass fabrics, on the shock absorption performance has been discussed also. Testing was performed twice for the same impact site of a helmet hit flat and with semi-spherical anvils, according to the JIS-C shock absorption test method. The following results were obtained: The acceleration waveform measured at the forehead part of Helmet-A, which was hit on a semi-spherical anvil, behaved flatly while the part on the left side of the head behaved parabolically. In the case of Helmets-B and -C, which have an aramid fabric layer, they behaved conversely, such that a flat waveform was observed on the part on the le...

Simulation and experimental validation of vehicle dynamic characteristics for displacement-sensitive shock absorber using fluid-flow modelling

During the 2019 Spring Forecasting Experiment in NOAA’s Hazardous Weather Testbed, two NWS forecasters issued experimental probabilistic forecasts of hail, tornadoes, and severe convective wind using NSSL’s Warn-on-Forecast System (WoFS). The aim was to explore forecast skill in the time frame between severe convective watches and severe convective warnings during the peak of the spring convective season. Hourly forecasts issued during 2100–0000 UTC, valid from 0100 to 0200 UTC demonstrate how forecasts change with decreasing lead time. Across all 13 cases in this study, the descriptive outlook statistics (e.g., mean outlook area, number of contours) change slightly and the measures of outlook skill (e.g., fractions skill score, reliability) improve incrementally with decreasing lead time. WoFS updraft helicity (UH) probabilities also improve slightly and less consistently with decreasing lead time, though both the WoFS and the forecasters generated skillful forecasts throughout. Larger skill differences with lead time emerge on a case-by-case basis, illustrating cases where forecasters consistently improved upon WoFS guidance, cases where the guidance and the forecasters recognized small-scale features as lead time decreased, and cases where the forecasters issued small areas of high probabilities using guidance and observations. While forecasts generally “honed in” on the reports with slightly smaller contours and higher probabilities, increased confidence could include higher certainty that severe weather would not occur (e.g., lower probabilities). Long-range (1–5 h) WoFS UH probabilities were skillful, and where the guidance erred, forecasters could adjust for those errors and increase their forecasts’ skill as lead time decreased. Significance Statement Forecasts are often assumed to improve as an event approaches and uncertainties resolve. This work examines the evolution of experimental forecasts valid over one hour with decreasing lead time issued using the Warn-on-Forecast System (WoFS). Because of its rapidly updating ensemble data assimilation, WoFS can help forecasters understand how thunderstorm hazards may evolve in the next 0–6 h. We found slight improvements in forecast and WoFS performance as a function of lead time over the full experiment; the first forecasts issued and the initial WoFS guidance performed well at long lead times, and good performance continued as the event approached. However, individual cases varied and forecasters frequently combined raw model output with observed mesoscale features to provide skillful small-scale forecasts.

PurposeThe purpose of this paper is to describe the structure of nonlinear dampers and the dynamic equations, and nonlinear realization principles and optimize the parameters of nonlinear dampers. Using the finite element method to analyze the seismic performance of the frame structure with shock absorber.Design/methodology/approachThe nonlinear shock absorber was installed in a six-storey reinforced concrete frame structure to study its seismic performance. The main structure was designed according to the eight degree seismic fortification intensity, and the time history dynamic analysis was carried out by Abaqus finite element software. EL-Centro, Taft and Wenchuan seismic record were selected to analyze the seismic response of the structure under different magnitudes and different acceleration peaks.FindingsThrough the principle study and parameter analysis of the nonlinear shock absorber, combined with the finite element simulation results, the shock absorption performance and shock absorption effect of the nonlinear energy sink (NES) nonlinear shock absorber are given as follows: first, the damping of the NES shock absorber is satisfied, and the linear spring stiffness and nonlinear stiffness of the shock absorber are based on the relationship k1=kn×kl2, so that the spring design length is fixed, and the linear stiffness of the shock absorber can be obtained. The nonlinear shock absorber has the characteristics of high rigidity and frequency bandwidth, so that the frequency is infinitely close to the frequency of the main structure, and when the mass of the shock absorber satisfies between 0.056 and 1, a good shock absorption effect can be obtained, and the reinforced concrete with the shock absorber is obtained. The frame structure can effectively reduce the seismic response, increase the natural vibration period of the structure and reduce the damage loss of the structure. Second, the spacer and each additional shock absorber have a small difference in shock absorption effect. After the shock absorber parameters are accurately calculated, the number of installations does not affect the shock absorption effect of the structure. Therefore, the shock absorber is properly constructed and accurately calculated. Parameters can reduce costs.Originality/valueNew shock absorbers reduce earthquake-induced damage to buildings.

Monitoring of energy dissipation in hydraulic shock absorbers (in Polish) Monitorowanie rozpraszania energii w amortyzatorach hydraulicznych

The economic benefits of running a shock absorber seem evident from their growing use in oil and gas drilling operations. However, some controversy still exists over when they should be used, how to get the greatest benefit from them, and whether there are some negative effects such as hole deviation associated with the usage of some shock absorbers. Extensive experience in recent years has included results with a wide variety of shock absorber designs in the full range of hole depths and sizes. The results show that lateral stiffness of the tool, the type of spring or other energy absorption system, and tool length have a significant influence on shock absorber performance. The energy absorption system and its location in the drill string, in conjunction with the type of bottom hole assembly design, bit selection, and formation characteristics, determine whether the maximum benefits possible from the shock absorber are attained Major benefits from proper use of the appropriate shock absorber are longer bit life, higher drilling rates, longer drill-string life, reduced hazard from bending fatigue of the threaded connections in the drill string, and reduced wear on the rig equipment. These all result in a significant reduction of the overall drilling costs. Guidelines for shock absorber selection, placement in the drill string, and operating practices which yield the greatest overall benefit from the use of a shock absorber in oilfield drilling are described. Ultimately, the decision to use a shock absorber will be based on economics. Does the use of a shock absorber reduce the overall drilling cost?

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.

Application of air-bubble cushioning to improve the shock absorption performance of type I industrial helmets

Auxetic materials, known as materials with negative Poisson’s ratio (NPR), have many promising application areas. However, there are only few natural and man-made materials such as certain living bone tissues, certain rocks and minerals, polymeric honeycombs, microporous polytetrafluoroethylene (PTFE), foams, and carbon-fiber-reinforced epoxy composite laminate panels that possess this property. In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilized normal materials which follow Hooke’s law but still show the NPR properties. One of the applications is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industry workers, law enforcement and military personnel, and sports players. It is important to develop new body protectors that best combine each individual’s requirements for wearing comfort (flexible, light-weight), ease of fitting (customized), ensured protection, and cost-effectiveness. The protection pad would be made from multilayer materials and adaptive structures to achieve unique multifunctional properties such as high hardness, impact toughness, light weight, and excellent shock absorption suitable for the needs. This paper reports an integrated theoretical, computational (finite element analysis), and experimental investigation conducted for typical auxetic polymeric materials that exhibit negative Poisson’s ratio (NPR) effect. Parametric 3D CAD models of auxetic polymeric structures such as re-entrant hexagonal cells and arrowhead were developed. Then, key structural characteristics of protectors were evaluated through static analyses of FEA models. In addition, impact/shock analyses were conducted through dynamic analyses of FEA models to validate the results obtained from the static analyses. Particularly, an advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic polymeric structures. Specifically, three different materials typically used for FDM (Fused Deposition Modeling) technology such as Polylactic acid (PLA) and thermoplastic polyurethane (TPU) material (NinjaFlex® and SemiFlex®) were used for different stiffness and shock-absorption performances. The 3D printed prototypes were then tested and the results were compared with the computational prediction. The results showed that the auxetic material can be effective for body protection pads. Each structure and material had unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Particularly, auxtetic structures showed better shock absorption performance than non-auxetic ones. The mechanism for ideal input force distribution or shunting could be suggested for designing protectors using various shapes, thicknesses, and materials of auxetic materials to reduce the risk of injury.

Shock absorber is a part of the suspension system which provides comfort experience while driving. Resonance, a phenomenon where forced frequency is coinciding with the natural frequency has significant effect on the shock absorber itself. Thus, in this study, natural frequencies of the shock absorber in a 2 degree-of-freedom system were investigated using Wolfram Mathematica 11, CATIA, and ANSYS. Both theoretical and simulation study how will the resonance affect the car shock absorber. The parametric study on the performance of shock absorber also had been conducted. It is found that the failure tends to occur on coil sprung of the shock absorber before the body of the shock absorber is fail. From mathematical modelling, it can also be seen that higher vibration level occurred on un-sprung mass compare to spring mass. This is due to the weight of sprung mass which could stabilize as compared with the weight of un-sprung mass. Besides that, two natural frequencies had been obtained which are 1.0 Hz and 9.1 Hz for sprung mass and un-sprung mass respectively where the acceleration is recorded as maximum. In conclusion, ANSYS can be used to validate with theoretical results with complete model in order to match with mathematical modelling.

The impact of stochastic lead time reduction on inventory cost under order crossover

The electric shock absorber is a device that converts the kinetic energy of an oscillating object into electric energy. This kinetic energy is normally dumped in a form of thermal energy in a conventional, mechanical shock absorber. The electric shock absorber consists of a permanent magnet linear synchronous generator (PMLSG), a spring, and an electric energy accumulator. The major goal of the project is to design and analyze the operation of an electric shock absorber. In order to define the initial requirements that the electric shock absorber has to satisfy, the construction and performance of currently used shock absorbers were studied first. With respect to this study, five versions of PMLSG were analyzed qualitatively and the most suitable design was selected. The next subject was the design calculations for the chosen type of PMLSG. To determine the dimensions as well as the parameters of its magnetic and electric circuits, the calculation program was written using MATLAB. The designed PMLSG was studied under steady-state conditions to determine its electromechanical characteristics. For this purpose the mathematical model of the generator was proposed and a program was written in MATLAB that allowed calculating its output parameters under different operation conditions. The PMLSG operates practically in dynamic conditions within the whole system: generator – spring – controlled rectified – battery. The dynamic model of the entire system of the electric shock absorber was proposed and described using the voltage equilibrium equation for the electrical port and the force equilibrium equation for the mechanical port. On the basis of these equations, a block diagram was built and simulations were carried out by using MATLAB-SIMULINK. The performance of the electric shock absorber obtained from simulations was compared with mechanical parameters of the mechanical shock absorber. The conclusion obtained indicates that the electric shock absorber is able to store part of the recovered energy in the battery. However, a great part of this energy is lost in the generator resistance and in the external resistance, which is necessary to be connected to the generator output terminal in order to obtain the desire electromechanical parameters.

Test and simulation the failure characteristics of twin tube shock absorber

This paper examines issues of safety of high-altitude works, using individual protection equipment to prevent falling from a height. In particular, the paper reviews personal protective equipment - shock absorber, its dynamic characteristics and related test methods to meet the requirements of Technical Regulations 019/2011 “Safety of Individual Protection Equipment”. The paper discusses the differences between the Russian and European standards for dynamic characteristic testing of shock absorbers, even as the former are harmonized texts of the latter, and the effect of such differences on protective performance of shock absorbers and ultimately on safety of works on heights. It have been shown that tests, conducted in accordance with the Russian regulative documents for dynamic performance of the shock absorbers, entail decreasing in safety usage of such type of IPE and increasing in injuries during falls from a height. It has been defined necessity to actualize the range of the testing system of shock absorbers, and to admit its larger value that will cause increase in protective properties of shock absorbers.