Performance Of Shock Absorber Research Articles

Lightweight Design of Shock-Absorbing and Load-Bearing Components Based on 3D Printing Technology

Nowadays, the redesign of new shock-absorbing load-bearing parts has gradually gained more and more focus due to the pressure of energy, environmental protection, and people’s pursuit of high-performance (light weight, excellent shock absorption, etc.) travel tools, and the development of 3D printing technology provides the possibility to design such high-performance parts. Therefore, firstly, the strength analysis of the parts is carried out by adopting Altar Inspire software, then topology optimization design is conducted in Inspire software and, finally, direct manufacturing is carried out using Aurora 3D printers. The results show that the maximum Mises equivalent stress of the shock-absorbing load-bearing components after lightweight design is not more than the material’s yield stress of 45 MPa and the safety factor (1.5) is greater than the minimum allowable safety factor (1.2); under such kind of premise, the quality is lightened by 63.82%. Moreover, since the structure of the parts becomes a bracket structure after the lightweight design, the shock absorption performance will be greatly improved. The 3D-printed parts have a series of advantages, namely bright surface, low roughness, no obvious warpage and other defects, and good molding effect, which lays solid the foundation for the mass production of high-performance shock-absorbing load-bearing parts.

X-Shaped Structure-Based Modeling and Control for a Stable Platform with a Series Elastic Actuator

Stable platforms are widely used in many fields to keep the environment stable for the load under the influence of the motion of the craft and other carriers. However, its stability has always been an important and serious challenge for researchers. In order to further improve its shock absorption performance, a dynamic model based on the stable platform with the series elastic actuator (SEA) is established. Meanwhile, a dynamic reference trajectory based on the X-shaped structure is designed for ignorance of the beneficial nonlinearity in the fixed reference trajectory of the stable platform. In addition, a backstepping control method is proposed to accomplish stronger and faster stabilization with more robustness. Simulations are carried out, and the effectiveness of the proposed method is verified by comparative simulations with a PID controller.

Enhancement of vibration attenuation and shock absorption in composite sandwich structures with porous foams and surface patterns

In the present study, composite sandwich structures were investigated to evaluate the effects of porous foams and surface patterns on structural stability and mass reduction of the composite sandwich structures. The composite structures used in the experiments consisted of three layers; the top and bottom polycarbonate (PC) layers and the core porous foam layers. Copper, nickel, and polypropylene (PP) foams were considered in the modeling of composite structures. Laser cutting technology was applied to the top PC layers of the composite structures to realize the surface patterns. Impact hammer and mass drop tests were performed on the composite structures to investigate their vibration attenuation and shock absorption performances. Numerous combinations of composite structures were considered by varying the foam materials and layer thicknesses to determine the best configuration. Finite element method (FEM)-based simulations were conducted to verify the experimental results. The results of this study support the implementation of porous foams and surface patterns for the increase in vibration attenuation and shock absorption performance, while achieving mass reduction for various applications in the engineering field.

Shock-absorbing effect of flooring-adopted mechanical metamaterial technology and its influence on the gait and balance of older adults

ObjectiveTo elucidate the performance of a shock-absorbing floor material with a mechanical metamaterial (MM-flooring) structure and its effect on the gait and balance of older adults.MethodsThe drop-weight impact was applied...

Evaluation of the Fall Protection of Type I Industrial Helmets.

The performance of Type I industrial helmets for fall protection is not required to be tested in standardized tests. The current study analyzed the fall protection performance of Type I industrial helmets and evaluated if the use of a chin strap and the suspension system tightness have any effect on protection performance. Head impact tests were performed using an instrumented manikin. There were 12 combinations of test conditions: with or without chin strap usage, three levels of suspension system tightness, and two impact surfaces. Four representative helmet models (two basic and two advanced models) were selected for the study. Impact tests without a helmet under all other applicable test conditions were used as a control group. There were four replicates for each test condition-a total of 192 impact tests with helmets and eight impact tests for the control group. The peak acceleration and the calculated head impact criteria (HIC)were used to evaluate shock absorption performance of the helmets. The results showed that all four helmet models demonstrated excellent performance for fall protection compared to the barehead control group. The fall protection performance of the advanced helmet models was substantially better than the basic helmet models. However, the effects of the use of chin straps and suspension system tightness on the helmets' fall protection performance were statistically not significant.

Study on shock absorption performance and damage of a new staggered story isolated system

The new staggered story isolated system is developed according to the base isolated system and the mid-story isolated system. Non-linear finite element model of an eighteen stories new staggered story isolated structure is established. For a comparative analysis, the models of a base isolated structure, a mid-story isolated structure, and an aseismic structure are also established, and their shock absorption performances and damages are analyzed for comparison. The results indicate that the new staggered story isolated structure has a small seismic response, good shock absorption performance which is feasible for application. Besides, the shock absorption performance of the new staggered story isolated structure is a little worse than the base isolated structure but slightly better than the mid-story isolated structure. The bottom of core tube and the story below the frame isolated story have large acceleration response which needs to be paid more attention in design.

Mechanical properties of magneto-sensitive shear thickening fluid absorber and application potential in a vehicle

A multifunctional smart material with both shear thickening effect and magnetorheological performance was fabricated by dispersing carbonyl iron powder (CIP) particles into shear thickening fluid, the properties and application potential were tested and analysed. Firstly, the rheological properties of this type of magneto-sensitive shear thickening fluid (MSTF) was tested by a rheometer. Besides, the influence of the current, frequency and amplitude on the mechanical properties of the absorber with MSTF was studied. Finally, the damping force and the variation rules of the Cadillac shock absorber with commercial magnetorheological fluid and MSTF were tested, compared and analysed at different currents and distinct velocities. The influence of the shear thickening effect of MSTF on the damping force in the shock absorber was studied by testing the self-made MSTF and MRF with the CIP fraction from 10% to 70%. This work provided a design idea to improve the shock absorber performance.

풋댐퍼가 적용된 경량착륙장치 기반 달착륙선 모사체 개발 및 검증

In this work, we propose a lunar lander demonstrator with lightweight landing gears combined with foot-dampers to absorb landing impact loads and improve landing stability. We select an appropriate aluminum honeycomb and foot-damper model through a set of compression tests and analysis. A set of landing tests with the lunar lander demonstrator is conducted to verify the landing stability considering various ground conditions. In addition, load cells and accelerometers are installed to measure the impact load and shock acceleration on the landing gear to investigate quantitative shock absorption performance. Our test results show that the developed landing gears successfully attenuate the shock and improve landing stability, meeting the design requirements.

Analysis of energy consumption of a main machine hall for a thermal power plant with lead dampers

The lead damper is a kind of energy dissipating device with stable hysteretic performance, good shock absorption performance and simple structure. To study the lead damper damping effect in the main machine hall, the nonlinear finite element analysis software ABAQUS is adopted to analyze the seismic performance of a main machine hall with lead damper under the action of the rare earthquake and compare the elastic-plastic analysis results under the action of different seismic wave in this paper. The results show the structural seismic performance has been improved significantly, “no collapse under strong earthquake” can be achieved, A successful engineering case was provided for the application of lead damper in the damping design of main machine hall structures.

The influence of temperature on the damping characteristic of hydraulic shock absorbers

This paper presents the results of bench-tests and calculations assessing the influence of temperature on the performance of a two-pipe hydraulic shock absorber. The shock absorber prepared for the tests was cooled with dry ice to a temperature corresponding to that associated with the average winter conditions in a temperate climate. The temperature range of the shock absorber during testing was ensured via equipping it with a thermocouple and monitoring it with a thermal imaging camera. During testing, the shock absorber was subjected to kinematic forces of a selected frequency with two different, fixed displacement amplitudes. The results of the tests showed a direct correlation between the decrease of component resistance at lower temperatures. The rate of change in resistance was higher at lower temperatures. It was also found that the energy dissipated in one shock cycle decreased linearly with an increasing temperature. Finally, a method for determining the ideal use temperature of the shock absorber for the assumed operating conditions was also presented.

The elasto-plastic analysis of the structure of a main factory building by setting up the isolation device

The lead damper is a kind of energy dissipating device with stable hysteretic performance, good shock absorption performance and simple structure. To study the lead damper damping effect in the main machine hall, the nonlinear finite element analysis software ABAQUS is adopted to analyze the seismic performance of a main machine hall with lead damper under the action of the rare earthquake and compare the elastic-plastic analysis results under the action of different seismic wave in this paper. The results show the structural seismic performance has been improved significantly, “no collapse under strong earthquake” can be achieved, A successful engineering case was provided for the application of lead damper in the damping design of main machine hall structures.

Study on seismic and shock absorption performance of Yi Ci Hui stone pillar

The rigid block structure composed of multiple blocks of stones will sway during an earthquake. The rocking and rocking impact dissipates the seismic force and has good shock absorption performance. The seismic and seismic performance of Yi Ci Hui stone pillar with multi-layer block stones was studied. The results showed that: only the acceleration increases to a certain value, the rocking amplitude of the multi-layer stacked stone pillar occurs; with the continuous increase of the earthquake acceleration, the rocking amplitude of the stone pillar will rapidly decay or even be stationary. Stacking stone pillar can effectively take advantage of high compressive strength of block stone, and only produce compressive stress in the pillar root section to avoid stress failure of stone pillar. The energy reaction of the multi-layer stone pillar is mainly kinetic energy, which reaches the maximum when the stone pillar begins to shake, and then decreases rapidly. The total strain energy reaches the peak value when the stone pillar shakes, and then remains unchanged. The rocking and shaking of stacked stone pillars causes the impact of rock interface edge to dissipate seismic energy, which makes the rocking amplitude and kinetic energy of stone pillar gradually decrease, and the total strain energy is basically unchanged, which effectively plays the role of seismic shock absorption.

A structural optimization of laminated composite curved structure for an elastic shock absorber of UAV based on a novel theory

This article defines a theoretical method to the progressive failure analysis of a laminated composite curved structure for an elastic shock absorber of a UAV (Unmanned Aerial Vehicle). Based on the continuous model, the theoretical method is presented for purposes of investigating the material failure and post-failure behavior of the laminated composite curved structure. This method is derived using the Ritz method and Hashin’s failure criteria. The validity of the theoretical method is verified by comparing the results of the finite element analysis. Finally, the theoretical method is applied to optimizing a laminated composite curved structure for an elastic shock absorber of a UAV to minimize the mass and maximize the shock absorption performance. Furthermore, the shock absorption performance of the optimized elastic shock absorber is confirmed by the finite element analysis (3D explicit dynamic analysis). The optimization result allows a database to be obtained on the structural characteristics of laminated composite curved structure for aerospace applications. Consequently, it is concluded that the theoretical method is well suited to the progressive failure analysis of a laminated composite curved structure for aerospace applications due to their relative simplicity and computational efficiency.

Dynamic Response of Composite Lining Tunnel with Buffer Layer: An Analytical and Experimental Investigation

Composite lining is often designed for the mountainous tunnels in high-intensity earthquake areas. The application of the buffer layer will bring more advantages, while the shock-absorbing mechanism is still unclear currently. In this paper, based on the Fourier-Bessel series expansion method, the dynamic stress concentration factor of composite lining tunnel with buffer layer subjected to plane SV waves in the half-space is obtained. Then, the influence of geometric and mechanical parameters of the buffer layer on composite lining was systematically analyzed. Finally, the correctness of the analytical solutions is verified by series shaking table tests and numerical simulations. Results suggest that the buffer layer can play the role of “redistributing” the seismic load, and it can effectively reduce the dynamic responses of secondary lining but amplify in primary support. There is an optimal interval of the stiffness and thickness for the buffer layer. When the stiffness ratio of the buffer layer to surrounding rock is 1/10 ∼ 1/50 or the ratio of buffer layer thickness to inner diameters of secondary lining is 1/40 ∼ 1/20, the shock-absorbing performance is remarkable. The general damage observations in tests show that the crown, arch springing, and invert of composite lining in case of no buffer layer are prone to cracking under a strong earthquake. The invert of the composite lining is more susceptible to be damaged after adopting the buffer layer. In general, the analytical results were consistent with experimental and numerical results. The above study results may provide theoretical support and experimental data for the seismic design of composite lining tunnels.

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

The industrial helmet is the most used and effective personal protective equipment to reduce work-related traumatic brain injuries. The Type I industrial helmet is a basic helmet model that is commonly used in construction sites and manufacturers. The purpose of the current study was to investigate if shock absorption performance of these helmets could be improved by using an air-bubble cushioning liner to augment the helmet’s suspension system. Drop impact tests were performed using a commercial drop tower test machine according to the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I industrial helmets were utilized in the study. The effects of the air-bubble cushioning on the helmets’ shock absorption performance were evaluated by comparing the original off-the-shelf helmet samples to the helmets equipped with an air-bubble cushioning liner. The air-bubble cushioning liner (thickness 5 mm) was placed between the headform and the helmet when being tested. The impactor had a mass of 3.6 kg and was free-dropped from different heights. The maximal peak transmitted forces for each of the tests have been evaluated and compared. Our results show that the shock absorption effectiveness of the air-bubble cushioning is dependent on the magnitude of the impact force. At lower drop heights (h<1.63 m), the air-bubble cushioning liner has little effect on the transmitted impact forces, however, at higher drop heights (h⩾1.73 m) the air-bubble cushioning liner effectively reduced the peak transmitted forces. At a drop height of 1.93 m (the highest drop height tested), the air-bubble cushioning liner reduced the peak transmitted force by over 80%. Our results indicate that adding an air-bubble cushioning liner into a basic Type I industrial helmet will substantially increase shock absorption performance for large impact forces.

4D printed zero Poisson's ratio metamaterial with switching function of mechanical and vibration isolation performance

The unusual properties of mechanical metamaterials are determined by the configuration of artificial periodic structures. However, the mechanical performance of conventional metamaterials is irreversible and cannot perceive and respond to the changes in the environment. In present study, a zero Poisson's ratio metamaterial with intelligent switching mechanical properties and vibration isolation effect is proposed. Based on a 4D printing method of shape memory polymer, this metamaterial is created that can sense temperature changes and switch mechanical properties. The macroscopic deformation and the morphology change of the metamaterial during compression tests are analyzed using experimental and finite element methods. The irregular buckling distortion of the metamaterial is eliminated by cylindrical design, and controllable and adjustable local deformation and stress-strain curve are achieved based on microstructure gradient design. Subsequently, this work focused on the vibration isolation performance of metamaterials, and found fascinating shock absorption performance. Compared with traditional linear spring, this metamaterial spring can effectively reduce the vibration amplitude of certain frequency bands before reaching the resonance peak, which provides a new realization method for low-frequency vibration isolation design.

Analysis of Power Regenerative Shock Absorber in Passenger Car

In this analysis, the modelling of a regenerative shock absorber in passenger car suspension system has been studied. The purpose of the conventional shock absorber in a vehicle’s suspension system is to reduce the vibration by dissipating the energy stored in the spring as heat to the surroundings. To recover the wasted energy from damper into electrical energy an inventive regenerative shock absorber is simulated. A mechanical motion rectifier is used to convert the suspension displacement into uni-directional rotation of the generator. A quarter car Simulink model of the power regenerated shock absorber was developed and simulated in order to evaluate the amount of the power regenerated. The dynamic performance of shock absorber is integrated into suspension system where the graphs are plotted with the parameter of road profile and vehicle speed. The mathematical model achieved an overall efficiency of 60% with the average of 40 watts.

Self-Capacitance Proximity and Tactile Skin Sensor With Shock-Absorbing Structure for a Collaborative Robot

Human collaborative robots (HCRs) work in close cooperation with humans. The proximity and tactile sensors placed on the HCR surface ensure the safety of humans working with the robots. However, many of these sensors do not have a collision absorption function. In this paper, we propose a self-capacitance proximity and tactile skin sensor with a shock-absorbing structure for HCRs. We evaluated the shock absorption performance and the proximity and tactile measurements of the prototype sensors using different thicknesses of the soft layer, which acted as a shock absorber. Results confirmed that when the thickness of the soft layer increased, the shock absorption function also increased, but the contact detection sensitivity decreased. In addition, we evaluated the collision between the robot with the sensor and an object when the robot moved. The sensor could absorb the impact of the collision between the robot and the object. Furthermore, multiple sensors placed on the robotic arm could detect an object before and after making contact in real time. We proved that the proposed sensor system with the shock absorber is reliable and can be used as a proximity and tactile skin sensor for HCRs.

Damping Composites from Materials with Different Elastic Hysteresis Properties for Sandwich Shock Absorbers of Railroad Transport

The damping composites from the materials with different elastic hysteresis properties have been studied at dynamic loads and temperatures of +23°C and –40°C. A sandwich shock absorber for a rail damping element that is 14 mm in thickness from fiber-reinforced rubber composite and thermoplastic elastomer, which combines the advantages of each material, has been developed. A procedure for the choice of elastic hysteresis characteristics of sandwich shock absorbers and a mathematical model of a wagon–track multiple-mass vibration system making it possible to evaluate the applicability and performance of such shock absorbers have been proposed.

The evaluation on shock absorption performance of buffer layer around the cross section of tunnel lining

The buffer layer around the cross section of lining structure would be the most simple and effective shock absorption measure, which can cut off the transferring paths of adverse effects from surrounding rock to lining structures. Meanwhile, it can reduce the seismic action intensity and minimize the extra pressure from surrounding rock by changing seismic acting patterns. This paper presents outcomes by investigating the interaction between lining structure and surrounding rock during excitation as well as deriving influencing parameters with regard to shock absorption performances of buffer layer. Afterwards, series numerical calculations are systematically carried out with attention given to the seismic-induced deformation responses of rock-layer-lining system. Finally, an elaborated evaluation method for assessing shock absorption performance of buffer layer with an evaluation expression is proposed, which is validated by series shaking table model tests and numerical simulations. This evaluation expression would be able to guide the selection and construction of buffer layer according to the geological conditions and construction circumstances by changing geometric and material parameters. The evaluation result would have uniqueness once all the parameters are confirmed. From this expression and its derivation process, the following findings can be drawn: (1) The cross section of tunnel has the identical particular deformation pattern in each constructing phase during excitation regardless of the existence of lining structure and buffer layer, that is, the two orthogonal diagonal diameters of cross section alternatively expand and contract. (2) The geometric and material parameters simultaneously determine the shock absorption performances of buffer layer, which grows in direct proportion to geometric variables but decreases in inversely proportion to material variables. (3) When the ratio of lining inside radius to buried depth is equal to 0.2 (i.e. r0/H = 0.2), the buried depth of tunnel engineering should be the ideal position for adopting buffer layer. Meanwhile, when the ratio of buffer layer thickness to lining inside radius is equal to 0.2 (i.e. tb/r0 = 0.2), it can be confirmed the optimal thickness of buffer layer. (4) The evaluation expression of shock absorption performance is independent of seismic waveforms but involved in the excitation intensities and the destruction states of lining structure.