Cushion System Research Articles

Contaminant Trasportation of Cd<sup>2+</sup> in the Cushion System of the Municipal Waste Landfill

The cushion systems with low leakage performance are usually utilized in the municipal solid waste landfills to prevent the contaminants of the leachate from polluting the groundwater and soil beneath the landfill. Even there are the rigorous demands in related specifications in China and other countries all over the world for the design of the cushion system in the landfill. Pollution of the groundwater and the soil beneath the landfill still occurred in a large number of rubbish landfills because of the seepage. To investigate the seepage rate of the Cd2+ in the cushion systems, the minimum requirements for the design of the cushion systems are summarized according to the provisions of China and US. Comparative studies using 1-dimensional migration model are performed to investigate the seepage performance of the cushion systems consisting of geomembrance (GM) and compacted clay layer (CCL) sastifying the related minimum design demands. It could be concluded that the cushion system designed according to the minimum demands of China provide better anti-leakage performance, while that of US perform the lower. Finally, some advices for the releavent design standards are suggested according to the analyses.

Development and evaluation of a new contoured cushion system with an optimized normalization algorithm.

Prevention of pressure sores remains a significant problem confronting spinal cord injury patients and the elderly with limited mobility. One vital aspect of this subject concerns the development of cushions to decrease pressure ulcers for seated patients, particularly those bound by wheelchairs. Here, we present a novel cushion system that employs interface pressure distribution between the cushion and the buttocks to design custom contoured foam cushion. An optimized normalization algorithm was proposed, with which interface pressure distribution was transformed into the carving depth of foam cushions according to the biomechanical characteristics of the foam. The shape and pressure-relief performance of the custom contoured foam cushions was investigated. The outcomes showed that the contoured shape of personalized cushion matched the buttock contour very well. Moreover, the custom contoured cushion could alleviate pressure under buttocks and increase subjective comfort and stability significantly. Furthermore, the fabricating method not only decreased the unit production cost but also simplified the procedure for manufacturing. All in all, this prototype seat cushion would be an effective and economical way to prevent pressure ulcers.

Characteristic verification and parameter optimization of airbags cushion system for airborne vehicle

The major methods to investigate the airbags cushion system are experimental method, thermodynamic method and finite element method (FEM). Airbags cushion systems are very complicated and very difficult to be investigated thoroughly by such methods. For experimental method, it is nearly impossible to completely analyze and optimize the cushion characteristics of airbags of airborne vehicle because of charge issue, safety concern and time constraint. Thermodynamic method fails to take the non-linear effects of large airbag deformation and varied contact conditions into consideration. For finite element method, the FE model is usually complicated and the calculation takes tens of hours of CPU time. As a result, the optimization of the design based on a nonlinear model is very difficult by traditional iterative approach method. In this paper, a model based on FEM and control volume method is proposed to simulate landing cushion process of airborne vehicle with airbags cushion system in order to analyze and optimize the parameters in airbags cushion system. At first, the performance of airbags cushion system model is verified experimentally. In airdrop test, accelerometers are fixed in 4 test points distributed over engine mount, top, bottom and side armor plate of hull to obtain acceleration curves with time. The simulation results are obtained under the same conditions of the airdrop test and the simulation results agree very well with the experimental results, which indicate the established model is valid for further optimization. To optimize the parameters of airbags, equivalent response model based on Latin Hypercube DOE and radial basis function is employed instead of the complex finite element model. Then the optimal results based on equivalent response model are obtained using simulated annealing algorithm. After optimization, the maximal acceleration of airborne vehicle landing reduces 19.83%, while the energy absorption by airbags increases 7.85%. The performance of the airbags cushion system thus is largely improved through optimization, which indicates the proposed method has the capability of solving the parameter optimization problem of airbags cushion system for airborne vehicle.

Impact Responses of Composite Cushioning System considering Critical Component with Simply Supported Beam Type

In some microelectronic products, one or several components can be idealized as simply supported beam type and viewed as vulnerable elements or critical component due to the fact that they are destroyed easily under impact loadings. The composite cushioning structure made of expanded polyethylene (EPE), and expanded polystyrene (EPS) was utilized to protect the vulnerable elements against impact loadings during transportation. The vibration equations of composite cushioning system were deducted and virtual mass method was applied to predict impact behavior of critical component. Numerical results indicate that virtual mass method is appropriate for computing impact response of composite cushioning system with vulnerable element of simply supported beam type, which is affirmed by the fact that the impact responses of structure element in terms of velocity- and displacement-time curves are almost unchanged when virtual mass is smaller than a certain value. The results in this paper make it possible for installation of packaging optimization design.

ECushion: A Textile Pressure Sensor Array Design and Calibration for Sitting Posture Analysis

Sitting posture analysis is widely applied in many daily applications in biomedical, education, and health care domains. It is interesting to monitor sitting postures in an economic and comfortable manner. Accordingly, we present a textile-based sensing system, called Smart Cushion, which analyzes the sitting posture of human being accurately and non-invasively. First, we introduce the electrical textile sensor and its electrical characteristics, such as offset, scaling, crosstalk, and rotation. Second, we present the design and implementation of the Smart Cushion system. Several effective techniques have been proposed to improve the recognition rate of sitting postures, including sensor calibration, data representation, and dynamic time warping-based classification. Last, our experimental results show that the recognition rate of our Smart Cushion system is in excess of 85.9%.

A NEW CUSTOM-CONTOURED CUSHION SYSTEM BASED ON FINITE ELEMENT MODELING PREDICTION

High internal stress in the deep tissues adjacent to bony prominences can cause deep tissue injuries. Therefore, internal stress in the soft tissue should be considered when the performance of anti-decubitus cushions is evaluated during cushion design. This paper reports on a custom-contoured cushion (CCC) system incorporated with a three-dimensional (3D) slice subject-specific finite element (FE) model to investigate the internal stress distribution in the soft tissues. This stress distribution was used to transform the interface pressure into the carving depth of the fabricated cushions based on the biomechanical characteristics of the cushion materials. The internal stress in the soft tissues was investigated using an FE model of buttocks and cushion made from three cushion materials. The cushion design was optimized according to the properties of the material. The simulated interface stress between the buttocks and the cushion (18 kPa) was consistent with the measured interface pressure of the CCC (17.1 kPa). The 3D FE model predicted the internal stress and displacement of the soft tissues and cushion. Additionally, it efficiently optimized the selection of cushion material. Fifty subjects (25 subjects with spinal cord injuries (SCI) and 25 healthy subjects) were recruited to investigate the interface pressure and perform subjective comfort evaluation. The CCC decreased the interface pressure under the buttocks and simultaneously increased the subjective comfort and stability. The effectiveness of the cushion materials was predicted by the CCC system, which also validated the clinical performance of decreasing interface pressure.

Nonlinear Dynamic Analysis of Series Cushioning System Made with Expanded Polyethylene and Corrugated Paperboard

Based on the constitutive models of expanded polyethylene (EPE) and C-flute corrugated paperboard (CCP), the drop impact model for expanded polyethylene in series with CCP was established to consider the effect of cushioning action for CCP box. A numerical procedure was adopted for the optimization of the product packaging system by considering the action of the corrugated paperboard box. Then the optimal results were obtained and compared without considering the effect of CCP. Finally, the calculation reliability was proved by the comparison between calculated results and experimental data.

Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion

A dynamic model is proposed for a polymer foam-based nonlinear cushioning system. An accurate analytical solution for the nonlinear free vibration of the system is derived by applying He's variational iteration method, and conditions for resonance are obtained, which should be avoided in the cushioning design.

Virtual Mass Method for Solution of Dynamic Response of Composite Cushion Packaging System

A composite package cushioning system consists of multiple layers of cushioning materials in series. Such composite cushioning systems will enhance the protection capability to the packaged products. However, the dynamic analysis of the composite cushioning system becomes more difficult because of the strong nonlinear characteristics of cushioning materials. To overcome the difficulty in calculation, the method of virtual mass is proposed to form the system equations of motion as a set of multidimensional ordinary differential equations so that the Runge–Kutta method can be applied to obtain the numerical solution of the system response. The rationale of the method is shown both analytically and numerically by assessing the reliability of the virtual mass method. For a specific composite cushioning system consisting of two layers of expanded polystyrene (EPS) and expanded polyethylene (EPE) materials, experiments were carried out first for each material to obtain the stress–strain behaviours under both static and dynamic loadings. On the basis of these data, the stress–strain constitutive models were developed for EPS and EPE. Then, experiments were conducted for the composite cushioning system under different system parameters, and the measured data are compared with the analytical results using the method of virtual mass. The agreement between the analytical and the experimental results substantiates the accuracy of the proposed virtual mass method. Copyright © 2012 John Wiley & Sons, Ltd.

Modeling and simulation of air cushion vehicle 6-DOF maneuverability

Due to the movement complexity of air cushion vehicle, so far the research has been focused on 4DOF motion, but the 4-DOF motion equation is difficult to reflect the real movement characteristics of air cushion vehicle. In this paper, the water surface deformation under air cushion was obtained on the basis of linear wave theory, the lift fan - air duct- skirt – air cushion dynamic balancing cushion system was obtained according to the flow balance principle, at last, the 6-DOF motion model was established according to Newton’s momentum and moment of momentum theorem, and the results of movement simulation was obtained. The simulation results show that the motion model is rational, The motion model has been successfully applied to a certain type of steering simulator.

Modeling the Dropping-Induced Failure of Nonlinear Cushioning System

Modeling the Dropping-Induced Failure of Nonlinear Cushioning System

Simulation Analysis of Light Off-Road Vehicle's Body Frame during Airdropping

A guide line of the vehicles' performance during impact is given, and a design of airdrop cushion system for all the off-Road Vehicles is established in this paper. Based the software of ANSYS, it does simulation analysis for the several blue prints of the beehive cushion which are used in the practice.

Divisibility Forecast of Air Cushion Vehicle’s Motion in Wave

This article will use the wave making theory of uniform pressure side to calculate the amphibious air cushion wave. Moreover, the composited outside wave establishes the new wave that closer to the practical hull bottom wave. At the same time, utilize the flow continuity equation to build the air cushion system then to set up the perfect mathematical model of amphibious air cushion with six variances operation. In addition, forecast the divisibility of amphibious air cushion motion in wave. The forecast result can effectively affect the basic motion characteristic of the hovercraft. The simulation result can use for the deeper research of motor function for the hovercraft operation, the debugging and optimization of the control system.

Dropping damage evaluation for a hyperbolic tangent cushioning system with a critical component

A new concept of dropping damage boundary surface is proposed to evaluate the dropping damage of a critical component for a hyperbolic tangent nonlinear packaging system. A novel dynamic model is established to analyze the effect of three key coordinate parameters, i.e., the non-dimensional dropping shock velocity, the frequency parameter ratio and the defined system parameter, on dropping damage potential. An experiment, which showed good agreement, was conducted to verify the theory proposed.

Evaluation of Patient Immobilization for Liver SBRT

To evaluate intra-fraction motion during liver stereotactic body radiation therapy (SBRT) for patients immobilized in a dual vacuum cushion system, with residual setup errors determined by kilovoltage (kV) cone-beam computed tomography (CBCT) and corrected in 6 degrees of freedom (DoF) by a robotic couch.

The Damage Boundary Curve of the Suspension Packaging System under Rectangular Pulse

The geometric nonlinear dimensionless dynamical equations of suspension spring cushioning packaging system were established and a new concept of damage boundary curves of the system was developed under the action of rectangular pulse. Considering the angle of the suspension spring ,a three-dimension damage boundary curve is obtained.The mathematic results of the equation are calculated by using the four steps Runge-Kutta method. Studies have shown that the dimensionless pulse peak, the angle of suspension spring and the damping ratio of the system can affect the safe region, and that increasing damping can enlarge the safe region of the system. The shock of the packed product can reduce by adjusting the parameters of the system properly. These results have important application value in design of the suspension cushioning system.

ETFE foil spring cushion structure and its analytical method

The traditional Ethylene Tetra Fluoro Ethylene (ETFE) foil cushion is in the form of air cushion, whose structural stiffness is offered by the inner air pressure. Because the air supply and control systems are needed, air cushion structures cost extra energy and need much maintenance. In order to overcome the shortcomings of air cushion, the ETFE foil spring cushion that uses a spring to take the place of air pressure is developed in this paper. At first, the analytical method for shape finding analysis and stress analysis of the spring cushion is described in the paper. A numerical example is shown by means of the software package ANSYS and the suggested method so as to verify the validity of the method. Then, a model experiment on the ETFE foil spring cushion is carried out. In the loading test, the compression of spring is recorded and the experimental results are compared with the analytical results. At the end of the paper, an experimental hall using both ETFE foil air cushion units and spring cushion units as its roof structure is introduced. Through the construction and daily use of the experimental hall, the spring cushion system shows advantages such as easier construction, needing no air supply and control equipments, no running energy and little maintenance compared with the air cushion system.

Dynamic Modeling of Intelligent Air-Cushion Tracked Vehicle for Swamp Peat

Modeling of the dynamic behavior and motion are renewed interest in the improved tractive performance of an intelligent air-cushion tracked vehicle (IACTV). This paper presents a new dynamical model for the forces on the developed small scale intelligent air-cushion tracked vehicle moving over swamp peat. The air cushion system partially supports the 25 % of vehicle total weight in order to make the vehicle ground contact pressure 7 kN/m2. As the air-cushion support system can adjust automatically on the terrain, so the vehicle can move over the terrain without any risks. The springdamper system is used with the vehicle body to control the aircushion support system on any undulating terrain by making the system sinusoidal form. Experiments have been carried out to investigate the relationships among tractive efficiency, slippage, traction coefficient, load distribution ratio, tractive effort, motion resistance and power consumption in given terrain conditions. Experiment and simulation results show that air-cushion system improves the vehicle performance by keeping traction coefficient of 71% and tractive efficiency of 62% and the developed model can meet the demand of transport efficiency with the optimal power consumption.

Finite element analysis for the evaluation of protective functions of helmets against ballistic impact

The ballistic impact of a human head model protected by a Personnel Armor System Ground Troops Kevlar® helmet is analysed using the finite element method. The emphasis is to examine the effect of the interior cushioning system as a shock absorber in mitigating ballistic impact to the head. The simulations of the frontal and side impacts of the full metal jacket (FMJ) and fragment-simulating projectile (FSP) were carried out using LS-DYNA. It was found that the Kevlar® helmet with its interior nylon and leather strap was able to defeat both the FMJ and FSP without the projectiles penetrating the helmet. However, the head injuries caused by the FMJ impact can be fatal due to the high stiffness of the interior strap. The bulge section at the side of the Kevlar® helmet had more room for deformation that resulted in less serious head injuries.

Poster 360: The Effect of Newly Designed Dynamic Cushion System With Spring Elements on Buttocks Pressure Distribution in Patients With Spinal Cord Injury

Poster 360: The Effect of Newly Designed Dynamic Cushion System With Spring Elements on Buttocks Pressure Distribution in Patients With Spinal Cord Injury