CAD/CAE OF THE WORKING CHARACTERISTICS OF A NEW TYPE OF FLUID COUPLING SHOCK ABSORBER

For purpose of simulation of the working characteristics of a new type offluid coupling shock absorber for vibration protection of sensitive equipment, a physical model ispresented by analyzing the internal fluid dynamic phenomenon with respect to the coupling shockabsorber and implemented in MATLAB software package. Using the model it is possible to evaluate theimportance of different factors for design of the shock absorber. In the meantime, the key-modelmachine is designed for coupling dynamic test. Comparisons with experimental results confirm thevalidity of the model. So the CAD/CAE software has been developed in MATLAB for design andexperimental test of the new coupling shock absorber.

Fluid structure interaction for circulation valve of hydraulic shock absorber

Based on the working principle and the damping characteristic of hydraulic shock absorber, a fluid structure interaction method was presented, which was used to analyze the microcosmic and high-frequency processing mechanism of fluid structure interaction between circulation valve and liquid of hydraulic shock absorber. The fluid mesh distortion was controlled by the CEL language, and the fluid struc^tre interaction mathematical model was established. The finite element model was established by ANSYS CFX software and was analyzed by dynamic mesh technique. The local sensitive computational area was meshed by prismatic grid, which could reduce the negative volume problem during the simulation. The circulation valve and liquid of hydraulic shock absorber were simulated and analyzed under the condition of sinusoidal inlet velocity loads. Flow characteristic and dynamics characteristic were obtained. The pressure distribution and the displacement of circulation value were obtained, and the acceleration curve of circulation valve was simulated and analyzed. The conformity of the final simulation results with the experimental datum indicates that this method is accurate and reliable to analyze the dynamics characteristic between circulation valve and liquid of hydraulic shock absorber, which can provide a theoretical foundation for optimizing hydraulic shock absorber in the future.

DESIGN METHOD OF MAGNETORHEOLOGICAL FLUID SHOCK ABSORBER FOR CAR SUSPENSION

The Bingham constitutive model, which is previously used in depiction of magnetorheological （MR） fluids rheological behaviors for design devices, exhibits discontinuous characteristics in representation of pre-yield behaviors and post-yield behaviors. A Biviscous constitutive model is presented to depict rheological behaviors of MR fluids and design automotive shock absorber. Quasi-static flow equations of MR fluids in annular channels are set theoretically up based on Navier-Stokes equations and several rational simplifications are made. And both flow boundary conditions and flow compatibilities conditions are established. Meantime, analytical velocity profiles of MR fluids though annular channels are obtained via solution of the quasi-static flow equations using Biviscous constitutive model. The prediction methodology of damping force offered by MR fluid shock absorber is formulated and damping performances are predicated in order to determine design parameters. MR fluid shock absorber for Mazda 323 car suspension is designed and fabricated in Chongqing University, China. Measurements from sinusoidal displacement cycle by Shanchuan Shock Absorber Ltd. of China North Industry Corporation reveal that the analytical methodology and design theory are reasonable.

Dynamical Stability of Cantilevered Pipe Conveying Fluid with Inerter-Based Dynamic Vibration Absorber

Cantilevered pipe conveying fluid may become unstable and flutter instability would occur when the velocity of the fluid flow in the pipe exceeds a critical value.In the present study,the theoretical model of a cantilevered fluid-conveying pipe attached by an inerter-based dynamic vibration absorber(IDVA)is proposed and the stability of this dynamical system is explored.Based on linear governing equations of the pipe and the IDVA,the effects of damping coefficient,weight,inerter,location and spring stiffness of the IDVAon the critical flow velocities of the pipe system is examined.It is shown that the stability of the pipe may be significantly affected by the IDVA.In many cases,the stability of the cantilevered pipe can be enhanced by designing the parameter values of the IDVA.By solving nonlinear governing equations of the dynamical system,the nonlinear oscillations of the pipe with IDVA for sufficiently high flow velocity beyond the critical value are determined,showing that the oscillation amplitudes of the pipe can also be suppressed to some extent with a suitable design of the IDVA.

Unsteady natural convection Couette flow of heat generating/absorbing fluid between vertical parallel plates filled with porous material

The extended Brinkman Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertical channel （formed by two infinite vertical and parallel plates） filled with the fluid-saturated porous medium. The flow is triggered by the asymmetric heating and the accelerated motion of one of the bounding plates. The governing equations are simplified by the reasonable dimensionless parameters and solved analytically by the Laplace transform techniques to obtain the closed form solutions of the velocity and temperature profiles. Then, the skin friction and the rate of heat transfer are consequently derived. It is noticed that, at different sections within the vertical channel, the fluid flow and the temperature profiles increase with time, which are both higher near the moving plate. In particular, increasing the gap between the plates increases the velocity and the temperature of the fluid, however, reduces the skin friction and the rate of heat transfer.

Absorbing Boundary Conditions for Simulating Water Waves Near Solid Bodies

The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.

Theoretical Study and Structural Design of ERF Shock Absorbers

Electrorheologica (ER) technique is a developing technology. In a wide range of engineering applications of ER fluid, shock absorbers employing ER fluids, whose damping force can be controlled continuously and promptly through electric signals, is one of the most prospective applications of ER fluid. In this paper, the theoretical midel and method to predict the damping force of ERF shock absorbers are established.

Electrorheological Fluid and Its Application in Vibration Control

This paper deals with the application of electrorheological fluid (ERF) in shock absorbers. Such shock absorbers (ERF shock absorbers) whose damping force is controlled Continuously and promptly through electric singnals, can be used in many kinds of mechanical equipment for vibration control. Typical structures of ERF shock absorbers are described and requirements for the ERF employed in shock absorbers are discussed. A new kind of shock absorber and its control system are presented and test results of the ERF shock absorber are given.

Application of sustainable basil seed as an eco-friendly multifunctional additive for water-based drilling fluids

Basil seed,containing anionic heteropolysaccharides in its outer pericarp,swells as gelatinous hydrocolloid when soaked in water.In this study,basil seed powder(BSP)was used as a multifunctional additive for water-based drilling fluids.The chemical composition,water absorbency,rheological properties of aqueous suspension of BSP were tested.The effect of BSP on the rheological and filtration of bentonitebased drilling fluid before and after thermal aging was investigated.The inhibition characteristics were evaluated by linear swelling,shale cuttings dispersion and shale immersion test.Lubricity improvement by BSP was measured with extreme pressure lubricity test.The results revealed that incorporation of BSP into bentonite suspension improved rheological and filtration properties effectively after thermal aging of 120℃.BSP exhibited superior inhibitive capacity to xanthan and synergistic effect with KCl.BSP could reduce friction by forming hydration layer.The nanoscale three-dimensional network structures enable BSP to maintain high water retention and absorb strongly on bentonite and metal surface,contributing to enhanced rheology,filtration,inhibition and lubrication properties.The versatile characteristic of BSP,as well as biodegradation makes it a promising additive using in high performance water-based drilling fluid and a potential alternative to conventional synthetic polymers.

A REMARK ON THE ATTRACTORS OF NON-NEWTONIAN FLUIDS

This paper corrects some mistakes in the proof of absorbing sets theorem of at-tractors of non-Newtonian fluids, and establishes again the existence of bounded absorbing sets.

正弦波纹管填充乳化液式吸能构件吸能特性研究

预折纹式吸能构件是目前冲击地压矿井中唯一使用的吸能结构,具有优异的吸能特性,但在屈曲变形过程中存在载荷波动较大、由于摩擦的作用产生火花等问题。针对上述情况,设计了一种正弦波纹管(变径圆管)填充乳化液构成固液耦合体吸能构件(组合构件),研究了波纹管壁厚、母线振幅与出液口直径三个因素对吸能构件吸能特性的影响。建立平均载荷、载荷波动系数与比吸能的预测模型,利用Abaqus有限元软件的光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)粒子算法对模型进行流固耦合分析,通过响应面法对吸能构件的结构参数进行寻优并得到优化结果。研究结果表明,当波纹管壁厚3.959 mm,母线振幅3.721 mm,出液口直径22.161 mm时的吸能构件吸能特性最佳,平均载荷为438.684 kN,载荷波动系数为1.178,比吸能12.123 kJ/kg。通过对比验证,结果具有较高的可信度,为防冲支护装备的吸能环节提供了一种优越的吸能构件。

新型减振器活塞的设计及其阻尼特性分析

减振器是悬挂系统的关键部件,而活塞又作为减振器的重要零件,直接影响着汽车减振性能的好坏。针对中兴新能源汽车减振器的活塞进行创新设计;分析了传统液压减振器的工作原理,运用SolidWorks进行了新型活塞的三维建模,建立了减振器双向流固耦合分析模型,导入ANSYS完成了减振器阻尼特性分析,并进行了试验验证。数据结果表明,相比于传统减振器活塞,新型减振器活塞的减振性能更优同时还减小了阀片的挠度变形,从而提高阀片的寿命;最后通过示功机完成试验,证明了减振器的双向流固耦合数值仿真具有一定的可靠性,新型减振器活塞的结构更优。

可吸收止血绒S-100在骨折内固定手术患者中的应用效果

目的:分析可吸收止血绒S-100在骨折内固定手术患者中的应用效果。方法:回顾性选取2022年3月—2023年6月河南省胸科医院收治的106例骨折内固定手术患者作为研究对象。根据可吸收止血绒S-100的使用情况将其分为对照组和观察组,各53例。对照组术中采用气囊止血带止血,观察组术中采用可吸收止血绒S-100。比较两组围手术期指标,引流量及引流管拔管时间,术前及术后第3天凝血功能。结果:观察组手术时间及住院时间均短于对照组,术中出血量少于对照组,差异有统计学意义(P<0.05)。观察组术后24 h、48 h引流量少于对照组,引流管拔管时间短于对照组,差异有统计学意义(P<0.05)。术后第3天,两组凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)均降低,纤维蛋白原(FIB)及D-二聚体(D-D)均明显升高,观察组PT及APTT均高于对照组,FIB及D-D均低于对照组,差异有统计学意义(P<0.05)。结论:可吸收止血绒S-100应用在骨折内固定手术中止血效果显著,能减少局部渗出,缩短引流周期,对患者凝血功能影响较小。

磁流变减振技术研究与应用

磁流变减振技术作为一种先进的汽车悬架半主动控制技术,在过去几十年中受到了广泛关注。文章旨在探讨磁流变减振技术在汽车悬架系统中的应用,以提升车辆行驶中的稳定性与舒适性。通过分析磁流变液的工作原理及其在磁场作用下的快速响应能力,设计一款基于磁流变减振技术的汽车减震器。按照汽车减震器性能测试标准对进行实验室测试和汽车操稳性能主观评价。结果表明,该磁流变减振器能够有效地快速调节阻尼力,实时适应路况变化,显著减少了车身振动和提高了驾驶舒适性,相对传统减震器有明显的性能优势。验证了磁流变减振技术在提升汽车性能方面的有效性,为进一步的产品开发与批量汽车应用提供了理论支持。

汽车磁流变减振器设计原理与实验测试

根据磁流变体的滨汉塑性模型描述 ,提出了混合工作模式的汽车磁流变减振器的设计原理 ,按照长安微型汽车的技术和磁流变体的性能设计和制作了微型汽车磁流变减振器 ,并根据长安微型汽车前悬架减振器的技术条件对此进行了实验测试。实验结果表明 ,提出的设计原理是可行的 ,对设计特殊阻尼特性的磁流变减振器有一定的指导意义。

汽车磁流变减振器设计准则探讨

提出了微型汽车磁流变减振器的设计准则 ,建立了磁流变减振器的理论分析模型来预估减振器阻尼力的大小。测试结果表明 ,减振器的阻尼力由粘性阻尼力和磁场阻尼力组成 ,随着磁场强度的增加 ,减振器的阻尼力也增大 ,基本上符合理论预估值 ,说明所建立的理论分析模型是可行的。

基于Poiseuille流动的汽车磁流变减振器分析与测试

用牛顿流体模型和滨汉流体模型 ,对基于Poiseuille流动的汽车磁流变减振器进行了分析 ,设计制作了微型汽车磁流变减振器 ,并对此进行了测试 ,测试结果表明 :所提出的分析方法是可行的 。

基于混合模式的汽车磁流变减振器阻尼特性分析与测试

根据牛顿流体模型和滨汉塑性流体模型 ,分别对混合工作模式的汽车磁流变减振器进行了理论分析研究。按照长安微型汽车的技术要求 ,设计和制作了汽车磁流变减振器 ,并对此进行了试验测试。试验结果表明 ,应用所提出的理论分析模型是可行的 ,对设计特殊阻尼特性的磁流变减振器有一定的指导意义。

高稳定磁流变液的制备和性能分析

采用X—ray衍射、扫描电子显微镜及振动样品磁强计等表征手段，研究通过气体渗氮在羰基铁颗粒表面形成的氮化物薄层，分析了羰基铁颗粒氮化后的形貌、抗氧化性能和磁性能。将氮化后的羰基铁粉加入高分散性添加剂，用高速分散的方法制备了高稳定磁流变液，分析了该磁流变液的磁性能、流变性能和抗沉降性能，并研究了该磁流变液在器件应用中的稳定性。结果表明：采用该工艺制备的磁流变液的摩擦系数降低至0．054，3个月沉降〈10％，零场黏度≤1．0Pa·s，最大剪切应力≥60kPa，在20～125℃范围内，阻尼器阻尼力最大衰减率14．3％。氮化提高了磁流变液悬浮相的表面抗磨、耐蚀性能，改善了磁流变液抗沉降团聚稳定性。

汽车磁流变减振器流变力学特性的研究

磁流变液是一种新型的功能材料 ,属于可控流体 它能在强磁场作用下从牛顿流体变为有较高屈服应力的粘塑流体 ,这种变化连续可逆且迅速 ,用其制成的阻尼器具有结构简单、体积小、能耗低和阻尼可连续调节等优点 利用非牛顿粘性流体模型和宾汉流体模型 ,设计基于流动模式的汽车用磁流变减振器 ,利用ANSYS有限元分析软件计算其力学性能并进行试验验证 结果表明磁流变减振器可实现阻尼无级可调 ,将其用于汽车悬架系统 ,可改善行驶的平顺性 。