Suspension Unit Research Articles

Mechanical characteristics of line post type polymer insulation arm for 154 kV

This paper describes the mechanical characteristics of a 154 kV line post type polymer insulation arm that functions both as the steel arm and as the porcelain insulator of the currently used steel transmission towers. The 154 kV line post-type polymer insulation arm consists of polymer composite insulators, called units, that include two horizontal units with an open angle, to respond to a longitudinal load of 40 kN, and a suspension unit to respond to a vertical load. Its installation length is about 2.3 m. Samples of the insulation arm were installed at different places on an electric wire to form a truss structure and a frame structure, in order to examine their mechanical characteristics. For the truss structure, neither remarkable bending stress nor torsional stress was observed in the FRP core. The mechanical force design of the insulation arm can be evaluated in reference to the axial force of the FRP core only. The buckling coefficient, for evaluating the axial force of the insulation arm with the truss structure, was experimentally identified. Moreover, we were able to show that a static load test, for evaluating the mechanical force performance of the insulation arm against a longitudinal load, is more severe than an impact load test at the same longitudinal load. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 23–30, 1999

Active Control for Single Wheel Suspension of Off-Road Track Vehicle

The main objective of ground vehicles suspension system is to isolate a vehicle body (sprung mass) from road irregularities in order to maximize the passenger ride comfort and produce continuous road-wheel contact in order to provide vehicle holding quality. An appropriate active suspension design must resolve the inherent tradeoffs between ride comfort, road holding quality and suspension travel. In this study a robust controller for the active suspension of an off-road, high-mobility tracked vehicle is designed using Quantitative Feedback Theory (QFT). A simulation model of a single suspension unit of the armored personnel carrier vehicle M-113 was used to get a proper active suspension design. Two measured states of the 3 degrees-of-freedom mathematical model were used as feedback signals in a cascaded SISO control system. The nonlinear dynamics of the tracked vehicle suspension unit was represented as a set of linear time invariant (LTI) transfer functions which were identified with the Fourier integral method. Computer simulations of the vehicle with passive and active suspension systems over different terrain profiles are provided. Significant reduction of the vertical accelerations induced to the sprung mass (i.e. ride comfort improvement) was achieved while keeping the road-arm between suspension travel limits (i.e. handling quality). Hence a potential important improvement in cross-country mobility for a wide range of ride conditions could possibly be achieved by application of linear robust control for active suspension design for off-road tracked vehicles.

Development and Simulation of a Novel Roll Control System for the Interconnected Hydragas® Suspension

SUMMARY The design of passive suspension systems using conventional springs and dampers is limited by the need to compromise between vehicle ride and handling functions. The Interconnected Hydragas Suspension fitted to the current Rover 100 series partially allays this compromise by reducing the vehicle pitch stiffness witfiout affecting the bounce and roll stiffnesses. However, the vehicle body is still subject to roll during cornering manoeuvres. This paper outlines the development and simulation of a sealed low bandwidth active roll control suspension based on the existing Interconnected Hydragas System. Following a brief explanation of the Hydragas suspension operating principle die paper outlines the design of a fluid displacer or ‘shuttle’. This shuttle enables control over body roll during manoeuvres by displacing fluid from one side of the car to the other. Care is taken to ensure low power consumption whilst the sealed nature of the fluid based suspension units guarantee reliable operation without leakage. Using computer simulation, the system performance is predicted and compared with experimental measurements. It is shown that roll during manoeuvres can be reduced or eliminated using a minimum of hydraulic components with only moderate power consumption and cost.

154kV用耐張形高分子絶縁アームの機械的特性

This paper describes the mechanical characteristics of a 154 kV line post type polymer insulation arm which has both the functions of a steel arm and a porcelain insulator of a presently used transmission steel tower. The 154 kV line post type polymer insulation arm consists of polymer composite insulators called units which include two horizontal units with an open angle for responding to a longitudinal load of 40 kN and a suspension unit for responding to a vertical load. Its installation length is about 2.3m. Samples of the insulation arm were installed at different places of an electric wire, to form a truss structure and a lahmen structure, for examining their mechanical characteristics. For the truss structure, it was clarified that neither remarkable bending stress nor torsional stress is generated in the FRP core, and that the mechanical force design of the insulation arm can be evaluated in reference to the axial force of the FRP core only. Furthermore, the buckling coefficient for evaluating the axial force of the insulation arm with the truss structure was experimentally identified. Moreover, it was clarified that a static load test for evaluating the mechanical force performance of the insulation arm against a longitudinal load is more severe than an impact load test at the same longitudinal load.

Suboptimal Control Design of Active and Passive Suspensions Based on a Full Car Model

SUMMARY An optimal control design method is introduced and then applied to the optimum design of active and passive suspension systems. A basic three-dimensional 7-DOF car riding model subjected to four correlated random road inputs is considered. The design method is basically developed to allow arbitrary choice of sensors for various car state variables to be used for feedback control of each suspension unit. Previous studies show that full-state control laws and even some limited-state control laws often include feedback gains which are almost zero. Some other gains, although not zero, don't play an important role in improving the system performance measures. With the method proposed in this work, every suspension unit can have its own feedback measurements and the criterion function can be related to all state and control variables. Thus a large number of active and semi-active suspension systems with full- or limited-state control laws based on different measurement combination can be suggested, stud...

Vehicle-Bridge Interaction Analysis by Dynamic Condensation Method

This paper is aimed at the development of a computationally efficient procedure for simulating the dynamic response of general vehicle-bridge systems. With the finite-element method, a vehicle is modeled as lumped masses supported by springs and dashpots, and a bridge with rough pavement by beam elements. An interaction element is defined to consist of a bridge element and the suspension units of the vehicle resting on the element. The composition of an interaction element and the parts of car bodies in contact is regarded as a substructure. By the dynamic condensation method, all the degrees of freedom associated with the car bodies existing within each substructure are eliminated. As the condensation has been performed on the element level, a conventional assembly process can be applied to form the structural equations. Compared with most existing procedures, the present technique appears to be computationally more efficient. It is particularly suitable for the simulation of bridges with a series of veh...

Road Vehicle Benchmark 2 Five-Link Suspension

The problem concerns the kinematic and dynamic behaviours of a five- link suspension unit. The movement of the wheel carrier is constrained by five rods with spherical joints at both ends, so that the overall mechanism has two degrees of freedom: suspension movement of the wheel carrier, and rotation of the wheel. In order to treat the benchmark problem, it was necessary to implement a module for the five-link suspension in the computer program FASIM. For the covering abstract see IRRD 860691.

Quantitative assay for totipotent reconstituting hematopoietic stem cells by a competitive repopulation strategy.

Although hematopoiesis is known to originate in a population of very primitive cells with both lymphopoietic and myelopoietic potential, a procedure for enumerating such cells has to date not been available. We now describe a quantitative assay for long-term repopulating stem cells with the potential for reconstituting all hematopoietic lineages. This assay has two key features. The first is the use of competitive repopulation conditions that ensure not only the detection of a very primitive class of hematopoietic stem cells but also the survival of lethally irradiated mice transplanted with very low numbers of such cells. The second is the use of a limiting-dilution experimental design to allow stem cell quantitation. The assay involves transplanting limiting numbers of male "test" cells into lethally irradiated syngeneic female recipients together with 1-2 x 10(5) syngeneic female marrow cells whose long-term repopulating ability has been compromised by two previous cycles of marrow transplantation. The proportion of assay recipients whose regenerated hematopoietic tissues are determined to contain greater than or equal to 5% cells of test cell origin (male) greater than or equal to 5 weeks later is then used to calculate the frequency of competitive repopulating units (CRU) in the original male test cell suspension (based on Poisson statistics). Investigation of this assay system has shown that all three potential sources of stem cells (test cells, compromised cells, and the host) can under appropriate circumstances contribute to long-term hematopoietic regeneration, thus establishing both the competitive pressure of hematopoietic stem cells in the cotransplanted compromised population and in the host, and the need to use genetic markers to track the specific contribution of the injected test cells. Analysis of the frequency of CRU in test marrow suspensions that varied widely in their CRU content gave similar values when endpoints of either 5 or 10 weeks posttransplantation were used and when either recipient marrow or thymus was used to identify progeny populations. In addition, repopulation of marrow and thymus was found to be associated in most mice injected with limiting numbers of test cells. These findings are consistent with the conclusion that the assay is highly selective for a very primitive, totipotent, reconstituting hematopoietic stem cell and should therefore be particularly useful in future gene therapy-oriented research as well as for more basic studies of hematopoietic stem cell regulation and differentiation.

A new radioimmunoassay for the detection of small amounts of white cells and platelets in red cell concentrates: implications for blood transfusion

In the procedure for quality control of red cell concentrates, made white cell (WBC)-poor by filtration, the particle-counting technique was found to be insufficiently sensitive in detecting the remaining WBCs and platelets. Therefore, direct radioimmunoassays were developed using murine monoclonal antibodies specific for platelets, granulocytes, and T lymphocytes. The sensitivity for platelets was 40 x 10(3) per mL, that for granulocytes was 10 x 10(3) per mL (starting from 0.2 mL of red cell filtrate), and that for T lymphocytes was 0.006 x 10(6) per mL (starting from 5 mL) and 0.0015 x 10(6) per mL (starting from 50 mL). These direct assays were used in experiments on filtration with three types of filters: the Cellselect B-1005, B-1014 and the B-1013 (bedside filter). After filtration of 1 unit of blood cell suspension through the B-1005, the number of remaining platelets was found to vary between less than or equal to 0.04 x 10(6) and greater than 15 x 10(6) per mL (n = 16); after filtration through the B-1013 filter, the remaining platelets were greater than 0.04 x 10(6) per mL. Upon filtration of a second unit of blood cell suspension through the B-1013 filter, the number of remaining platelets varied between less than or equal to 0.04 x 10(6) and 5 x 10(6). In both filter types, the number of remaining granulocytes was always less than 0.01 x 10(6) per mL. A study of T-lymphocyte contamination revealed that, upon filtration of 1 unit of blood through the B-1005, T-lymphocyte numbers were less than or equal to 0.0015 x 10(6) to 0.15 x 10(6) per mL (starting from 5 and 50 mL); upon filtration through the B-1013 filter, the number of remaining T lymphocytes varied between less than or equal to 0.006 x 10(6) and 0.2 x 10(6) per mL (starting from 5 mL). After filtration of a second unit of blood cell suspension through the B-1013 filter, the number of remaining T lymphocytes ranged from less than or equal to 0.006 x 10(6) to 0.1 to 0.5 x 10(6) per mL (starting from 5 mL). The direct radioimmunoassay is an improvement over the present electronic particle-counting techniques with regard to both sensitivity and specificity and may therefore be useful in quality control procedures in blood transfusion as well as in the development of new filters.

Retention of Liquid by Solids in Suspensions and Sediments

Abstract The effects of associated immobile liquid on the settling behavior of particles in solid-liquid suspensions are investigated. The effects are studied with respect to such sedimentation parameters as suspension porosity ∊, final sediment volume fraction us, internal void fraction of the flow unit ui, Steinours parameter A, and McKay's packing factory which corrects for the effective volume and density of the flow units in a sedimenting suspension. It is shown that the degree of liquid association with the settling particles is a function of their physicochemical characteristics. Suspensions containing clays and carbonates, owing to their ionic nature and loose packing behavior, absorb large amounts of liquids and result in larger settled sediments of a compressible nature. On the other hand, systems like glass beads-liquid suspensions absorb little associated liquid and virtually result in noncompressible settled sediments due to their rigid spherical shapes and close packing. The addition of hydrocolloids (such as natural gums) provides ionic stability to suspensions by giving them low cmpressibility and low values of us, ui, A, and p.

Doubling the corrosion resistance of steel springs

A new electrocoat finishing process enables Jonas Woodhead Ltd, one of Europe's leading automotive suspension unit manufacturers, to more than double the corrosion resistance of steel coil springs produced at the company's Sheffield factory.

On the dynamic response at the wheel axle of a pneumatic tire

A method for calculating the steady state displacement response and force transmission at the wheel axle of a pneumatic tire-suspension system due to a steady state force or displacement excitation at the tire to ground contact point is developed. The method requires the frequency responses (or receptances)_of both tire-wheel and suspension units. The frequency response of the tire-wheel unit is obtained by using the modal expansion method. The natural frequencies and mode shapes of the tire-wheel unit are obtained by using a geometrically non-linear, ring type, thin shell finite element of laminate composite. The frequency response of the suspension unit is obtained analytically. These frequency responses are used to calculate the force-input and the displacement-input responses at the wheel axle. This method allows the freedom of designing a vehicle and its tires independently and still achieving optimum dynamic performance.

Elastic System Moving on an Elastically Supported Beam

The problem of a two-dimensional elastic system moving on a beam is considered. The moving elastic system or vehicle is represented by the structural members with distributed stiffness, damping, and inertia properties, and it is supported by the suspension units. Each suspension unit consists of a linear spring, a viscous damper, and an unsprung mass. The beam is supported at discrete points along its length, and/or by an elastic foundation. The deformations of the moving system and the beam are represented by their corresponding eigenfunction series. The resulting governing equations are represented by the coupled, ordinary differential equations with variable coefficients. The equations of motion for an elastic platform moving with constant velocity on a beam are derived and solved by the Hamming’s predictor-corrector method. Numerical examples are presented.

Truck Suspension Models

Laboratory experiments on an International ACCO 1810A truck rear suspension unit are used to assess the validity of mathematical models for the tire and spring. Best results are achieved with tire and spring models that are nonlinear, with separate, fixed loading and unloading curves joined by loading and unloading transitions. The use of a linear tire model with an unloading curve set at 0.9 times the loading curve causes only a small degeneration in accuracy. Alternatively, a linear tire model with a viscous damping coefficient of 0.015 kN/mm/s gives reasonable results. The accuracies achieved with linear models for the suspension spring appear to be unsatisfactory. Details of the transition curves for both tire and spring are unimportant provided that the base length (along the deformation axis) is small.

ORIGIN AND EARLY GROWTH OF CELERY EMBRYOIDS

SUMMARYSuspension cultures of celery embryoids were initiated by transferring portions of differentiating callus to liquid medium. Light microscope studies of the cells and embryogenic aggregates in the suspensions suggested that the embryoids arose from either single cells within the embryogenic aggregates, when the developing embryoid remained attached to the clump until the globular stage, or from free floating small groups of cells. Both types of development showed the celery embryoids to be of single cell origin. When the embryoid suspension was filtered to remove the larger embryoids and the small embryogenic aggregates and free floating embryoids were mixed with agar and plated, the development of the embryoids depended on the initial inoculum density. At low density further embryoid development was delayed while at the high inoculum density the embryoids became green and grew rapidly into torpedo embryoids with cotyledon leaves and roots. At this stage they could be transferred to a simple inorganic medium to develop into plantlets. The effect of inoculum density was thought to be due to a conditioning effect of the environment. It is suggested that the differentiating units in the embryoid suspension could be used in a cell selection procedure.

Design of a Polysil DC Insulator

Under an EPRI sponsored contract, two designs of suspension insulators using Polysil as the dielectric are being developed for use on HVDC overhead transmission lines. These insulators resemble standard porcelain or glass suspension units; however, they are designed to exhibit unique operating characteristics that will make them more desirable for use on HVDC lines. One design is based on the theory that by properly shaping the electric field, a higher percentage of the total contamination will be deposited on the upper surfaces of the insulator. If this can be accomplished, the insulator should have better flashover performance as top surface contamination is more easily removed by wind and rain. A second design is an effort to produce a mechanically fail-safe insulator. This design uses chain-like links that are cast within and separated by the Polysil dielectric. This insulator will prevent a conductor from dropping even if all the dielectric material is destroyed.

Increased somatomedin and cartilage metabolic activity in rabbit fetuses injected with insulin in utero.

The effect of insulin injection in fetal rabbits on plasma somatomedin activity and cartilage metabolism was investigated. One fetus in each of 12 litters was injected with 1 unit of insulin zinc suspension subcutaneously on day 27 of gestation and a control fetus was injected with the same volume of 0.154 mol/l saline. The litter was delivered by caesarean section on day 29 and each fetus identified. Plasma somatomedin activity was determined by fetal rabbit cartilage bioassay. Costal cartilage from individual fetuses was incubated in medium containing [3H]thymidine or [35S]sulphate as indicators of cell replication and matrix synthesis respectively. Individual values for somatomedin activity or cartilage isotope uptake were ranked within a litter. In each case the rank in the litter of the insulin-injected fetus, but not the saline-injected fetus, was significantly higher than the mean rank of the litter. Insulin did not stimulate cartilage metabolism in vitro.

Rubber as an engineering material

The physical and chemical structures of rubber are described. They determine the stress-strain, viscoelastic and fatigue properties and the effect of the environment, which in turn control the use of the material in engineering applications. A short guide to the design of rubber springs is given and the use of rubber in railpads, bridge bearings, and vehicle suspension units is described as a series of examples.

Electron microscopic analysis of human amyloid

This study confirms that amyloid contains at least two distinct morphologic units, the ring and the filament. A method for obtaining both of these units in the same amyloid suspension is described. The two units are observed side by side, and their measurements are given. Both units are considered characteristic of the particulate amyloid, and their ratio is about 90–95 % filaments and 5–10 % rings. A model of the fibril ultrastructure is proposed. The effects of various purification methods on amyloid morphology are discussed.

The Railway Wheelset and Suspension Unit as a Closed-Loop Guidance Control System: A Method for Performance Improvement

Using a simplified mathematical model, the conventional railway wheelset and suspension unit is shown to behave as a closed-loop guidance control system. The centre-line of the track corresponds to the input, and the lateral position of the centroid of the wheelset to the output. Analysis of the system shows that, while it may be made stable at up to high speeds, the performance in the stable region is unsatisfactory in certain respects. This is attributed to the large forces of interaction between the wheels and rails at the points of contact, arising, in the case of the conventional wheelset, from creepage. These forces may be reduced and controlled by interposing a coupling having viscous characteristics between the wheels, in place of the rigid axle. The new arrangement is shown to be much more flexible, and capable of fulfilling a wide range of performance requirements.