Design Of Load Cell Research Articles

Full-Scale Reynolds Number Testing of Rotor Hub Drag and Wake Turbulence

A 1:4.25-scale model of a generic helicopter rotor hub was tested at Reynolds numbers ranging from 1. 75× 106 to 7×106 at advance ratio of 0.2 in The Pennsylvania State University Applied Research Laboratory Garfield Thomas 48-inch diameter water tunnel. Measurements including drag and wake characteristics were performed up to full-scale Reynolds number with respect to an industry-representative helicopter rotor hub. In particular, the variation of drag and flow field with Reynolds number was characterized. Load measurements were conducted using an improved load cell design, with greater accuracy than in previous experiments. Wake velocity was measured using laser Doppler velocimetry at two downstream planes, yielding velocity statistics to the second order. Improved load measurement accuracy and wake velocity spatial resolution, at full-scale Reynolds number, provide a unique dataset for computational fluid dynamics validation as part of the Penn State Rotor Hub Flow Prediction Workshops and physical insight into rotor hub flows.

Both radial and axial load distribution measurement on a V-band clamp by a new load cell design

This paper presents a method for determining the axial and radial load distribution of the moment generated in a V-band clamp and is validated experimentally using finite element analysis (FEA). The method comprises a slotted flange, which is distinguished by having three different profiles for different levels of load symmetrically divided among eight sectors. Each sector is characterised and calibrated. The load cell is analysed using finite element Abaqus software to predict and corroborate the system. In the experimental test, the axial and radial loads are measured using strain gauges for each sector and the total axial load is validated by three button sensors. Tests on the V-band clamp were successfully carried out and indicated a non-uniform distribution of axial and radial loads, with three highlights relating to existing papers: improved results for axial loads, new results for radial loads and an analysis of the moment and its direction, which is consistent with finite element studies.

The Research of Low-profile Load Cell Design Sensitivity

This low profile load cells are referred to the current injection molding machine manufacturers commonly used specifications. This study is about the low-profile load cell design by the finite element analysis and experimental strain measurement verification. In the study, two low-profile load cell were designed and analyzed. The A-type cross-section of the sensor is a generally designed cross-section and has sufficient reliability for commercial use. The B-type curve cross-section load cell from the previous study found that can carry a more significant load. In the study, compare the finite element analysis results with the actual strain measurements to verify the correctness of the analysis. In the experimental verification, the two type sections loadcells were calibrated. The load cells were loading from 0kN to 60kN to measure strain values. The strain values were recorded in experiment processes. When the two types of load cell under loading, the loading force, and strain values regression linearity was 99.99 %. The measured values of the A-type and B-type load cells at 60 kN were 298 με and 170 με, and the results matched finite element analysis strain values. It was shown that the setup of boundary conditions and loading method in finite element analysis were acceptable.

STRUCTURAL SIZING AND SHAPE OPTIMISATION OF A LOAD CELL

This paper presents a structural application of a sizing and shape based on a reliability-related multi-factor optimisation. The application to a load cell design confirmed that this method is highly effective and efficient in terms of sizing and shape optimisation. A simple model of the S-type load cell is modelled in finite element analysis software and the systematic optimisation method is applied. Structural responses and geometrical sensitivities are analysed by a FE method, and reliability performance is calculated by a reliability loading-case index (RLI). The evaluation indices of performances and loading cases are formulated, and an overall performance index is presented to quantitatively evaluate a design.

Multi-Axis Load Cell Designs Employing Multiple Shear Beams

Binocular and parallel plate structure load cells are very successful designs for strain based measurements of shear loads. In this paper we use finite element methods (FEM) to investigate the suitability of these two load cell designs for use in a force plate and compare the sensitivity of these two force plates to that of the Heglund’s force plate. Each force plate is also sensitive to two moments with axis in the same plane as the force plate. If the force plate is to be used as a two component force-moment sensor, we determine which moment axis is best to use. Finally, a novel six-axis load cell is modelled by assembling three force plates together with rotational symmetry. The sensitivity of the six-axis load cell is calculated using FEM. Analysis of the six axis load cell predicts good measurement sensitivity and isotropy while maintaining low interference between measurement axes. Further benefits of the load cell design are discussed.

A novel optical load cell used in icing monitoring on overhead transmission lines

A novel optical load cell based on Fiber Bragg Grating sensing technique was proposed for icing monitoring on high-voltage overhead transmission lines. Compared to the conventional strain gauge load cell, the developed optical load cell has several unique advantages such as unnecessary power supply on site, excellent ability for avoiding electromagnetic interference, and long lifespan. In the load cell design, coupled dual-beam (‘S’ beam) structure was adopted to achieve an accurate measurement, and the part of FBG bonding was carefully chosen to withstand equal and opposite strain, which solved the problem of cross-sensitivity between strain and temperature of FBG sensing. A mixed WDM/TDM (Wave-Division Multiplexing/Time-Division Multiplexing) optical fiber network is proposed to construct an icing monitoring system containing hundreds of FBGs. Result from the tension experiment indicates that the load cell is sensitive to tension, and the sensitivity and resolution of the load cell is 0.04903 pm/N and 20.4 N. The temperature effect on the tension measurement, evaluated by putting the load cell in a temperature-controlled cabinet, is less than ± 0.175%. Furthermore, in order to investigate the reliability of the load cell in icing environment, an experiment was carried out in a climatic chamber, and the results prove that the load cell can work properly in harsh environment.

A Biaxial Load Cell Design for Simultaneous Measurement of Horizontal and Vertical Spring Forces in Sinuous Spring-Supported Seating

Abstract Sinuous springs are the most commonly used method of seat support in upholstered furniture. The dynamics of load transference by these springs to the furniture frame members has not been thoroughly studied. Rational strength design of sinuous-type upholstered furniture frames, especially their seating support systems, requires information concerning the magnitudes and directions of spring loads on spring supporting rails. These values are important for frame designers to be able to adjust member sizes and materials and select appropriate fasteners. Presently, furniture design largely depends on trial and error. A load cell was conceived, designed, and verified which can determine horizontal and vertical components of a spring load. Preliminary results showed that the average initial spring tension on each load cell, with no external loading applied to the springs, was 46 lb. (205 N) horizontal. For some situations, the horizontal load components actually decrease when a person comes to rest on the seat. Vertical and horizontal loading is greatest on the center three springs of the seat which used five, equally spaced springs in this paper.

Real-time in vivo loading in the lumbar spine: part 1. Interbody implant: load cell design and preliminary results.

Instrumented interbody implants were placed into the disc space of a motion segment in two baboons. During the animal's activities, implants directly measured in vivo loads in the lumbar spine by telemetry transmitter. Develop and test an interbody implant-load cell and use the implant to measure directly loads imposed on the lumbar spine of the baboon, a semiupright animal. In vivo forces in the lumbar spine have been estimated using body weight calculations, moment arm models, dynamic chain models, electromyogram measurements, and intervertebral disc pressure measurements. An analytical model was used to determine the force-strain relation in a customized interbody implant. After validation by finite element modeling, strain gauges were mounted onto the implant and connected to a telemetry transmitter. Implants were placed surgically into the L4-L5 disc space of skeletally mature baboons and the transmitter in the flank. After surgery, load data were collected from the animals during activities. Radiographs were taken monthly to assess fusion. The implant-load cell is sufficiently sensitive to monitor dynamic changes in strain and load. During extreme activity, highest measurable strain values were indicative of loads in excess of 2.8 times body weight. The study technique and technology are efficacious for measuring real-time in vivo loads in the spine. Measuring load on an intradiscal implant over the course of healing provides key information about the mechanics of this process. Loads may be used to indicate performance demands on the intervertebral disc and interbody implants for subsequent implant design.

Load cell for dynamic measurement of cutting forces generated during ultrasonic drilling and milling of hard materials

In this work, a novel design of load cell for the measurement of the dynamic forces generated during ultrasonic drilling and milling of hard materials is presented. The transducer, which allows for simultaneous sensing of three components of force, has been designed to minimize the influence of cross-coupling between the components acting in the three perpendicular directions and to measure low levels of force (typically a few tens of Newtons in magnitude) while retaining high mechanical stiffness. This is achieved by utilizing a membrane element for vertical measurement coupled with a multi-beam arrangement for the horizontal axes. The results from static and dynamic analyses of the proposed design conducted using analytical expressions for the membrane and finite element methods for the beam structures are presented. The paper also describes the associated instrumentation set-up, calibration and some example experimental results.

Elastic design of fine mechanism in instruments

Presented is an introduction to an alternative for the kinematic design approach in fine instrument mechanism that was previously given by Furse (1981). It describes purposeful use of elasticity in finite mechanism support design. Explained is the philosophy of flexure supports, the design parameters that are involved and how elasticity can be used to provide controlled linear and angular motion. The content will be of use to designers of mechanical instrument components and is especially relevant to the monolithic moulded plastic and silicon devices. Although the material presented has relevance, elastic load cell design is not covered.

The Fluidic Load Cell

A possible fluidic load cell design consists of three parts: a structural member that deforms linearly with load, a fluidic strain gage having fluidic resistance that changes with deformation, and a three-stage laminar proportional amplifier-gain block that amplifies the change in strain gage through-flow to useful levels. This Technical Brief presents design relations for the first two parts of such a system. Two compressive load cells were built, incorporating different fabrication techniques and deformation-sensing methods. The loading range of these cells is about 0 to 20 kN (0 to 2 tons) with a dynamic range greater than 100 and a typical full-scale output pressure of 30 pascals (4 × 10−3 psi). Possible applications for fluidic load cells include force measurements in highly incendiary or radiative environments and/or when other fluid control circuitry is used.