Search results for "STRAIN GAUGE"
showing 10 items of 52 documents
In vivo vibrational wave propagation in human tibiae at different ages
1989
Vibrational wave propagation was tested in vivo on the tibial bone of both legs of 56 female volunteers. The impact was produced by a hammer with a force strain gauge and the response was monitored by two accelerometers. The peak amplitude of the accelerations, the velocity of the acceleration wave propagation and damping were analysed for comparison among the different age groups. The results showed significant negative correlations between age and the peak amplitude of acceleration, and the velocity of acceleration wave propagation (p less than 0.01). The damping time of the acceleration wave also had a negative correlation with age. These findings suggested that age differences were rela…
Flexible multibody simulation approach in the analysis of tibial strain during walking.
2007
Strains within the bone tissue play a major role in bone (re)modeling. These small strains can be assessed using experimental strain gage measurements, which are challenging and invasive. Further, the strain measurements are, in practise, limited to certain regions of superficial bones only, such as the anterior surface of the tibia. In this study, tibial strains occurring during walking were estimated using a numerical approach based on flexible multibody dynamics. In the introduced approach, a lower body musculoskeletal model was developed by employing motion capture data obtained from walking at a constant velocity. The motion capture data were used in inverse dynamics simulation to teac…
Passive RFID Strain-Sensor Based on Meander-Line Antennas
2011
The processing of backscattered signals coming from RFID tags is potentially useful to detect the physical state of the tagged object. It is here shown how to design a completely passive UHF RFID sensor for strain monitoring starting from a flexible meander-line dipole whose shape factor and feed section are engineered to achieve the desired sensing resolution and dynamic range. This class of devices is low-cost, promises sub-millimeter resolution and may found interesting applications in the Structural Health Monitoring of damaged structures and vehicles as well as during extreme and adverse events.
Data Compression Approach for Long-Term Monitoring of Pavement Structures
2019
Pavement structures are designed to withstand continuous damage during their design life. Damage starts as soon as the pavement is open to traffic and increases with time. If maintenance activities are not considered in the initial design or considered but not applied during the service life, damage will grow to a point where rehabilitation may be the only and most expensive option left. In order to monitor the evolution of damage and its severity in pavement structures, a novel data compression approach based on cumulative measurements from a piezoelectric sensor is presented in this paper. Specifically, the piezoelectric sensor uses a thin film of polyvinylidene fluoride to sense the ener…
A Fiber Optic Strain Gage Sensor for Measuring Preload in Thick Composite Bolted Joints
2019
Mechanical fastening is a popular choice in joining composites because of the ability to transfer high loads and the ease of assembly and disassembly. In this study, the failure behavior of composite–aluminum single lap bolted joint is investigated. In particular, the effects of varying the preload on the bolt are examined. In order to accurately measure the preload, a specialized sensor that uses a fiber Bragg grating sensor embedded in the bolt is proposed and created. This sensor is realized for the current tests but can be expanded to other applications. An experimental study of bolted single-lap joints varying the tightening torque value has been carried out and, in order to validate t…
Wireless strain gauge network — Best-hall measurement case
2014
Wireless sensor networks can be used to perform structural monitoring. Strain gauges, which can be glued on or integrated to the observed material, are the most common nondestructive sensing elements for measuring surface strain. Wireless strain gauge measurement system makes strain measurements more flexible while opening new targets of application in addition to those that traditional wired strain measuring systems can offer. We have implemented a long term strain measurement in a PVC-covered hall using wireless sensor network. In this paper we evaluate the functionality and suitability of the developed wireless system for this kind of monitoring. The paper discusses the experiences gaine…
Monitoring road pavement performance through a novel data processing approach, accelerated pavement test results
2020
This research presents a novel performance-based interpretation method for continuous monitoring of pavement condition through the use of piezoelectric sensors. The objective of this study is to validate the compressed cumulative loading event approach, implemented in a previously developed piezoelectric sensor, for detecting subsurface fatigue cracking through full-scale accelerated pavement testing. A piezo-electric film of polyvinylidene fluoride is used to harvest the microstrain energy induced by the traffic loading at the surface. Epoxy is used to protect the sensor following a H-shape packaging. Piezoelectric sensors were exposed to approximately 1.0 million load repetitions between …
Determination of Nonuniform Residual Stresses Using the Ring-Core Method
1996
This paper considers residual stress analysis using the ring-core method. In particular, the so-called integral equation method is applied to evaluate nonuniform residual stress fields. The proposed method overcomes typical drawbacks of the incremental strain method which lead to incorrect results for strongly varying stress fields. The experimental results obtained with a specimen subjected to a bending load confirm the theoretical predictions.
A full body musculoskeletal model based on flexible multibody simulation approach utilised in bone strain analysis during human locomotion
2011
Load-induced strains applied to bone can stimulate its development and adaptation. In order to quantify the incident strains within the skeleton, in vivo implementation of strain gauges on the surfaces of bone is typically used. However, in vivo strain measurements require invasive methodology that is challenging and limited to certain regions of superficial bones only such as the anterior surface of the tibia. Based on our previous study [Al Nazer et al. (2008) J Biomech. 41:1036-1043], an alternative numerical approach to analyse in vivo strains based on the flexible multibody simulation approach was proposed. The purpose of this study was to extend the idea of using the flexible multibod…
Simple equipment to measure biomechanical quantities of muscles and organs which includes a polarity-programmable peak detector
1982
Biomechanical measurements of muscles and organs require appropriate measuring equipment. As far as the static properties are concerned, the excursion of the bender bar of stress should be without force. The bender bar of force, however, ideally should not elongate under load. Because natural frequency is the most important boundary condition, the bender bar should be developed with this in mind. The developed bars imposed an insignificant preload to the muscle or to the organ. The small changes in resistance occurring in the resistance strain gauges affixed to the bars require the use of a highly stable amplifier. A new amplifier was accordingly developed based on the principle of an instr…