Development of a Temperature Calibration Device for Thermoelastic Stress Analysis

Dulieu-Barton, J.M.; Quinn, Simon; Eyre, Chris; Cunningham, Paul

doi:10.4028/www.scientific.net/amm.1-2.197

Cited by 15 publications

(12 citation statements)

References 6 publications

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“…This method of evaluating K from several locations of predicted stress (typically polyaxial) is a reduced version of a more extensive approach recently utilised by Ju and Rowlands [7] for orthotropic composites. Refs [1, 8, 9] describe several other methods of evaluating K , including separate calibration coupons.…”

Section: Resultsmentioning

confidence: 99%

Thermoelastic Determination of Individual Stresses in a Diametrally Loaded Disk

Foust

Rowlands

2011

Strain

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In a cyclically loaded structure which experiences adiabatic and reversible conditions, the measured change in temperature is associated with the change in the stresses. For proportional loading and isotropy, the technique measures information on the sum of the principal stresses. As engineering analyses frequently necessitate knowing the individual components of stress, supplementary experimental methods or information is sometimes required to ‘separate the stresses’. This need is circumvented here in that individual stresses are evaluated throughout a loaded disk without additional measured data by hybridising the TSA information with an Airy stress function and some known boundary conditions. Although demonstrated here to a circular aluminium disk under diametral compression, the approach is applicable to more complicated shapes, under more complex loadings and inverse problems. The technique does not pre‐suppose knowing the details. While TSA information has been displayed previously for a loaded disk, the authors are unaware of the stresses being thermoelastically separated for this case.

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Section: Resultsmentioning

confidence: 99%

Thermoelastic Determination of Individual Stresses in a Diametrally Loaded Disk

Foust

Rowlands

2011

Strain

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“…As mentioned in Chapter 2, thermodynamic analysis of a reversible adiabatic behavior of stressed, elastic element produces Equation 2.3. To maintain the adiabatic conditions, frequency of loading should exceed 3Hz [93,116]. A 5Hz frequency was used in our investigation.…”

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confidence: 99%

A biomechanical investigation of the surface stress of a synthetic femur using infrared thermography validated by strain gauge measurements

Shah¹

2023

Preprint

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As the North American population ages, there will be a massive increase in musculoskeletal impairments because these problems are most common in the elderly. A very common condition is osteoporosis, which can result in fractures. Therefore, the need for improved orthopaedic fracture repair implants is vital. Currently, the two main approaches in studying orthopaedic implants are strain gauge measurements and finite element modelling. This study introduces and validates a relatively new, non-destructive approach in analysing stress patterns in a biomechanics application. Lock-in infrared (IR) thermography calibrated with strain gauges was used to investigate the stress and strain patterns of a synthetic femur under dynamic loading. The femur was instrumented with strain gauges and tested using axial average forces of 1500N, 1800N, and 2100N at an adduction angle of 7 degrees to simulate the single-legged stance phase of walking. Three dimensional surface stress maps were obtained using an IR thermography versus strain gauge data with a Pearson correlation of R² = 0.99 and a slope ranging from 0.99 to 1.08, based on thermoelastic coefficient (Km) ranging from 1.067 x 10⁻⁵/MPa to 1.16 x 10⁻⁵/MPa, for the line of best fit. IR thermography detected bone peak stresses on the superior-posterior side of the femoral neck of 91.2MPa (at 1500 N), 96.0Mpa (at 1800 N), and 103.5MPa (at 2100 N). There was strong correlation between IR measured stresses and force along the anterior (R² = 0.87 to 0.99), posterior (R² = 0.81 to 0.99) and lateral (R² = 0.89 to 0.99) surface. This is the first study to provide an experimentally validated three dimensional stress map of a synthetic femur using IR thermography.

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“…The temperature images were captured after 1000 cycles to ensure reaching adiabatic conditions where the temperature change is stabilized. Also, the loading frequency should exceed 3 Hz to maintain steady state conditions [163]. For the best quality images, the image capturing frequency was synchronized with the loading frequency at 5 Hz.…”

Section: Thermographic Imagingmentioning

confidence: 99%

Biomechanical development and analysis of a new carbon-fiber/flax/epoxy plate for repairing femur fractures

Bagheri¹

2022

Preprint

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Femur fracture at the tip of a total hip replacement (THR), commonly known as Vancouver B1 fracture, is mainly treated using rigid metallic bone plates, which may result in "stress shielding" leading to bone resorption and implant loosening. To minimize "stress shielding", a novel carbon fiber (CF)/Flax/Epoxy composite plate with a “sandwich structure” has been developed and characterized mechanically, biologically and biomechanically compared to a standard clinical metal plate. The CF/Flax/Epoxy composite material showed no cytotoxicity with no negative influence on the expression level of bone formation genes at all incubation time. The results of mechanical tests revealed a considerably high ultimate strength in tension (399.8 MPa), flexion (510.6 MPa) and fatigue loading (200-220 MPa). The composite plate showed higher elastic modulus in bending tests (57.4 GPa) compared to tension tests (41.7 GPa). The dynamic modulus (E*) was found to stay almost constant versus the number of cycles, which can be related to the contribution of both flax/epoxy and CF/epoxy laminae to the stiffness of the composite. The results of biomechanical assessment of the plate showed that the bone beneath the CF/Flax/Epoxy plate was the only area that had a significantly higher average surface stress (fractured = 2.10 ± 0.66 MPa; healed = 1.89±0.39 MPa) compared to bone beneath the metal plate (fractured = 1.shielding” effect. The CF/Flax/Epoxy plated femur had comparable axial stiffness (fractured = 645 ± 67 N/mm; healed = 1731 ± 109 N/mm) to the metal plated femur (fractured = 658 ± 69 N/mm; healed = 1751 ± 39 N/mm) (p=1.00). These results confirm that the new CF/Flax/Epoxy material could be a potential candidate for bone fracture plate applications as it shows good biocompatibility and considerably higher strength in tension, flexion and fatigue than actual clinical load level experienced by femur during daily normal activities. Moreover, it can simultaneously provide similar mechanical stiffness and lower “stress shielding” (i.e. higher bone stress) compared to commercially-used metal bone plates.18 ± 0.93 MPa; healed = 0.71 ± 0.24 MPa) (p<0.05), cause less “stress

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Development of a Temperature Calibration Device for Thermoelastic Stress Analysis

Abstract: A means of calibrating the effect of temperature on the thermoelastic signal obtained from the Deltatherm system is described. A design of a suitable calibration device is covered and sample results presented and discussed.

Cited by 15 publications

References 6 publications

Thermoelastic Determination of Individual Stresses in a Diametrally Loaded Disk

Thermoelastic Determination of Individual Stresses in a Diametrally Loaded Disk

A biomechanical investigation of the surface stress of a synthetic femur using infrared thermography validated by strain gauge measurements

Biomechanical development and analysis of a new carbon-fiber/flax/epoxy plate for repairing femur fractures

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