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J. C. F. Millett - One of the best experts on this subject based on the ideXlab platform.
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Lateral Stress and shear strength behind the shock front in three face centered cubic metals
Journal of Applied Physics, 2009Co-Authors: J. C. F. Millett, G. Whiteman, Neil BourneAbstract:Lateral Stress and shear strength behind the shock front have been measured in three face centered cubic alloys. Results show different behaviors according to microstructure. A hardening response has been shown in pure nickel, while in stainless steel (SS) 304L, hardening has been shown to be minimal. This has been explained in terms of the stacking fault energy effecting the motion and generation of dislocations. In the high stacking fault energy nickel, dislocation motion is comparatively easy, and hence the microstructure consists of dislocation cells, with a pronounced hardening postshock. In SS 304L with its lower stacking fault energy, dislocation motion is more restricted, and hence deformation is dominated by deformation twins. The behavior behind the shock front correlates with the low degree of hardening observed by others during mechanical testing of preshocked samples. The aluminum alloy 6082-T6 also shows a low degree of hardening behind the shock front. This is believed to occur due to the presence of fine intermetallic particles suppressing the formation of dislocation cells but rather forming a random distribution throughout the microstructure.
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STRENGTH OF THE ALUMINIUM ALLOY 6082‐T6 UNDER HIGH STRAIN‐RATE CONDITIONS
2008Co-Authors: J. J. Harrigan, J. C. F. Millett, N. K. BourneAbstract:The measurement of shear strength via the use of Lateral Stress gauges has been shown to be a viable technique in a number of materials. An experimental investigation on the intermediate‐rate behaviour and shock response of the aluminium alloy, 6082‐T6, is reported here. Results obtained using the Lateral Stress gauge technique show that the shear strength increases with impact Stress. The Lateral Stress behind the shock front is seen to be relatively flat, unlike many other face‐centred cubic metals and alloys, where a decrease in Lateral Stress indicates an increase in shear strength. This unusal response may be a reflection of the high stacking fault energy of aluminium and its alloys resulting in a reduction of the work hardening (i.e. increases in dislocation and/or twin density). Further plate impact results show that the Hugoniot of 6082‐T6 is in effect identical to that of the more widely known 6061‐T6. Split Hopkinson pressure bar results are used to provide a fuller picture of the rate‐dependant behaviour of 6082‐T6 over a range of loading rates and conditions.
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Longitudinal and Lateral Stress Measurements in Stainless Steel 304L Under 1d Shock Loading
2008Co-Authors: G. Whiteman, J. C. F. Millett, N. K. BourneAbstract:Interest in the behaviour of the common stainless steel grade 304 at high rates of strain is always high due to the materials regular use in industry. Longitudinal and Lateral Stresses during the shock loading of SS‐304L have been measured using manganin Stress gauges. The shear strength has been shown to increase with impact Stress. Comparison with a pure fcc metal (nickel) shows a significant increase in strength. Strengths are similar to those of mild steel, but the rate of increase with impact Stress is much greater in SS‐304L. These results are discussed in terms of structure and degree of alloying.
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on the effect of manganin gauge geometries upon their response to Lateral Stress
Measurement Science and Technology, 2007Co-Authors: Z. Rosenberg, N. K. Bourne, J. C. F. MillettAbstract:This work concerns the calibration of manganin gauges of different geometry used to measure the Lateral component of the Stress field behind a shock. The response of the gauges was calibrated for a series of Stress levels for two differing gauge geometries. Below a Lateral Stress of about 3.5 GPa, T-shaped gauges have a lower change in resistance than their grid-shaped counterparts. However, above this level, T- and grid-geometries have a common response. Analysis indicates that the T gauges are behaving like embedded wire gauges in this Stress regime. Such behaviour must be accounted for, especially in low impedance materials shocked to low Stress levels.
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Lateral Stress Measurements and Shear Strength of an Alumina‐Filled Epoxy
AIP Conference Proceedings, 2006Co-Authors: K. Kos, J. C. F. Millett, N. K. Bourne, D. DeasAbstract:The variation of shear strength with impact Stress in an alumina‐filled epoxy has been measured with Lateral Stress gauges. At lower Stresses, a degree of hardening behind the shock front has been observed, which diminishes as shock Stress increases. It is believed that this is due to a transition from a viscous response dominated by the epoxy matrix, to a more viscoplastic response. The measured shear strength has also been observed to reach a near constant level, as was suggested in a previous paper. We have also used these results to make an estimation of the HEL at ca. 2.0 GPa.
Cyril Mauffrey - One of the best experts on this subject based on the ideXlab platform.
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Mobilization versus displacement on Lateral Stress radiographs for determining operative fixation of minimally displaced Lateral compression type I (LC1) pelvic ring injuries
International Orthopaedics, 2021Co-Authors: Joshua A. Parry, Motasem Salameh, Stephen C. Stacey, August Funk, Austin Heare, Cyril MauffreyAbstract:Purpose Operative fixation of minimally displaced Lateral compression type I (LC1) pelvic ring injuries is considered by some if the patient is unable to mobilize or displacement is seen on Stress radiographs. The purpose of this study was to compare these methods of determining operative fixation. Methods A retrospective study of a prospectively gathered registry of LC1 injuries was performed before and after the adoption of a mobilization protocol. Fixation was considered if the patient was unable to mobilize 15 feet on the second day of admission. Prior to this protocol, all patients with displacement of ≥ 10 mm on Stress radiographs were offered fixation. All patients received Lateral Stress radiographs (LSR), an anteroposterior pelvis radiograph in the Lateral decubitus positions without sedation, to assess stability. Results There were 21 and 18 patients treated under the Stress radiograph and mobilization protocols. Displacement ≥ 10 mm was present in 12 (57%) and six (33%) patients in the LSR and mobilization groups. Under the mobilization protocol, patients with ≥ 10 mm of displacement on LSR all had incomplete sacral fractures and were less likely to mobilize (2 (33%) vs. 11 (92%); 95% confidence interval of the difference (CID) − 86 to − 9%). The mobilization protocol did not identify all cases of occult instability and resulted in an increased time to surgery compared to the LSR protocol (5 vs. 2 days, 95% CID 1 to 5). Conclusion Under the mobilization protocol, unstable LC1 injuries were less likely to mobilize and the time to surgery was increased.
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Mobilization versus displacement on Lateral Stress radiographs for determining operative fixation of minimally displaced Lateral compression type I (LC1) pelvic ring injuries
International orthopaedics, 2021Co-Authors: Joshua A. Parry, Motasem Salameh, Stephen C. Stacey, August Funk, Austin Heare, Cyril MauffreyAbstract:Operative fixation of minimally displaced Lateral compression type I (LC1) pelvic ring injuries is considered by some if the patient is unable to mobilize or displacement is seen on Stress radiographs. The purpose of this study was to compare these methods of determining operative fixation. A retrospective study of a prospectively gathered registry of LC1 injuries was performed before and after the adoption of a mobilization protocol. Fixation was considered if the patient was unable to mobilize 15 feet on the second day of admission. Prior to this protocol, all patients with displacement of ≥ 10 mm on Stress radiographs were offered fixation. All patients received Lateral Stress radiographs (LSR), an anteroposterior pelvis radiograph in the Lateral decubitus positions without sedation, to assess stability. There were 21 and 18 patients treated under the Stress radiograph and mobilization protocols. Displacement ≥ 10 mm was present in 12 (57%) and six (33%) patients in the LSR and mobilization groups. Under the mobilization protocol, patients with ≥ 10 mm of displacement on LSR all had incomplete sacral fractures and were less likely to mobilize (2 (33%) vs. 11 (92%); 95% confidence interval of the difference (CID) - 86 to - 9%). The mobilization protocol did not identify all cases of occult instability and resulted in an increased time to surgery compared to the LSR protocol (5 vs. 2 days, 95% CID 1 to 5). Under the mobilization protocol, unstable LC1 injuries were less likely to mobilize and the time to surgery was increased.
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The Lateral Stress Radiograph Identifies Occult Instability of Lateral Compression Pelvic Ring Injuries Without Sedation.
Journal of orthopaedic trauma, 2020Co-Authors: Joshua A. Parry, Motasem Salameh, Michael Maher, Stephen C. Stacey, Cyril MauffreyAbstract:To determine if pelvic ring displacement on the Lateral Stress radiograph (LSR) correlated with displacement on examination under anesthesia (EUA). Retrospective cohort study. Urban Level I trauma center. Twenty consecutive patients with uniLateral minimally displaced LC1 injuries with complete sacral fractures. An anteroposterior pelvis radiograph taken in the Lateral decubitus position (LSR) was performed on awake patients before EUA in the operating room. Correlation between ≥1 cm of pelvic ring displacement on the LSR and EUA. The LSR demonstrated ≥1 cm of displacement in 11 of the 20 patients (55%). All of these patients had ≥1 cm of displacement on EUA and underwent surgical fixation. The remaining 9 patients with <1 cm of displacement on the LSR also had <1 cm of displacement on EUA and were managed nonoperatively. The LSR reliably identified occult instability in LC1 pelvic ring injuries and demonstrated 100% correlation with EUA. In contrast to EUA, the LSR does not require sedation and normalizes the amount of force applied to determine instability. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
Neil Bourne - One of the best experts on this subject based on the ideXlab platform.
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Lateral Stress and shear strength behind the shock front in three face centered cubic metals
Journal of Applied Physics, 2009Co-Authors: J. C. F. Millett, G. Whiteman, Neil BourneAbstract:Lateral Stress and shear strength behind the shock front have been measured in three face centered cubic alloys. Results show different behaviors according to microstructure. A hardening response has been shown in pure nickel, while in stainless steel (SS) 304L, hardening has been shown to be minimal. This has been explained in terms of the stacking fault energy effecting the motion and generation of dislocations. In the high stacking fault energy nickel, dislocation motion is comparatively easy, and hence the microstructure consists of dislocation cells, with a pronounced hardening postshock. In SS 304L with its lower stacking fault energy, dislocation motion is more restricted, and hence deformation is dominated by deformation twins. The behavior behind the shock front correlates with the low degree of hardening observed by others during mechanical testing of preshocked samples. The aluminum alloy 6082-T6 also shows a low degree of hardening behind the shock front. This is believed to occur due to the presence of fine intermetallic particles suppressing the formation of dislocation cells but rather forming a random distribution throughout the microstructure.
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Longitudinal and Lateral Stress Measurements in Shock Loaded Polyether Ether Ketone
AIP Conference Proceedings, 2004Co-Authors: J. C. F. Millett, George T. Gray, Neil BourneAbstract:The shock response of poyether ether ketone (PEEK) has been investigated using manganin Stress gauges mounted in longitudinal and Lateral orientation to the impact axis. Measurements of the longitudinal Stress with gauges at different positions within the shock assembly have determined the Hugoniot in terms of shock Stress, shock velocity and particle velocity. It has been shown that the shock velocity has a simple linear response to particle velocity, in common with many but not all polymers. Measurements of Lateral Stress show a decrease behind the shock front, implying an increase in shear strength, possibly due to the viscoplastic nature of PEEK. Shear strength was also observed to increase with shock Stress. A break in slope was observed at ca. 1.0 GPa, indicating a divergence between elastic and inelastic behaviour.
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Shock response of tantalum: Lateral Stress and shear strength through the front
Journal of Applied Physics, 2003Co-Authors: George T. Gray, Neil Bourne, Jeremy MillettAbstract:Lateral Stresses generated by shock loading in tantalum have been determined using manganin Stress gauges. These have been used in combination with the measured longitudinal impact Stresses to determine the shear strength behind the shock. Results show that with an increase in impact Stress, the shear strength in tantalum also increases. Analysis shows that during shock loading the Lateral Stress in tantalum increases behind the shock front. Since the longitudinal Stress is nominally constant until arrival of the release, this implies that the shear strength is reducing behind the shock front. The shock-wave response of tantalum is discussed in the context of a previous weak-shock wave-profile analysis of tantalum, and in terms of the defect generation and storage response of pure face-centered- versus body-centered-cubic metals.
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Lateral Stress measurements and shear strength in a shock-loaded γ - TiAl alloy
Journal De Physique Iv, 2000Co-Authors: Jeremy Millett, George T. Gray, Neil BourneAbstract:Manganin Stress gauges have been placed in samples of a γ-titanium aluminide alloy in such orientation that renders them sensitive to the Lateral component of Stress during one-dimensional shock loading. The impact Stresses were in the range 1.8 to 6 GPa. The resultant Stress histories show clear evidence of a transition from elastic to plastic behaviour, which, through the elastic relations correlates with the Hugoniot Elastic Limit of this material. In combination with the longitudinal Stress data, it has been possible to use the Lateral Stresses from this series of experiments to calculate the shear strength during shock loading. The Hugoniot of the γ-titanium aluminide studied is seen to be significantly different than a standard γ-β Ti-alloy such as Ti-6Al-4V. The results show this titanium aluminide alloy displays a significant degree of hardening with increasing shock Stress.
N. K. Bourne - One of the best experts on this subject based on the ideXlab platform.
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STRENGTH OF THE ALUMINIUM ALLOY 6082‐T6 UNDER HIGH STRAIN‐RATE CONDITIONS
2008Co-Authors: J. J. Harrigan, J. C. F. Millett, N. K. BourneAbstract:The measurement of shear strength via the use of Lateral Stress gauges has been shown to be a viable technique in a number of materials. An experimental investigation on the intermediate‐rate behaviour and shock response of the aluminium alloy, 6082‐T6, is reported here. Results obtained using the Lateral Stress gauge technique show that the shear strength increases with impact Stress. The Lateral Stress behind the shock front is seen to be relatively flat, unlike many other face‐centred cubic metals and alloys, where a decrease in Lateral Stress indicates an increase in shear strength. This unusal response may be a reflection of the high stacking fault energy of aluminium and its alloys resulting in a reduction of the work hardening (i.e. increases in dislocation and/or twin density). Further plate impact results show that the Hugoniot of 6082‐T6 is in effect identical to that of the more widely known 6061‐T6. Split Hopkinson pressure bar results are used to provide a fuller picture of the rate‐dependant behaviour of 6082‐T6 over a range of loading rates and conditions.
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Longitudinal and Lateral Stress Measurements in Stainless Steel 304L Under 1d Shock Loading
2008Co-Authors: G. Whiteman, J. C. F. Millett, N. K. BourneAbstract:Interest in the behaviour of the common stainless steel grade 304 at high rates of strain is always high due to the materials regular use in industry. Longitudinal and Lateral Stresses during the shock loading of SS‐304L have been measured using manganin Stress gauges. The shear strength has been shown to increase with impact Stress. Comparison with a pure fcc metal (nickel) shows a significant increase in strength. Strengths are similar to those of mild steel, but the rate of increase with impact Stress is much greater in SS‐304L. These results are discussed in terms of structure and degree of alloying.
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on the effect of manganin gauge geometries upon their response to Lateral Stress
Measurement Science and Technology, 2007Co-Authors: Z. Rosenberg, N. K. Bourne, J. C. F. MillettAbstract:This work concerns the calibration of manganin gauges of different geometry used to measure the Lateral component of the Stress field behind a shock. The response of the gauges was calibrated for a series of Stress levels for two differing gauge geometries. Below a Lateral Stress of about 3.5 GPa, T-shaped gauges have a lower change in resistance than their grid-shaped counterparts. However, above this level, T- and grid-geometries have a common response. Analysis indicates that the T gauges are behaving like embedded wire gauges in this Stress regime. Such behaviour must be accounted for, especially in low impedance materials shocked to low Stress levels.
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Lateral Stress Measurements and Shear Strength of an Alumina‐Filled Epoxy
AIP Conference Proceedings, 2006Co-Authors: K. Kos, J. C. F. Millett, N. K. Bourne, D. DeasAbstract:The variation of shear strength with impact Stress in an alumina‐filled epoxy has been measured with Lateral Stress gauges. At lower Stresses, a degree of hardening behind the shock front has been observed, which diminishes as shock Stress increases. It is believed that this is due to a transition from a viscous response dominated by the epoxy matrix, to a more viscoplastic response. The measured shear strength has also been observed to reach a near constant level, as was suggested in a previous paper. We have also used these results to make an estimation of the HEL at ca. 2.0 GPa.
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Longitudinal and Lateral Stress measurements in shock-loaded gabbro and granite
Journal of Applied Physics, 2000Co-Authors: J. C. F. Millett, K. Tsembelis, N. K. BourneAbstract:Plate impact experiments have been performed on two igneous rocks of different grain size. Shock Stresses have been measured using embedded manganin Stress gauges, up to ∼12 GPa. In the coarser grained material data was obtained by impacting rock flyer plates onto previously characterized targets. Results are compared and contrasted to the existing data for other geological materials. In the finer-grained material Lateral Stress was also measured. In combination with the longitudinal Stresses, these results have been used to obtain the materials shear strength under shock loading conditions. Results suggest that the material is deforming in an inelastic manner.
Shengchun Liu - One of the best experts on this subject based on the ideXlab platform.
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Lateral Stress Sensor Based on an In-Fiber Mach–Zehnder Interferometer and Fourier Analysis
IEEE Photonics Journal, 2016Co-Authors: Xuefeng Chen, Jintao Zhang, Shengchun LiuAbstract:A novel Lateral Stress sensor based on a compact in-fiber Mach–Zehnder interferometer (MZI) and Fourier analysis is proposed and demonstrated. The in-fiber MZI is formed by cascading two offset splicing joints. The interference occurs between the copropagating fundamental core and cladding modes. The influence of offset value on the performance of modal interferometer, including the extinction ratio and insertion loss, has been experimentally investigated. The spatial spectra of the proposed in-fiber interferometers with different interference lengths are analyzed by Fourier transform. An in-fiber interferometer with an interference length of 30 mm has been fabricated for Lateral Stress measurement. The performance of the Lateral Stress sensor is investigated in a spatial frequency domain by Fourier transform of the corresponding transmission wavelength spectra. The responses of intensity peaks to different Lateral Stresses are analyzed in the spatial frequency domain. The sensitivity of the in-fiber MZI-based Lateral Stress sensor is as high as 0.00455/ $\mu\text{m}$ . The proposed Lateral Stress sensor possesses the advantages of simple and compact structure, high sensitivity, ease of manufacture, and low cost, and it will provide a simple and effective method for detecting the slight fiber deformation induced by Lateral Stress.
