Height Deformation Research Articles

Structural fuse design of bolted steel frame with low yield point angle steel connection components

In order to realize the urgent requirement for damage control and rapid recovery of structural function after earthquake excitations using more convenient strategies, a bolted steel frame equipped with replaceable dissipative angle steel connection components was proposed. These angle steels with designed free deformation length were made of low yield point steels (LYP) which have superior ductility, dissipation capacity and fatigue performance. The plastic deformation was expected to be circumscribed within the LYP angle steels, which behaved as structural fuses to protect the primary frame members and were easy to be demolished and replaced. To achieve this desired damage control objective, the quantitative influence of the key factors on the seismic performance and the structural fuse effect was evaluated via extensive numerical parametric analyses. The design procedure of the corresponding sizes of LYP connection components to act as structural fuses was further summarized on account of energy dissipation behavior. The analysis results demonstrated that the larger the strength reduction factor (the smaller design resistance capacity coefficient), free deformation length and height of beam section promoted the structural fuse action of the LYP connection components. In terms of comprehensive consideration of structural ductility, load-carrying capacity, structural fuse performance and material efficiency, the design resistance capacity coefficient (the strength reduction factor) was suggested as αd=0.8∼1.0, and the free deformation length ranged from 0.67 to 1.1 times of beam width. The critical value of the design resistance capacity coefficient to achieve desirable structural fuse effect was formulated by integrating above-mentioned key influencing factors. Consequently, the design resistance capacity coefficient was required to be less than this critical value to realize sufficient damage control objective.

A magnetic actuation scheme for nano-kirigami metasurfaces with reconfigurable circular dichroism

Nano-kirigami-based deformable metasurfaces offer unique advantages in the dynamic modulation of optical fields and the realization of reconfigurable micro-/nano-optoelectronic devices. Here, we theoretically propose and numerically demonstrate a magnetically actuated deformation scheme for 2D nano-kirigami structures, which can be accurately and continuously transformed from 2D to 3D. Based on the traditional pinwheel structure, an Fe/Au bilayer anti-pinwheel nanostructure is designed and dynamically transformed by employing magnetic attraction in numerical simulations, in which the ratio between deformation height and lateral period could reach up to 0.563. More importantly, it is found that the anti-pinwheel structure has superior circular dichroism (CD), whose maximum CD response could reach 7 times that of the corresponding pinwheel structure. Further analysis of the scattering power of multipole moments reveals that such a superior CD response is found to be induced by the handedness-dependent excitation of a toroidal dipole moment. Such a straightforward magnetically actuated deformation and novel anti-pinwheel structure provides useful methodologies to explore and realize deformable metamaterials and their dynamic regulation capabilities, as well as applications in chiral spectroscopy, optical reconfiguration, optical sensing, etc.

Plasmonic diastereoisomer arrays with reversed circular dichroism simply controlled by deformation height

Chirality reversal between enantiomers is of great importance in both fundamental science and practical applications in chiroptics, biomedicine, and analytical chemistry. Here, we demonstrate an abrupt sign reversal of circular dichroism (CD) between artificial plasmonic diastereoisomers, which are a kind of stereo twisted metamolecules with different strength of deformations. The sign of the CD response is reversed in the same wavelength region by simply engineering the deformation height of nanostructures. Electromagnetic multipolar analysis shows that the sign of CD is determined by the phase-controlled handedness-dependent excitations of electric quadrupole modes. The numerical simulations are further verified by experiments using a nano-kirigami fabrication method. This work reveals that under certain circumstances, the CD response of the plasmonic diastereoisomers can be very close to that of enantiomers, which is useful for the exploration of profound chiroptics, as well as for the applications in chirality switching, chiral biosensing, and chiral separation.

Posterior short segment fixation including the fractured vertebra in unstable burst fractures of thoracolumbar region in Nepal

The objective of this study was to observe the outcome of short segment fixation of the unstable burst fracture in the thoracolumbar region. The study was conducted on 30 patients (age: 21-50 years) from February 2019 to August 2020 with thoracolumbar burst fracture (T10–L2). In Magerl Type A fractures, all underwent posterior pedicle screw fixation, including the fractured vertebra. The functional evaluation was done by Visual Analogue Score (VAS), Oswestry disability index (ODI), ASIA grade and radiologic parameters (Cobb angle, the kyphotic deformation and vertebral height) were recorded immediately preoperatively and at 3, 6 and 12 months then yearly. The presence of screw pullout, screw breakage, rod breakage and peri-implant loosening were evaluated as implant failure. Most of the fractures resulted from falls (21 cases), and the remaining from the road traffic accidents (9 cases). The fractured level was L1 in 13 patients, T12 in 9 patients, L2 in 6 patients and T11 and T10 in 2 patients. The modified Mcnab criteria were excellent in 18 cases, good in 11 cases and poor in 1. All patients showed improvement in mean kyphotic angle. Their pre-operative, post-operative and final follow-up mean kyphotic angle were 13.5±6.3, 13.4±4.3, 8.5±6 degrees, respectively. The average loss of kyphosis correction was 6.4±5.2° at the final follow-up. The pre- and post-operative kyphotic deformity of the vertebral body were 5.1±3.2, 4.8±2.3 and at final follow-up was 4.5±4.0 (p>0.05). Both posterior and anterior vertebral height improved significantly post-operatively with no significant loss of height at final follow-up. Functional outcomes mean ODI was 17.4% and VAS score was 1.7 at the end of one year. No complications were seen postoperatively and at final follow-up. In conclusion, short-segment pedicle screw fixation, including fractured vertebra was capable of reducing and maintain the reduction of unstable burst fractures of the thoracolumbar region.

Novel Radiographic Measurements for Operatively Treated Haglund's Deformity.

Background: Haglund’s deformity, which is characterized by a bony prominence of the posterosuperior aspect of the calcaneus, causes posterior heel pain. To date, there is no standard radiographic parameter to diagnose symptomatic Haglund’s deformity. Herein, we proposed novel radiographic measurements to distinguish between patients with and without symptomatic Haglund’s deformity. Methods: We retrospectively evaluated ankle radiographs of 43 patients who underwent surgery for symptomatic Haglund’s deformity (Haglund group) and 41 healthy individuals (control group) free of heel complaints. Fowler–Phillip angle (FPA), Heneghan–Pavlov parallel pitch lines (PPL), Haglund’s deformity height, bump height, and bump-calcaneus ratio were measured and compared between the groups. Furthermore, the reliability and cut-off value of each parameter were validated via ICC and ROC curve analysis, respectively. Results: The bump height (p < 0.001) and the bump-calcaneus ratio (p < 0.001) showed significant differences between the control and Haglund groups, unlike FPA, PPL, and Haglund’s deformity height. ROC curve analysis revealed that the AUC of bump-calcaneus ratio was larger than that of bump height. The optimal threshold was 4 mm or higher for bump height and 7.5% or higher for bump-calcaneus ratio. The intra- and inter- observer ICCs were, respectively, 0.965 and 0.898 for bump height and 0.930 and 0.889 for bump-calcaneus ratio. Conclusions: This study proposes two novel radiographic parameters to identify operatively treated Haglund’s deformity, namely bump height and bump-calcaneus ratio. They are easy to measure and intuitive. Both of them are effective diagnostic parameters for Haglund’s deformity. Furthermore, bump-calcaneus ratio is more reliable diagnostic parameter than bump height.

Numerical Investigation of the Influence of Tire Deformation and Vehicle Ride Height on the Aerodynamics of Passenger Cars

Wheels and wheel houses contribute up to 25% of the total aerodynamic drag of passenger cars and interact in a complex way with their surroundings. Rims and tires induce complex flow separation mechanisms in a highly unsteady regime and the proximity to the ground enhances these phenomena. To have a clearer understanding of the flow mechanisms that develop around wheels and inside wheel houses, the effect of tire deformation and vehicle ride height on the aerodynamics of passenger cars has been investigated with unsteady CFD simulations. Tire deformation is modelled with an empirical formulation that provides close-to-real deformed shapes, while vehicle ride height changes are made by applying vertical translations the vehicle body. Slick tire geometries and closed rims have been analysed and their rotation has been modelled with a tangential velocity component applied to their surface. The investigation has been conducted in three steps: different car heights and tire deformation levels have been investigated separately and then combined, classifying the results on the basis of the drag of the vehicle. Results show that even small tire deformation levels can significantly affect the aerodynamic drag, thus deformation should be included in simulations and treated with caution.

Effect of the aging process on the micro-structure &amp; properties of 7075 aluminum alloy using electromagnetic bulging

7075 aluminum alloy is a high-strength aluminum alloy which is widely used in the aircraft industry. However, its poor ability to form at room temperature restricts its applications. Electromagnetic forming (EMF) can significantly improve the forming limit of difficult-to-deform materials. In this paper, solution quenching (SQ), electromagnetic forming, and aging treatment were used to analyze the forming and mechanical properties of the 7075 aluminum alloy. The forming height when using SQ was 127% higher than for T651. For the same deformation height, the discharge energy when using SQ was 39% of that of T651. The effects of aging time on the microstructure and properties of the 7075 aluminum alloy were investigated using Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). As the aging time increases, the dislocation density decreases, the number of precipitated η′ phases decreases, and the number and size of precipitated η phases increases. The optimum aging time is 18 h, which yields comprehensive mechanical properties for the alloy.

Understanding the friction and deformation behavior of micro/nano-hierarchical textures through in-situ SEM observation and mechanics modeling

Micro/nano-hierarchical textures play essential roles in realizing the functionalities of surfaces. Their friction and deformation behavior at the nanoscale, although important, are relatively unknown. In this study, through targeted friction tests inside a scanning electron microscope of individual micro/nano-hierarchical structures (micropillars covered with nanohairs) fabricated by two-photon lithography, we discovered the coupling between micropillar deformation and nanohair height. We also found that the bending of long nanohairs can provide assistive sliding forces, and lateral force can develop even under just normal load before sliding due to the buckling of the longer nanohairs. These findings, supported by finite element modeling of the tests, will shed light on the design of novel micro/nano-hierarchical textures to realize deformation-resistant functional surfaces with controlled friction.

Large ellipsoid parts manufacture using electromagnetic incremental forming with variable blankholder structure

Large ellipsoid parts are prone to wrinkle when forming by using traditional stamping. Aiming to solve the wrinkling problem in large parts, the EMIF method with a variable blank holder is proposed in this paper. The numerical simulation has shown that the sheet material near the blank holder is, as a consequence of stamping, subjected to circumferential compressive stress. When the drawing height was 100 mm, the sheet metal was notably wrinkled. In the electromagnetic forming (EMF) process, the sheet region facing the coil becomes thinner. However, the sheet metal thickness corresponding to the coil edge increases with the increase in forming height. If the EMF forming height is 150 mm, the sheet, which is in contact with the smooth mold, is deformed without a wrinkle. Compared to traditional stamping, the EMF can significantly reduce the sheet metal wrinkling, improving the deformation height of the sheet metal smooth area.

Open Versus Endoscopic Osteotomy of Posterosuperior Calcaneal Tuberosity for Haglund Syndrome: A Retrospective Cohort Study.

Background:Although endoscopic calcaneoplasty and retrocalcaneal debridement have been extensively applied to treat Haglund syndrome, evidence of the value of the endoscopic procedure remains to be fully established.Purpose/Hypothesis:The purpose of this study was to compare the postoperative outcomes and the amount of osteotomy between open and endoscopic surgery for the treatment of Haglund syndrome. It was hypothesized that endoscopic calcaneoplasty would lead to higher patient satisfaction and lower complication rates compared with open surgical techniques.Study Design:Cohort study; Level of evidence, 3.Methods:The following postoperative outcomes were compared between the open surgery group (n = 20) and the endoscopic surgery group (n = 27): visual analog scale for pain, American Orthopaedic Foot & Ankle Society ankle-hindfoot scale, Foot Function Index, Tegner score, Ankle Activity Score, and 36-Item Short Form Health Survey; postoperative complications; and duration of surgery. To determine the extent of resection, the authors compared the calcaneal height ratio, calcaneal resection ratio, calcaneal resection angle, pitch line, and Haglund deformity height between groups. The learning curve for endoscopic calcaneoplasty was also calculated.Results:There were no significant differences between the open and endoscopic groups on any outcome score. Two patients in the open group reported temporary paresthesia around the incisional site, indicating sural nerve injuries; no complication was reported in the endoscopy group. None of the parameters for extent of resection were statistically significant between the groups. The duration of surgery was 44.90 ± 10.52 and 65.39 ± 11.12 minutes in the open and endoscopy groups, respectively (P = .001). Regarding the learning curve for endoscopic calcaneoplasty (6 surgeons; 27 follow-up patients; 9 patients lost to follow-up), the duration of surgery reached a steady point of 55.68 ± 4.19 minutes after the fourth operation.Conclusion:The results of this study indicated that the endoscopy procedure was as effective as the open procedure. The endoscopic procedure required significantly more time than the open procedure, and the duration of the endoscopic procedure was shortened only after the fourth operation, suggesting that it requires high technical skills and familiarity with the anatomic relationships.

Design of cylindrical soft vacuum actuator for soft robots

Soft robots have been significantly studied in recent decades, and among their key components are soft actuators. Vacuum is one of the main drivers of soft actuators. In this study, we propose a novel cylindrical soft vacuum actuator (CSVA) consisting of a top layer, bottom layer, and cylindrical internal chamber. Under a vacuum, the bottom layer was concaved into the internal chamber. A simplified analytical model was established to analyze the relationship between the vacuum pressure and the deformation height of the bottom layer. A validation experiment was conducted to verify the effectiveness of the proposed analytical model. The potential applications of the CSVA in the design of soft robots were also explored. A jellyfish-inspired swimming robot, an octopus-inspired suction cup, and a soft–rigid gripper were designed according to the concave deformation of the bottom layer. Then, the swimming speed of the swimming robot, the adsorption force of the suction cup, and the grasping capability of the soft–rigid gripper were investigated. The experimental results show that the maximum swimming speed of the swimming robot is 55.3 mm s−1 at a flapping frequency of 0.6 Hz. The adsorption forces of the suction cup both in air and underwater are 16.8 N and 17.5 N, respectively. The soft–rigid gripper with a pinching-grasping mode can grasp objects of various shapes and sizes in air and underwater. The experimental results demonstrate the feasibility of the soft vacuum actuator in the design of various soft robots.

Effects of process configuration and sheet thickness on the deformation behaviour in multi-step electromagnetic forming of aluminium alloy sheet

Multi-step electromagnetic forming is a novel sheet metal forming approach which makes use of electromagnetic force acting on sheet metal incrementally to cause local deformation and further accumulate a final shape. The effects of process configurations including incremental interval and discharge voltage as well as sheet thickness on the radius of curvature and deformation height are investigated by conducting experiments on 2524-T3 aluminium alloy sheet. It is found that the deformation curvature of the workpiece increases with decreasing incremental interval initially, then tends to be saturated. In addition, the enhancement of the discharge voltage proves to be an efficient method for increasing the ultimate curvature and deformation height. However, the pit defect induced by the large discharge voltage has a significantly negative influence on the surface integrity of the fabricated part when discharge voltage exceeds a critical value of 7500 V. Furthermore, the deformation height decreases with increasing sheet thickness under the other same process parameters.

A Phase Filtering Method with Scale Recurrent Networks for InSAR

Phase filtering is a key issue in interferometric synthetic aperture radar (InSAR) applications, such as deformation monitoring and topographic mapping. The accuracy of the deformation and terrain height is highly dependent on the quality of phase filtering. Researchers are committed to continuously improving the accuracy and efficiency of phase filtering. Inspired by the successful application of neural networks in SAR image denoising, in this paper we propose a phase filtering method that is based on deep learning to efficiently filter out the noise in the interferometric phase. In this method, the real and imaginary parts of the interferometric phase are filtered while using a scale recurrent network, which includes three single scale subnetworks based on the encoder-decoder architecture. The network can utilize the global structural phase information contained in the different-scaled feature maps, because RNN units are used to connect the three different-scaled subnetworks and transmit current state information among different subnetworks. The encoder part is used for extracting the phase features, and the decoder part restores detailed information from the encoded feature maps and makes the size of the output image the same as that of the input image. Experiments on simulated and real InSAR data prove that the proposed method is superior to three widely-used phase filtering methods by qualitative and quantitative comparisons. In addition, on the same simulated data set, the overall performance of the proposed method is better than another deep learning-based method (DeepInSAR). The runtime of the proposed method is only about 0.043s for an image with a size of 1024×1024 pixels, which has the significant advantage of computational efficiency in practical applications that require real-time processing.

Phase and Texture Evolution of Hot-Deformed Sm(Co,Fe,Cu,Zr)z Magnet

Phase and texture evolution of the hot-deformed Sm(Co,Fe,Cu,Zr)z magnet prepared by spark plasma sintering (SPS) have been investigated. The effects of hot deformation temperature and height reduction on the phase structure and magnetic properties of the magnet were studied. The results show that with 90% height reduction at 900 °C, the hot-deformed magnet with TbCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> structure obtains an obvious c-axis texture. However, with increasing hot deformation temperature, some 1:7H phases decompose into 2:17R, 1:5H, and Zr-rich particle phases in the hot deformation process. The hot-deformed magnet with 85% height reduction possesses a remanence (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ) of 6.9 kG, which is higher than that of the isotopic precursor.

Fault Model of the 1804 Kisakata Earthquake (Akita, Japan)

AbstractThe 10 July 1804 Kisakata earthquake occurred offshore Kisakata (Akita, Japan), and widespread felt shaking was reported from Matsumae (Hokkaido) to Ohmi-Hachiman (Shiga Prefecture). The earthquake caused strong ground motions that extensively damaged areas near the epicenter, such as along the coast of Kisakata, and the resultant tsunami caused extensive damage along the coast from Kisakata to Sakata. Furthermore, Kisakata lagoon was uplifted by dislocation during the earthquake, exposing the lagoon floor. Here, we performed a field survey of the uplift distribution based on microtopographic remnants of the former shoreline of Kisakata lagoon and used historical documents to re-evaluate tsunami trace heights. Using ocean-bottom reflection profiles, we estimated a fault model for the earthquake and resultant tsunami. Our model indicates that an average of 5.6 m of slip on the fault (equivalent to an Mw 7.1 earthquake) is required to explain the observed crustal deformation and tsunami height distributions, and back correction of the modeled slip reproduced well the former shoreline of Kisakata lagoon.

Deformation of a Liquid Near an AFM Tip: Molecular Dynamics Approach.

The interaction between an atomic force microscopy (AFM) probe and a thin film of water deposited over a flat substrate is studied using molecular dynamics (MD). The effects of the film thickness and the probe radius on both the deformation height of the liquid interface and the distance of the jump to contact at which the liquid comes in direct contact with the probe are investigated. The dynamics of the surface deformation and the role of interface fluctuations are studied in detail. The systems considered belong to the thin-film regime described in a semianalytical model previously established by Ledesma-Alonso et al. (Langmuir 2013, 29, 7749-7757). MD simulations predict that for shallow films, both the distance at which the jump to contact occurs and the surface maximal deformation height increase steadily with the layer thickness regardless of the probe radius, which is in agreement with the previously proposed theoretical model. The deformation of the surface was shown to be unstable because of the strong effect of thermal fluctuations. For each of the considered systems, the film thickness was such that interface fluctuations induced the jump to contact. The comparison of the deformation obtained in MD with the profiles predicted by the continuous model points out the complementarity between the two approaches. The results of the molecular approach not only are consistent with those of the continuous model but also provide more information on the description of nanoscale phenomena. In particular, MD results point out the importance of fluctuations when it comes to the description of the particular dynamics of nanosystems involving soft interfaces. This shows the need to improve continuous models by complementing them with a molecular approach for a better accuracy.

Formability and deformation mechanism of Ti-6Al-4V sheet under electropulsing assisted incremental forming

Electropulsing assisted incremental forming as an advanced technology could enhance the formability of hard-to-deform metal. However, the mechanism behind this improvement has not been clearly investigated. In this work, the texture development, fracture characteristic, strain variation and microstructure evolution were analyzed to study the deformation behaviors of Ti-6Al-4V alloy during electropulsing assisted incremental forming. The effect of orthotropic basal texture evolution on the crack propagation behavior presented that the electropulsing decreased the strong texture strength along the transverse direction, delaying the crack propagation along the rolling direction. Moreover, electropulsing caused the (0001) base texture weakening, and the weakening of anisotropy behaviors led to the formability enhancement. The maximum deformation height of 21.7 mm and the forming angle of 66.5° were obtained. The deformation height was increased by 417.9% compared to conventional ambient incremental forming. The strain analysis results showed that the thickness strain difference along the rolling and transverse directions was reduced under the electropulsing. It was consistent with the phenomenon that the crack propagation direction along the rolling direction at room temperature was changed to the rolling and transverse directions under electropulsing. Another important observation on research was that anisotropic microstructure along different directions tended to be uniform due to the occurrence of dynamic recrystallization under electropulsing.

Glass flow behaviors in micro-channels during hot embossing

A method is proposed to fabricate the micro-structures of glass with low-cost, mass production and high quality by using hybrid open-mold hot embossing technology. The viscous flow and filling behaviors have a great influence on the deformation of glass micro-structures during hot embossing. The detailed topography characterizations of glass micro-structures were performed to analyze the effect of groove width, types of channel, and processing parameters (embossing temperature, pressure, and holding time) on the deformation and filling modes. The results indicated that glass micro-structures presented a larger deformation at the intersection of mold channels. The deformation ratios of glass micro-structures at the cross channels is 0.25. The larger the groove width, the larger the deformation height of the micro-structures. Also, processing parameters of temperature, pressure, and holding time are strongly correlated with the deformation profile of glass micro-structures. At the conditions of 590 °C, 5 MPa, and 100 s, the maximum aspect ratio of glass micro-structure is about 0.7. Excessive forming stress and residual stress induce the growth of glass cracking, which affects the service life and performance of glass micro-structures. This work provides a better understanding of the relationship between design and fabrication of glass micro-structures.

Analysis of dynamic back face deformation of a body armor impact by a rifle bullet using 3D-DIC

Body armor that defeats the threat can still cause severe trauma by striking the thorax with its back face deformation (BFD). In this study, the 3D digital image correlation (DIC) technology was adopted to capture the dynamic BFD of a ceramic/UHMWPE body armor impact by a rifle bullet. The shape and size of the BFD time histories, deformation velocity, acceleration and line slices profile on armor back face were obtained. The maximum BFD height can reach to 34.3 mm within about 1.2 ms, and then slowly decreases to the static deformation height of about 24mm for the impact velocity 675.4 m/s. The maximum deformation velocity and acceleration are 129.9 m/s and 1.29e6 m/s^2, respectively.

CASE STUDY REGARDING THE PREDICTION OF THE LAMINATING FORCE

Based on the mathematical model existent in the literature, the object of this study is a way to improve and simplify the way that the laminating force is determined. The whole process is realized using a provided rolling mill. The mathematical model that determines the laminating force has a theoretical base and it can approximately predict how the laminating force will vary. The relative degree of deformation tells us that de sample suffered an uneven deformation length, width and height wise. After the first lamination, the material loses plasticity and the reduction has to be as follows: higher at first, after which it drops, as the reduction degrees indicate. We created a probabilistic modelling approach that learns as new data is introduced.