Maximum Stretch Research Articles

An intelligence enhancement method for USV navigation visual measurement based on variable gradient soft-threshold correction

Maritime image enhancement is crucial in marine engineering for applications like unmanned surface vessels (USV) visual measurement and path planning. This paper proposes an image enhancement algorithm based on variable gradient soft-threshold correction (VGSC), tailored for USV intelligent navigation. By calculating the gradient of the two-dimensional difference quotient function of the pixels, we determine the pixel distribution and threshold. An innovative dynamic equalization function is applied to compress maximum pixel values and stretch minimum ones, allowing for adaptive adjustment of the threshold. The results indicate that the VGSC algorithm effectively suppresses background noise, thereby facilitating the extraction of target contour pixel information. When evaluated using four image assessment indicators, the VGSC algorithm enhances the image quality by 20.09 % and 28.92 % compared to bilateral filtering and Gamma correction, respectively. This method excels in enhancing image details and suppressing noise, promising robust application in multi-modal data fusion and precise maritime target detection.

Energy harvesting from a fiber-constrained dielectric elastomer generator embedded into a novel floating wave energy harvester

Abstract With the increasing energy demand and growing concern about greenhouse gases emissions from fossil fuel combustion, converting the ocean wave energy into the electrical energy has emerged as a promising and sustainable solution. This paper proposes a novel floating ocean wave energy harvester based on the fiber-constrained dielectric elastomer generator (DEG) arrays and investigates the energy harvesting (EH) performance of the fiber-constrained DEG embedded into the harvester. A theoretical analysis model of the fiber-constrained DEG describing the free relaxation process is developed and verified by the existing experimental data. On this basis, the electrical energy and conversion efficiency of the fiber-constrained DEG are comprehensively analyzed under diverse system parameters, aiming to explore the feasible methods for performance improvement. Results show that both the electrical energy and conversion efficiency are enhanced by shortening the cycle period, boosting the output voltage, and increasing the time ratio of the rising segment in a cycle period. Variations of the electrical energy and conversion efficiency with the input voltage exhibit the non-monotonic behavior. In addition, at low input voltage, enlarging the maximum stretch ratio improves the EH performance, while at high input voltage, the overlarge maximum stretch ratio goes against the performance improvement. The average output power of the harvester with different lengths of rods in its displacement magnifying mechanism is also investigated. Results show increasing the rod length can improve the average output power. In addition, results can help to provide a guidance for designing a high-performance DE-based floating wave energy harvester.

Fully Flexible All‐in‐One Electronic Display Skin with Seamless Integration of MicroLED and Hydrogel Battery

AbstractVisualization is a cornerstone in human–computer interaction, evolving from large screens to mobile devices and now to wearable display technology. However, conventional batteries and displays lack the softness and stretchability inherent to human skin. Here, a fully flexible, all‐in‐one electronic display skin by integrating a flexible microLED display, a stretchable circuit, and a Zn|PAM|V2O5 hydrogel battery pack is developed. Vapor‐phase bulk transfer is used to efficiently and accurately transfer 10 000 microLEDs onto a flexible substrate, ensuring high flexibility and ultra‐thin (240 µm). The flexible hydrogel battery pack provides sustainable energy, with a high specific capacity of 331.3 mAh g−1. Additionally, a transparent stretchable circuit board (maximum stretch 40%) is made by 3D printing technology. The skin display exhibited exceptional stretchability and biocompatibility, conforming to movements while maintaining high‐resolution dynamic visual outputs. These innovations pave the way for advanced skin‐implanted displays, promising transformative applications in information interaction, healthcare, and artificial intelligence.

Effects of Kinesio tape on vascularity, pliability and height of the hypertrophic scar in burns patients: a randomized pilot clinical trial.

Deep burns damage the reticular dermis and may lead to the formation of hypertrophic scars. Compression therapy reduces local vascularity and realigns collagen fibers, resulting in esthetic and functional improvements. This study evaluated the effect of Kinesio tape compression with maximum mechanical tension on vascularity, pliability and the height of hypertrophic scars following deep burns. A single blind, randomized pilot clinical trial was carried out. The elastic compression of Kinesio tape was applied at maximum stretch in the intervention group (n=11) and no stretch in the sham group (n=11). Vascularity, pliability and height (the primary outcomes) were evaluated at 0, 45 and 90 days using the Vancouver Scar Scale (VSS). The association between the VSS scores, the intervention and the evaluation moment were analyzed using linear mixed-effects regression models, while comparisons of means between the groups were performed using the t Student test was. Significance was set at 5%. The mean VSS scores were similar between the groups. Significant improvement occurred in both groups when post-treatment and baseline scores were compared. No further improvement was found in the vascularity, pliability or height of hypertrophic scars resulting from deep burns when an elastic compression of Kinesio tape was used at maximum tension compared to lesser mechanical tension.

Simple Python-Based Application for Transforming Apparent Resistivity Data from Schlumberger Configuration to Wenner Configuration Using the Linear Filter Method

Research has been conducted regarding the design of a simple Python-based application to transform apparent resistivity values ​​from the Schlumberger configuration into apparent resistivity values ​​from the Wenner configuration using the linear filter method. The application developed was then validated using field data measurements from two different locations, namely Nendali Village in the East Sentani district and Buper Waena in the Heram Jayapura district. At each measurement point, two Vertical Electrical Sounding (VES) measurements were performed using Schlumberger and Wenner configurations. The apparent resistivity values ​​from the Schlumberger configuration were transformed using the application created, and the results were compared with observational data from the Wenner configuration. Field data were taken for as many as six samples per logarithmic cycle, with the Schlumberger AB/2 configuration electrode spacing equal to the Wenner configuration electrode spacing. The maximum stretch lengths in Nendali and Buper villages were 26 m and 40 m, respectively. The research results show a match between the apparent resistivity values ​​of the Wenner configuration obtained from field observations and the transformation results. This suitability was demonstrated qualitatively through the similarity of the apparent resistivity curve trend between the transformed and field observation data. Quantitatively, this suitability is shown by the slope value of the comparison curve of field observation data and transformed data, which in Nendali and Buper Villages is 0.75 and 0.98, respectively. The conclusion of this study is that a simple application that has been designed and created can be used to transform apparent resistivity values ​​from the Schlumberger configuration to the Wenner configuration. A comparison between the transformed data and field observation data shows that suitability is highly dependent on the quality of the field data.

Study of the influence of hybrid filler on the strain sensitivity of nanocomposite material

The reflector of spacecraft is in operation in an open and folded position, so an urgent task is to develop strain gauges that determine the position of the reflector. The paper presents a study of the influence of a hybrid filler on the value of the strain resistance coefficient of a flexible strain-resistive element made of a nanocomposite material and describes the technological process of its manufacture using the vacuum infusion method. As a hybrid filler, a composition was used containing an electrically conductive component (carbon nanotubes) and a solid component (silicon carbide), which promotes uniform distribution of the filler in the polymer matrix. Using the rotational rheometer, the content of carbon nanotubes (CNTs) was determined at which the limiting level of viscosity for impregnation of glass fiber with a binder is achieved. The distribution features of the filler in the nanocomposite material were studied using a scanning electron microscope at the Krasnoyarsk Regional Center for Collective Use of the Federal Research Center KSC SB RAS. In the course of the work, the influence of the content of the hybrid filler on the tensoresistive properties of the nanocomposite material was determined. The maximum values of the tensor resistance coefficient were observed at the initial stage of the study (stretching 0.05 %): with a stretch of 0.1 mm with a total length of 200 mm for samples of nanocomposite material with a SiC hybrid filler of 1, 5 and 10 % and is 38, 40 and 40 The tensoresistance coefficient of nanocomposite material samples containing 1, 5 and 10 % SiC hybrid filler at maximum stretch (1 %) is about 19, 21 and 22, respectively.

A Chain Scission-Induced Anisotropic Damage Constitutive Model for Double Network Hydrogels

This work develops a chain scission-induced anisotropic damage constitutive model for double network (DN) hydrogels while considering the damage cross effect. A free energy of a single polymer chain comprising the configuration entropy of the polymer chain and the internal energy of persistent segments is proposed to avoid the force singularity caused by chain stretch limit. Then, a distribution function of the initial stretch ratio of polymer chains in DN hydrogels is derived to consider the randomness of chain length. Based on the micro-sphere full-network model and an energy-form fracture criterion of polymer chains, the damage evolution model of polymer chains in a certain orientation is formulated by the critical initial stretch ratio of the polymer chain, showing that only polymer chains with the initial stretch ratio lower than the critical initial stretch ratio survive in a certain chain stretch. The critical initial stretch ratio is determined by the maximum chain stretch and the maximum first invariant of the deformation state by considering the damage cross effect. Using the developed damage constitutive model, we describe the stress softening, strain hardening behavior and the nonmonotonic stress–strain curve of DN hydrogels. It also reveals that the residual strain of DN hydrogels in the loading cycles is caused by the anisotropic damage of polymer chains in DN hydrogels.

The high potential of the pure and Nb-doped δ-FeOOH (001) surface in the adsorption and degradation of a neurotoxic agent

The adsorption and degradation of the Soman molecule (Pinacolyl methylphosphonofluoridate, C7H16FO2P) was investigated using the pure and Nb-doped δ-FeOOH (001) surfaces with density functional theory (DFT) calculations. We verified the Soman molecule adsorb on pure and doped surface through interaction preferably via interaction between phosphoryl oxygen (P = O) and hydroxyl groups from surface. The degradation of the Soman molecule on the δ-FeOOH and Nb-δ-FeOOH (001) surfaces was evaluated by the study of the reaction path, were found one transition state for both surfaces, corresponding to a maximum stretch of F-P = O group from Soman molecule and the bond breaking of hydroxyl group bonded to Fe/Nb. The activation energies found are 16.58 and 8.80 kcal/mol to pure and doped surface, respectively. The obtained products consisted of a negatively charged pinacolyl methylphosphonate molecule and HF molecule adsorbed on the positively charged surface. Both δ-FeOOH and Nb-δ-FeOOH (001) surfaces show great potential to adsorb and degrade the Soman neurotoxic agent, however the presence of Nb further favors the process.

A finite element-based machine learning framework to predict the mechanical behavior of the pelvic floor muscles during childbirth

The medical community has been focusing on gaining a deeper understanding of birth trauma, which affects millions of women worldwide. Maternal lesions can be challenging to diagnose and expensive to examine. To better comprehend the mechanism of injuries occurring in the pelvic floor muscles (PFM), biomechanical simulations can be a valuable tool. However, utilizing the finite element method (FEM) to conduct simulations can be a time-consuming process. To overcome this issue, the present study aims to develop a machine learning (ML) framework to predict stresses on the PFM during childbirth by training ML algorithms on FEM simulation data. To generate the dataset for the ML algorithm’s training, childbirth simulations were performed using different material properties to characterize the PFM. Four ML algorithms were employed, namely Random Forest (RF), Extreme Gradient Boosting (XGBT), Support Vector Regression (SVR), and Artificial Neural Networks (ANN), considering two scenarios: (1) stress prediction for the maximum stretch level of the muscle, and (2) for multiple levels of fetal descent. Results showed that the ANN performed best in the former, with a mean absolute error (MAE) of 0.191 MPa. In the latter, XGBT provided lower errors for 20 and 35 mm of fetal descent, with MAE values of 0.002 and 0.028 MPa, respectively. Nevertheless, the ANN yielded better predictions for 50 and 65 mm, with MAE values of 0.214 and 0.187 MPa, respectively. The present work represents the first attempt to use FEM-based ML algorithms with childbirth simulations to obtain near-real-time predictions in routine clinical procedures.

A tough bioadhesive hydrogel supports sutureless sealing of the dural membrane in porcine and ex vivo human tissue.

Complete sequestration of central nervous system tissue and cerebrospinal fluid by the dural membrane is fundamental to maintaining homeostasis and proper organ function, making reconstruction of this layer an essential step during neurosurgery. Primary closure of the dura by suture repair is the current standard, despite facing technical, microenvironmental, and anatomic challenges. Here, we apply a mechanically tough hydrogel paired with a bioadhesive for intraoperative sealing of the dural membrane in rodent, porcine, and human central nervous system tissue. Tensile testing demonstrated that this dural tough adhesive (DTA) exhibited greater toughness with higher maximum stress and stretch compared with commercial sealants in aqueous environments. To evaluate the performance of DTA in the range of intracranial pressure typical of healthy and disease states, ex vivo burst pressure testing was conducted until failure after DTA or commercial sealant application on ex vivo porcine dura with a punch biopsy injury. In contrast to commercial sealants, DTA remained adhered to the porcine dura through increasing pressure up to 300 millimeters of mercury and achieved a greater maximum burst pressure. Feasibility of DTA to repair cerebrospinal fluid leak in a simulated surgical context was evaluated in postmortem human dural tissue. DTA supported effective sutureless repair of the porcine thecal sac in vivo. Biocompatibility and adhesion of DTA was maintained for up to 4 weeks in rodents after implantation. The findings suggest the potential of DTA to augment or perhaps even supplant suture repair and warrant further exploration.

Evaluation of graphene oxide-doped poly-lactic-co-glycolic acid (GO-PLGA) nanofiber absorbable plates and titanium plates for bone stability and healing in mandibular corpus fractures: An experimental study

BackgroundOpen reduction with internal fixation is the preferred treatment option for displaced facial bone fractures. The superior mechanical properties of metallic plates have made them the most widely used material in existing bone fixation systems. However, after the healing period, these permanent plates can cause various problems. Alternative bioresorbable materials are being investigated to reduce these potential problems. This study compares bone stability and viability by using graphene oxide (GO)-doped poly-lactic-co-glycolic acid (PLGA) nanofiber plates and titanium plates for rats with fractured mandibles. Materials and methodsThe study included 20 male Sprague-Dawley rats, divided into four groups: a control group (Group I), a mandibular fracture group with no additional application (Group II), a mandibular fracture group repaired with titanium plates (Group III), and a mandibular fracture group repaired with GO-PLGA plates (Group IV). After 2 months, all of the rats were euthanized. A bone compression test was performed to assess bone stability, and a histological examination was performed to evaluate bone healing. ResultsThe osteocyte lacunae, Haversian ducts, canaliculi, and vascular structures of Group IV were found to be higher. In the compression test, vertical compression was applied to the bone axis, and Group IV had a higher maximum load and maximum stretch. GO-PLGA plates were found to be statistically superior to titanium plates in terms of both bone stability and bone healing (p < 0.05). ConclusionsThe present study found that GO-PLGA plates are more effective than titanium plates for the treatment of mandibular corpus fractures.

Time-dependent force depreciation of intraoral orthodontic elastics of variable force and lumen sizes – An in vitro study

: To evaluate force decay of elastics of different dimensions and different force values over 48-hours.Steps included extension and immersion of elastics in artificial saliva and measurement of force levels at a specified point of time. A model with vertical pins placed at in the oral cavity. The initial force measurement was done using Universal testing machine before the elastics were engaged onto the pins 37⁰C in artificial saliva. The reading was taken after this in the Universal testing machine for the samples. The elastics were then placed back into the static simulation for the next 23 hours and again into the dynamic simulation for the next 1 hour. Statistically significant difference (P&amp;#60;0.05) was observed between force depreciation between rest and maximum stretch of the elastic. Statistically significant difference was observed in force depreciation with varying time intervals of a particular elastic sample. Lumen size and pre-determined force values affect the overall force decrease pattern of elastics. Elastics with higher force and smaller lumen size show comparatively higher loss of force than the lighter elastics with larger internal diameter. The maximum force loss of a particular elastic happens within the first 24 hours of elastic stretch. The study would help provide information about how an elastic's lumen size and initial force are interdependent, giving clinicians a better understanding of how to prescribe the right elastics for the force they need to apply for treatment.

Mechanics and microstructure of blood plasma clots in shear driven rupture.

Intravascular blood clots are subject to hydrodynamic shear and other forces that cause clot deformation and rupture (embolization). A portion of the ruptured clot can block blood flow in downstream vessels. The mechanical stability of blood clots is determined primarily by the 3D polymeric fibrin network that forms a gel. Previous studies have primarily focused on the rupture of blood plasma clots under tensile loading (Mode I), our current study investigates the rupture of fibrin induced by shear loading (Mode II), dominating under physiological conditions induced by blood flow. Using experimental and theoretical approaches, we show that fracture toughness, i.e. the critical energy release rate, is relatively independent of the type of loading and is therefore a fundamental property of the gel. Ultrastructural studies and finite element simulations demonstrate that cracks propagate perpendicular to the direction of maximum stretch at the crack tip. These observations indicate that locally, the mechanism of rupture is predominantly tensile. Knowledge gained from this study will aid in the development of methods for prediction/prevention of thrombotic embolization.

Muscle ultrasound shear wave elastography for detection of early onset lower limb ischemia in patients with veno-arterial extracorporeal membrane oxygenation

Background and objectivesLimb ischemia or compartment syndrome, requiring surgery, are some of the frequent cannula-related complications in patients supported with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). The purpose of this exploratory study is to depict and evaluate the dynamic changes in the lower limb muscles with ultrasound shear wave elastography as marker for early lower limb ischemia.MethodsEleven patients with VA-ECMO after cardiac arrest were included in this study. Seven patients received distal perfusion cannula (DPC) after implantation of the VA-ECMO, whereas 4 had no DPC after VA-ECMO. Compartment syndrome was clinically excluded in all patients. Both lower limbs, e.g., with and without arterial cannula, were monitored with near-infrared spectroscopy (NIRS) for the oxygen saturation of the local tissue. We performed ultrasound shear wave elastrography (SWE) to assess dynamic changes of the medial gastrocnemius muscle at maximum passive muscle stretch (exercise) of both legs. Color-coded duplexsonography was conducted to examine the blood flow velocity of the popliteal artery of the lower limb.ResultsWe found no difference between DPC and no DPC (p = 0.115) during use of VA-ECMO. However, we detected marked lower limb muscle perfusion deficits of cannulated (58.9 ± 13.5 kPa) vs. cannula-free limb (95.7 ± 27.9 kPa: p < 0.001), applying SWE. No relationship was detected between NIRS measurements and SWE values (kPa) of both lower limbs. The mean peak systolic velocity of the popliteal artery at the cannulated side (30.0 ± 11.7 cm/s) was reduced compared to the non-cannulated side (39.3 ± 18.6 cm/s; p = 0.054).ConclusionsRegardless of DPC after implantation of VA-ECMO, the gastrocnemius muscles seem to lose function due to cannula-related microcirculatory deficits. Muscle function analysis via SWE combined with NIRS might offer a sensitive indicator for early onset leg ischemia during VA-ECMO-related arterial cannulation.

A Sterile, Injectable, and Robust Sericin Hydrogel Prepared by Degraded Sericin.

The application of sericin hydrogels is limited mainly due to their poor mechanical strength, tendency to be brittle and inconvenient sterilization. To address these challenges, a sericin hydrogel exhibiting outstanding physical and chemical properties along with cytocompatibility was prepared through crosslinking genipin with degraded sericin extracted from fibroin deficient silkworm cocoons by the high temperature and pressure method. Our reported sericin hydrogels possess good elasticity, injectability, and robust behaviors. The 8% sericin hydrogel can smoothly pass through a 16 G needle. While the 12% sericin hydrogel remains intact until its compression ratio reaches 70%, accompanied by a compression strength of 674 kPa. 12% sericin hydrogel produce a maximum stretch of 740%, with breaking strength and tensile modulus of 375 kPa and 477 kPa respectively. Besides that, the hydrogel system demonstrated remarkable cell-adhesive capabilities, effectively promoting cell attachment and, proliferation. Moreover, the swelling and degradation behaviors of the hydrogels are pH responsiveness. Sericin hydrogel releases drugs in a sustained manner. Furthermore, this study addresses the challenge of sterilizing sericin hydrogels (sterilization will inevitably lead to the destruction of their structures). In addition, it challenges the prior notion that sericin extracted under high temperature and pressure is difficult to directly cross-linked into a stable hydrogel. This developed hydrogel system in this study holds promise to be a new multifunctional platform expanding the application area scope of sericin.

A biomechanical perspective on perineal injuries during childbirth

Background and ObjectiveChildbirth trauma is a major health concern that affects millions of women worldwide. Severe degrees of perineal trauma, designated as obstetric anal sphincter injuries (OASIS), and levator ani muscle (LAM) injuries are associated with long-term morbidity. While significant research has been conducted on LAM avulsions, less attention has been given to perineal trauma and OASIS, which affect up to 90% and 11% of vaginal deliveries, respectively. Despite being widely discussed, childbirth trauma remains unpredictable. This work aims to enhance the modeling of the maternal musculature during childbirth, with a particular focus on understanding the mechanisms underlying the often overlooked perineal injuries. MethodsA geometrical model of the pelvic floor muscles (PFM) and perineum (including the perineal body, ischiocavernosus, bulbospongiosus, superficial and deep transverse perineal muscles) was created. The muscles were characterized by a transversely isotropic visco-hyperelastic constitutive model. Two simulations of vaginal delivery were conducted with the fetus in the vertex presentation and occipito-anterior position, with and without the perineum. ResultsThe simulation that considered the perineum exhibited higher stresses over an extended area of the PFM, which suggests that including additional structures can impact the obtained results. The maximum stretch of the urogenital hiatus was 2.94 and the maximum stress was 23.86 kPa. The perineal body reached a maximum stretch of 1.95, which was more pronounced near the urogenital hiatus, where perineal tears may occur. The external anal sphincter's transverse diameter decreased by 51% and the maximum principal stresses were observed in the area close to the perineal body, where OASIS can occur. ConclusionsThe present study emphasizes the importance of including most structures involved in vaginal delivery in its biomechanical analysis and represents another step further in the understanding of perineal injuries and OASIS. The superior region of the perineal body and its connection to the urogenital hiatus and anal sphincter have been identified as the most critical regions, highly susceptible to injury.

Influence of print settings on conductivity of 3D printed elastomers with carbon-based fillers

Flexible, elastomeric materials for 3D printing have attracted considerable interest due to their potential application in clothing, shoe manufacturing and orthopedics. At the same time, smart clothing is also moving closer to more mainstream applications; as such, it is of considerable interest to combine both the structural and smart functions 3D printing offers in one material. While smart functionalities may be incorporated in a textile in a variety of ways (e.g. using shape-memory polymers), the use of electronic components such as sensors and actuators allow smart response to a multitude of stimuli. This necessitates the use of conductive and flexible materials that offer reliable conductivity after printing and provide optically attractive results. It is known that print conditions influence electrical properties, but while the print parameters are well researched for hard materials, there is not as much research for flexible compounds. Here, we show the influence of print speed, temperature, infill orientation, layer thickness and print mode (i.e. time between printing of successive layers). It was found that the most influential parameters are print mode, infill orientation and print temperature. The differences in electrical properties between the three materials used in this test may be explained by differences in filler content. A preliminary study into the optimization of the shape of a printed conductive line on elastic textile shows that the overall length of the printed path needs to be adapted to the maximum stretch of the textile, while shape has little influence on conductivity.

Predicting the expansion of the lower pole of the breast following smooth breast implant augmentation: A novel shear wave elastography study

This study aimed to educate and demonstrate how the use of shear wave elastography (SWE) can be used to determine the elasticity of patient tissues preoperatively, which can then be used to predict the level of lower pole expansion postoperatively, following breast augmentation surgery. This study evaluated 60 breasts in 30 patients that were divided in 3 equal groups (n=20) according to their predefined elastography criteria measured via SWE (loose, moderate, and tight tissue elasticity). All measurements were taken under maximum stretch between the inferior border of the nipple alveolar complex (NAC) and inframammary fold (IMF) using a measuring tape in millimetres (mm). The follow-up appointments for routine assessments and measurements were done at 3, 6, 12, 18, and 24 months. The study engaged 38 patients over 4 years, but only 10 patients in each group attended all the appointments. Statistical analysis showed the elastic skin types (loose, moderate, and tight) had significantly different rates of lower pole expansion, and the rate of expansion increased significantly after 6 months postoperatively, whereas prior to 6 months, the rates were comparable (p<0.05). The results showed that increasingly elastic skin types have a greater rate of lower pole expansion. This is important for the operating surgeon to be aware of as looser skin types will be more prone to lower pole expansion, and thus, a higher surgical IMF suture may be advised to manage patient expectations. This study can be used as a guideline for surgeons, which will allow for a more predictable surgical planning system that will ultimately lead to fewer revisions and risks for patients worldwide.

Fiber Bragg grating sensor combined with silicone compliant cylinder for orientation identification of three-component geophone

Three-component geophone rotates randomly during oil and gas exploration, which is difficult to orient. There is a severe impact on the subsequent stratigraphic inversion. By fixing the fiber Bragg grating (FBG) sensor to the three-component geophone, the twist angle is the same. The rotation angle of the three-component geophone can be obtained by measuring the twist angle of the FBG sensor. However, the three-component geophone below the FBG sensor stretches the FBG sensor. Therefore, avoiding the effect of tensile strain on the torsional strain, requires simultaneous inversion of the twist angle and stretch length of the FBG sensor. This paper introduces an FBG sensor with simultaneous inversion of torsion angle and tensile length. The sensor consists of two FBGs embedded in the spiral groove of the compliant cylinder. Firstly, the sensing principle of the FBG sensor is analyzed, and developed FBG sensing model for tensile–torsional strain, including FBG by tilting arrangement, the extension of the tensile strain range of the FBG sensor was realized. Secondly, it describes the fabrication process of the FBG sensor, including loading the FBG with pre-stress, making the FBG sensor realize the extension of the torsion angle range. Next, the convenience of inversion is realized by averaging the calibrated strain transfer coefficients. Finally, to verify the effectiveness of this bidirectional helical fiber design and sensing technology, simultaneous torsion and tension tests were conducted on FBG sensors. The experimental results show that the sensor achieves simultaneous torsion angle and tensile length inversion. The maximum torsion angle of the inversion is 180°. The maximum stretch length of the inversion is 10 mm.

The optimization design of pre-forming for forging automobile parts using Taguchi method based grey relational analysis

This study used finite element analysis software DEFORM-3D to analyze the preform formability and die stress in the pre-forming process of forging automobile transmission components. The preform and die materials used are AISI- 5120 alloy steel and JIS-SKD61 mould steel, respectively. This research investigated the phenomenon of folding defects in the preform at the end of the final forging process. First, as the die shape under the pre-formed channel was designed to change, its die shape was close to the final forged hole shape. Then, three quality characteristics were optimally analyzed by the Taguchi method for pre-formed passes, namely, “maximum tensile stress of the upper die, ”“maximum stretch stress of the lower die, ” and “ the degree of filling of the preform in the die cavity.” Then, this study applied grey correlation analysis to identify the experimental parameter configuration that could achieve a balance between the three quality characteristics, as compared with the results obtained by the Taguchi method. The results show that the lower die after the design change of the pre-forming pass can indeed improve the phenomenon of folding defects in the preform. In terms of the overall experimental data, the experimental data obtained by grey correlation analysis can balance the experimental results of the Taguchi method based on the optimization of the three quality characteristics. The experimental result of this set of parameters not only obtained the maximum tensile stress value of 716.614 MPa in the upper die but also considered the degree of the preform filling and maximum tensile stress in the lower die. The two values were 102.56% and 836.843 MPa. Although these two values are not optimal, compared to the data obtained by the Taguchi method, the preform was filled completely in this case. The maximum tensile stress value of the lower die is also the lowest.