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Engineering slope stability issues typically exhibit the impact of deteriorating durability on the susceptibility of slopes to failure. A thorough investigation was essential to explore theoretical and experimental aspects of slope durability degradation and its implications on long-term stability. Hence, a durability model was developed to accommodate slope stabilization using reinforced concrete (RC) support structures. This model was grounded in classical durability principles for RC structures. Subsequently, a model test was conducted to compare the responses of a standard slope model with a weakened counterpart subjected to environmental impacts. According to the proposed methodology for slope durability and stability, a case study involving future durability and stability predictions was performed. It was found that the theoretical solutions for the carbonation or neutralization (CN) velocity, depth, and penetration time agreed well with model test results. The slope surface displacements of the weakened slope with deteriorating coefficients between 0.6 and 0.9 were 4 to 8 times those of the standard slope, demonstrating significant degradation in stability. The case study indicated a steady reduction in the safety factor, at a rate of 2.3 to 2.4‰ per year throughout the slope's service life. Finite-element-based predictions also suggested the potential for corrosion of slope anchor bolts within 20 years and breakage within 30 years, at an average rate of 7.5‰ per year in the ultimate bearing capacity. These findings highlight the need for timely maintenance and reinforcement interventions to ensure the long-term durability of operational slopes.

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Honeycomb structures made of carbon-fiber-reinforced plastic (CFRP) are increasingly used in the aerospace field due to their excellent energy absorption capability. Attention has been paid to CFRP structures in order to accurately simulate their progressive failure behavior and discuss their ply designability. In this study, the preparation process of a CFRP corrugated sheet (half of the honeycomb structure) and a CFRP honeycomb structure was illustrated. The developed finite element method was verified by a quasi-static test, which was then used to predict the low-velocity impact (LVI) behavior of the CFRP honeycomb, and ultimately, the influence of the ply angle and number on energy absorption was discussed. The results show that the developed finite element method (including the user-defined material subroutine VUMAT) can reproduce the progressive failure behavior of the CFRP corrugated sheet under quasi-static compression and also estimate the LVI behavior. The angle and number of plies of the honeycomb structure have an obvious influence on their energy absorption under LVI. Among them, energy absorption increases with the ply number, but the specific energy absorption is basically constant. The velocity drop ratios for the five different ply angles are 79.12%, 68.49%, 66.88%, 66.86%, and 60.02%, respectively. Therefore, the honeycomb structure with [0/90]s ply angle had the best energy absorption effect. The model proposed in this paper has the potential to significantly reduce experimental expenses, while the research findings can provide valuable technical support for design optimization in aerospace vehicle structures.

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This paper describes a novel bearingless split tooth flux reversal motor with integrated centrifugal blood pump. This motor has a magnet-free rotor, and is capable of operating at up to 3000 rpm with up to 100 mNm torque. The motor also has 50 N radial force capability for centering the rotor. The motor rotor is 50 mm diameter, housed in a 170mm wide stator. The motor has a novel magnetic configuration wherein the force generation is independent of the rotor angle. This allows simple radial force generation using stator-fixed currents. The motor torque is generated using commutated two-phase currents. Finite element simulations are used to optimize the design in order to achieve sufficient radial force and motor torque, while minimizing cogging torque. The design also achieves an axial passive magnetic stiffness of 5.4 N/mm, which is the constraint on axial motions of the rotor. This paper includes mechanical design and fabrication details, as well as experimental closed loop levitation and speed control performance. With an integrated impeller, the rotor and the centrifugal pump are tested by pumping fluid in a closed circuit to obtain experimental pressure-flow curves with impeller-limited performance.

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The rise in additive manufacturing (AM) offers myriad opportunities for 3D-printed polymeric vascular scaffolds, such as customization and on-the-spot manufacturing, in vivo biodegradation, incorporation of drugs to prevent restenosis, and visibility under X-ray. To maximize these benefits, informed scaffold design is critical. Polymeric bioresorbable vascular scaffolds (BVS) must undergo significant deformation prior to implantation in a diameter-reduction process known as crimping which enables minimally invasive surgery. Understanding the behavior of vascular scaffolds in this step provides twofold benefits: first, it ensures the BVS is able to accommodate stresses occurring during this process to prevent failure, and further, it provides information on the radial strength of the BVS, a key metric to understanding its post-implant performance in the artery. To capitalize on the fast manufacturing speed AM provides, a low time cost solution for understanding scaffold performance during this step is necessary. Through simulation of the BVS crimping process in ABAQUS using experimentally obtained bulk material properties, we have developed a qualitative analysis tool which is capable of accurately comparing relative performance trends of varying BVS designs during crimping in a fraction of the time of experimental testing, thereby assisting in the integration of informed design into the additive manufacturing process.

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Hallux valgus is a common foot deformity characterized by outward tilting and twisting of the big toe, often accompanied by a medial prominence at the base. Minimally invasive surgical techniques are widely utilized for treating metatarsus adductus due to their advantages of smaller incisions, faster recovery, and early weight-bearing. However, due to individual variations and limited sample size, the biomechanical effects of different Kirschner wire fixation methods and the underlying mechanisms of postoperative metatarsalgia remain unclear. In this study, a finite element method was employed to develop a biomechanical model of metatarsus adductus. The influence of various Kirschner wire entry points and angles on foot loading characteristics was investigated. Six different Kirschner wire fixation models, including two entry methods (along the adjacent fracture line and proximal-biased entry at the midshaft of the metatarsal) with different entry angles, were analyzed. Mechanical parameters such as metatarsal stress distribution, plantar pressure distribution, and displacement of the first metatarsal osteotomy plane were assessed. This research aims to enhance understanding of minimally invasive surgery and its fixation methods for metatarsus adductus. By providing scientific support and reliable evidence, it seeks to contribute to the development of minimally invasive surgical techniques and the improvement of clinical practice in metatarsus adductus surgery. Ultimately, the goal is to reduce complications, increase surgical success rates, and enhance patient satisfaction.

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The continuous development and application of laser technology, and the increasing energy and power of laser output have promoted the development of various types of laser optical systems. The optical components based on quartz materials are key components of high-power laser systems, and their quality directly affects the load capacity of the system. Due to the photothermal effect when the laser interacts with the quartz material and generates extremely high temperatures in a short period of time, it is impossible to experimentally solve the phenomena and physical mechanisms under extreme conditions. Therefore, it is very important to select a suitable method to investigate the thermal effect of intense laser interaction with quartz materials and explain the related physical mechanism. In this study, a three-dimensional quarter-symmetric laser heating quartz material geometry model by using nonlinear transient finite element method was established, and its transient temperature field distribution of the quartz material after being heated by a 1,064 nm continuous laser was investigated. In addition, the influence of different laser parameters (laser spot radius, heat flux and irradiation time), material parameters (material thickness, material absorption rate of laser) on the thermal effect of heating quartz material were also studied. When the laser heat flux is 20 W/cm2, the diameter of the laser spot is 10 cm, the irradiation time is 600 s and the thickness is 4 cm, the temperature after laser heating can reach 940.18°C, which is far lower than the melting point. In addition, the temperature maximum probes were set at the overall model, spot edge and rear surface respectively, and their temperature rise curves with time were obtained. It is also found that there is a significant hysteresis period for the rear surface temperature change of the quartz material compared with the overall temperature change due to heat conduction. Finally, the method proposed can also be applied to the laser heating of other non-transparent materials.

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Existing optimization research on the crankshaft heat treatment process is mostly based on one-sided considerations, and less consideration is given to the matching of multiple process parameters, leading to irrational designs of heat treatment. To address this problem, this work investigates the influence mechanisms of cooling speed, tempering temperature, and holding time on the performance evaluation indexes of the straightness, residual stress, and martensite content of a crankshaft based on the response surface method. The results showed that the order of influence of these three different process parameters on the performance evaluation index was cooling speed > holding time > tempering temperature, and the order of influence on the performance evaluation indexes under multifactorial process parameters was cooling speed-holding time > cooling speed-tempering temperature > holding time-tempering temperature. The optimal process parameters were a cooling speed of 1.4 times the cooling oil, a tempering temperature of 555 °C, and a holding time of 6 h, with the straightness of the crankshaft reduced by 9.9%, the surface stress increased by 6.7%, and the martensitic content increased by 7.2% after the process optimization. This work can provide new clues for optimizing the heat treatment process parameters of crankshafts.

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Pure titanium is a preferred material for medical applications due to its outstanding properties, and the fabrication of its surface microtexture proves to be an effective method for further improving its surface-related functional properties, albeit imposing high demands on the processing accuracy of surface microtexture. Currently, we investigate the fabrication of precise microtextures on pure titanium surfaces with different grid depths using precision-cutting methods, as well as assess its impact on surface wettability through a combination of experiments and finite element simulations. Specifically, a finite element model is established for pure titanium precision cutting, which can predict the surface formation behavior during the cutting process and further reveal its dependence on cutting parameters. Based on this, precision-cutting experiments were performed to explore the effect of cutting parameters on the morphology of microtextured pure titanium with which optimized cutting parameters for high-precision microtextures and uniform feature size were obtained. Subsequent surface wettability measurement experiments demonstrated from a macroscopic perspective that the increase in the grid depth of the microtexture increases the surface roughness, thereby enhancing the hydrophilicity. Corresponding fluid-solid coupling finite-element simulation is carried out to demonstrate from a microscopic perspective that the increase in the grid depth of the microtexture decreases the cohesive force inside the droplet, thereby enhancing the hydrophilicity.

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The comprehensive performance of rubber products could be significantly improved by the addition of functional fillers. To improve research efficiency and decrease the experimental cost, the mechanical and thermal properties of carbon-fiber-reinforced rubber were investigated using finite element simulations and theoretical modeling. The simplified micromechanical model was constructed through the repeatable unit cell with periodic boundary conditions, and the corresponding theoretical models were built based on the rule of mixture (ROM), which can be treated as the mutual verification. The simulation results suggest that, in addition to the fiber volume fraction Vfc increasing from 10% to 70%, the longitudinal Young's modulus, transversal Young's modulus, in-plane shear modulus, longitudinal thermal expansion coefficient, and transversal thermal expansion coefficient changed from 2.31 × 1010 Pa to 16.09 × 1010 Pa, from 0.54 × 107 Pa to 2.59 × 107 Pa, from 1.66 × 106 Pa to 10.11 × 106 Pa, from -4.98 × 10-7 K-1 to -5.89 × 10-7 K-1, and from 5.72 × 10-4 K-1 to 1.66 × 10-4 K-1, respectively. The mechanism by which Vfc influences the properties of carbon-fiber-reinforced rubber was revealed through the distribution of Von Mises stress. This research will contribute to improving the performance of carbon-fiber-reinforced rubber and promote its application.

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Metal composite parts are widely used in different industries owing to their significant improvement in material properties, such as mechanical strength, electrical conductivity, and corrosion resistivity, compared to traditional single metals. Such composite parts can be manufactured and processed in different ways to achieve the desired geometry and quality. Among various metal forming techniques, drawing is the most commonly used process to produce long composite wires or rods from raw single materials. During the drawing process of composite wires or rods, not only does the core radius ratio change, but the core or sleeve layer may also undergo necking or fracture due to excessive tensile stresses in the softer layer. In this paper, bimetallic rods with AISI-1006 low-carbon steel cores and C10100 oxygen-free electronic copper sleeves are modeled using the finite element software DEFORM. The simulation models are verified by drawing experiments. The effects of initial bonding conditions, the initial core ratio, reduction ratio, semi-die angle, drawing speed, and friction on the plastic deformation behavior of the bimetallic rods are investigated. The results indicate that the initial bonding conditions have a great impact on the deformation behavior of the billets in terms of strain distribution, material flow, residual stress, and the final core ratio. The permissible forming parameters for obtaining a sound product are investigated as well. With the aid of these analyses, the drawing process and the quality of the products can be controlled steadily.

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We are developing a phase-modulating micro mirror-array spatial light modulator to be used for real holography within the EU-funded project REALHOLO, featuring millions of pixels that can be individually positioned in a piston mode at a large frame rate. We found earlier that an electrostatic comb-drive array offers the best performance for the actuators: sufficient yoke forces for fast switching even at low voltages compatible with the CMOS addressing backplane. In our first design, the well-known electrostatic cross-talk issue had already been much smaller than would have been possible for parallel-plate actuators, but it was still larger than the precision requirements for high-image-quality holography. In this paper, we report on our analysis of the crucial regions for the electrostatic cross-talk and ways to reduce it while observing manufacturing constraints as well as avoiding excessively high field strengths that might lead to electrical breakdown. Finally, we present a solution that, in FEM simulations, reduces the remaining cross-talk to well below the required specification limit. This solution can be manufactured without any additional processing steps and suffers only a very small reduction of the yoke forces.

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How to raise the bridge barrier with a concrete base height of only 51 cm to SS level of protection is not yet studied. In order to effectively retrofit an existing concrete barrier design to meet new crash testing criteria, the structural dimensions and concrete strength of the existing bridge barrier were investigated, and finite element simulation analysis was carried out, and simulation suggested the existing barrier was insufficient. Based on the structural dimension design principles of bridge barriers, the existing structure of bridge barrier was designed after adding lightweight and high-strength B750HL material crossbeams and posts on top of the concrete base, and the bearing capacity of the bridge barrier was calculated based on the yield line theory. Then, a finite element simulation analysis model was established to study and analyze the blocking, guiding, and cushioning functions of the improved design of bridge barrier. Finally, full-scale-vehicle crash tests were conducted with the SS-level small car, bus, and tractor-van trailer for this bridge barrier design scheme. This paper is the world's first to use B750HL steel as the material for the crossbeam and post of a bridge barrier with a concrete base height of only 51 cm. According to the research results, the B750HL bridge barrier, which was designed based on the calculation of structural dimension design and yield line theory, effectively reduces the increased constant load on the bridge deck caused by the extra crossbeams and posts. At the same time, it can reduce material costs and save engineering costs. After being verified by finite element simulation crash tests and full-scale-vehicle crash tests, the protective capacity of the B750HL bridge barrier was proven to meet the SS-level evaluation requirements of the Standard for Safety Performance Evaluation of Highway Barriers (JTG B05-01-2013). The research findings of this paper is that the finite element simulation crash tests can effectively simulate full-scale-vehicle crash test, and the finite element simulation crash tests is reliable. If the safety performance of the barrier in the finite element simulation crash tests meets the requirements, the probability of passing the full-scale-vehicle crash test is higher. Therefore, a design scheme is proposed for the B750HL bridge barrier to improve hybrid bridge barriers at a height of 51 cm or more based on various design methods.

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Falls among the elderly cause a huge number of hip fractures worldwide. Energy absorbing floors (EAFs) represent a promising strategy to decrease impact force and hip fracture risk during falls. Femoral neck force is an effective predictor of hip injury. However, the biomechanical effectiveness of EAFs in terms of mitigating femoral neck force remains largely unknown. To address this, a whole-body computational model representing a small-size elderly woman with a biofidelic representation of the soft tissue near the hip region was employed in this study, to measure the attenuation in femoral neck force provided by four commercially available EAFs (Igelkott, Kradal, SmartCells, and OmniSports). The body was positioned with the highest hip force with a -10∘ trunk angle and +10∘ anterior pelvis rotation. At a pelvis impact velocity of 3 m/s, the peak force attenuation provided by four EAFs ranged from 5% to 19%. The risk of hip fractures also demonstrates a similar attenuation range. The results also exhibited that floors had more energy transferred to their internal energy demonstrated greater force attenuation during sideways falls. By comparing the biomechanical effectiveness of existing EAFs, these results can improve the floor design that offers better protection performance in high-fall-risk environments for the elderly.

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BACKGROUND: In recent years, intravascular micro-axial blood pumps have been increasingly used in the treatment of patients with cardiogenic shock. The flow rate of such blood pumps requires adjustment based on the patient's physiological condition. Compared to a stable flow state with fixed rotation speed, adjusting the speed of blood pump impeller to alter flow rate may lead to additional hemolysis. This study aimed at elucidating the relationship between adjusting interval of a blood pump's impeller speed and the hemolysis index. METHODS: By comparing simulation results with P-Q characteristic curves of the blood pump measured by experiments, the accuracy of the blood pump flow field simulation model was confirmed. In this study, a drainage tube was employed as the device analogous to an intravascular micro-axial blood pump for achieving similar shear stress levels and residence times. The hemolysis finite element prediction method based on a power-law model was validated through hemolysis testing of porcine blood flow through the drainage tube. The validated models were subsequently utilized to investigate the impact of impeller speed adjusting intervals on hemolysis in the blood pump. RESULTS: Compared to steady flow, the results demonstrate that the hemolysis index increased to 6.3% when changing the blood pump flow rate from 2 L/min to 2.5 L/min by adjusting the impeller speed within 0.072 s. CONCLUSIONS: An adjustment time of impeller speed longer than 0.072 s can avoid extra hemolysis when adjusting the intravascular micro-axial blood pump flow rate from 2 L/min to 2.5 L/min.

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Converting otherwise wasted kinetic energy present in the environment into usable electrical energy to power wireless sensor nodes, is a green strategy to avoid the use of batteries and wires. Most of the energy harvesters presented in the literature are based on the exploitation of a one-degree-of-freedom arrangement, consisting of a tuned spring-mass system oscillating in the main direction of the exciting vibration source. However, if the direction of excitation changes, the efficiency of the harvester decreases. This paper thus proposes the idea of a curved cantilever beam with a two-degree-of-freedom arrangement, where the two bending natural frequencies of the mechanical resonator are designed to be equal. This is thought to lead to a configuration design that can be used in practical circumstances where excitation varies its direction in the plane. This, in turn, may possibly lead to a more effective energy-harvesting solution to power nodes in a wireless sensor network.

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The continuously reinforced concrete pavement (CRCP) system grapples with challenges such as non-uniform transverse crack patterns and the need for substantial reinforcement. Field research on the Belgian CRCP sections along motorway E313 indicates that active cracking induced by partial surface saw-cuts consistently leads to transverse crack patterns. This study introduces an innovative modification to the CRCP: the actively reinforced concrete pavement design (ARCP). The ARCP leverages partial surface saw-cuts to reduce reinforcement needs by replacing continuous-length steel bars with partial-length counterparts. The main objective of the present study is to develop a 3D finite element (FE) model capturing the active cracking behavior of ARCP under realistic external temperature variations. Comparative analysis with CRCP considers early-age crack patterns, crack strain development, and the distribution of maximum steel stress for different steel ratios (0.67%, 0.75%, and 0.85%). FE simulation results align with field data, indicating that ARCP exhibits similar early-age cracking behavior to CRCP but with a significant 24 to 42% reduction in total reinforcement. This innovation presents a promising avenue for addressing CRCP challenges while optimizing material usage in pavement construction.

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The welding effect of the laser on skin tissue is reduced by thermal damage to skin tissue, and greater thermal damage to skin tissue caused by the laser is prevented by predicting thermal damage. In this paper, a finite element model is established for the temperature field of skin tissue scanned by a femtosecond laser to obtain the influence of laser process parameters and scanning path on the thermal damage parameters of skin tissue and the thermal damage area, and verified experimentally. The results show that the established finite element model is accurate and can accurately reflect the temperature distribution during the process of femtosecond laser welding of porcine skin tissues; used to predict the thermal damage parameters of the skin tissues and the thermal damage area; and provide guidance for the study of the femtosecond laser welding of the skin tissues process to obtain the optimal process parameters.

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Ultrasound backscatter coefficient (BSC) measurement is a method for assessing tissue morphology that can inform on pathologies such as cancer. The BSC measurement is, however, limited by the accuracy with which the investigator can normalise their results to account for frequency dependent effects of diffraction and attenuation whilst performing such measurements. We propose a simulation-based approach to investigate the potential sources of error in assessing the BSC. Presented is a tool for the 2D Finite Element (FE) simulation mimicking a BSC measurement using the planar reflector substitution method in reduced dimensionality. The results of this are verified against new derivations of BSC equations also in reduced dimensionality. These new derivations allow computation of BSC estimates based on the scattering from a 2D scattering area, a line reference reflector and a theoretical value for the BSC of a 2D distribution of scatterers. This 2D model was designed to generate lightweight simulations that allow rapid investigation of the factors associated with BSC measurement, allowing the investigator to generate large data sets in relatively short time scales. Under the conditions for an incoherent scattering medium, the simulations produced BSC estimates within 6% of the theoretical value calculated from the simulation domain, a result reproduced across a range of source f-numbers. This value of error compares well to both estimated errors from other simulation based approaches and to physical experiments. The mathematical and simulation models described here provide a theoretical and experimental framework for continued investigation into factors affecting the accuracy of BSC measurements.

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Since their invention, tissue expanders, which are designed to trigger additional skin growth, have revolutionised many reconstructive surgeries. Currently, however, the sole quantitative method to assess skin growth requires skin excision. Thus, in the context of patient outcomes, a machine learning method which uses non-invasive measurements to predict in vivo skin growth and other skin properties, holds significant value. In this study, the finite element method was used to simulate a typical skin expansion protocol and to perform various simulated wave propagation experiments during the first few days of expansion on 1,000 individual virtual subjects. An artificial neural network trained on this dataset was shown to be capable of predicting the future skin growth at 7 days (avg. R 2 = 0.9353 ) as well as the subject-specific shear modulus ( R 2 = 0.9801 ), growth rate ( R 2 = 0.8649 ), and natural pre-stretch ( R 2 = 0.9783 ) with a very high degree of accuracy. The method presented here has implications for the real-time prediction of patient-specific skin expansion outcomes and could facilitate the development of patient-specific protocols.

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OBJECTIVE: Intravascular lymphatic valves often occur in proximity to vessel junctions. It is commonly held that disturbed flow at junctions is responsible for accumulation of valve-forming cells (VFCs) at these locations as the initial step in valve creation, and the one which explains the association with these sites. However, evidence in favor is largely limited to cell culture experiments. METHODS: We acquired images of embryonic lymphatic vascular networks from day E16.5, when VFC accumulation has started but the developing valve has not yet altered the local vessel geometry, stained for Prox1, which co-localizes with Foxc2. Using finite-element computational fluid mechanics, we simulated the flow through the networks, under conditions appropriate to this early development stage. Then we correlated the Prox1 distributions with the distributions of simulated fluid shear and shear stress gradient. RESULTS: Across a total of 16 image sets, no consistent correlation was found between Prox1 distribution and the local magnitude of fluid shear, or its positive or negative gradient. CONCLUSIONS: This, the first direct semi-empirical test of the localization hypothesis to interrogate the tissue from in vivo at the critical moment of development, does not support the idea that a feature of the local flow determines valve localization.

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