High Overload Conditions Research Articles

Simulation and optimization of fuze circuit housing structural strength under a high overload environment

Abstract With the continuous improvement of modern military equipment protection systems, the demand for ammunition to penetrate hard targets has become increasingly apparent. The projectile is subjected to a high overload environment during launching and penetrating hard targets. Fuze as the detonation control system of the projectile, is prone to significant deformation or even damage to its circuit housing structure in a high overload environment. The dynamic response of fuze circuit housing under high overload conditions is analyzed, and the housing structure is further optimized according to the simulation results to ensure that the fuze circuit housing can meet the strength requirements under a high overload environment.

A MEMS Disk Gyroscope with High Fabrication Precision, High Quality Factor (>810k) and High Overload Characteristic (>15000g)

This paper presents an electromagnetic MEMS disk gyroscope based on fused silica to enhance the accuracy of MEMS gyros under high overload conditions. A laser-induced modified wet etching (LIE) technology was utilized for gyro fabrication and a detailed analysis was conducted on the factors affecting quality factor (Q-value) of the gyro. The LIE process parameters were optimized using a four-factor and three-level orthogonal experiment, and structure compensation were implemented to address machining errors. Impact capability of the resonator and mode characterization as well as Q-value of the gyro revealing that the resonator can withstand high overload up to 15000g, frequency of working mode is 15382.2Hz and 15379.8Hz, respectively, which close to simulated result of 15443Hz exhibited high process precision. The corresponding Q-values of the driving mode and sensing mode are 817k and 819k, respectively, indicating high-performance potential.

Real-Time Attitude Estimation for Spinning Projectiles by Magnetometer Based on an Adaptive Extended Kalman Filter.

The attitude measurement system based on geomagnetic information offers advantages such as small space requirements, fast response times, excellent resistance to high-overload conditions, and cost-effectiveness. However, during the flight process of a high-mobility guided spinning projectile, calculating attitude based on geomagnetic information often leads to non-unique solutions. To address this challenge, this paper proposes the Adaptive Extended Kalman Filter (AEKF) attitude estimation algorithm, based on geomagnetic vector information. Based on the analysis of the short-term attitude motion characteristics of the projectile, the Kalman state system equation and the nonlinear observation equation are established, along with real-time correction of the yaw angle and adaptive updates of parameters. The effectiveness of the algorithm is verified by simulations and experiments, demonstrating its ability to eliminate the dual solution problem inherent in traditional Single-Epoch algorithms. It notably improves the accuracy of pitch and roll angle estimation while providing precise estimates of attitude angular rates. Furthermore, the algorithm effectively mitigates the impact of magnetic disturbances on attitude determination. The proposed method has many potential applications in attitude measurement and navigation using geomagnetic data.

Failure mode analysis of electronic detonator under high overload condition

Under different overload conditions, the split Hopkins method was used to test the high overload performance of the electronic detonator and the failure status of each electronic detonator component was obtained. The results show that the power supply function of the electronic control module in the delayed state has a short failure when the starting value of overload is 6.23 ten thousand g, and the greater the overload, the more obvious the failure. When the overload increases to 38.10 ten thousand g, the communication function of the electronic control module fails. When the overload increases to 46.62 ten thousand g, the riveting part is still firm without failure.

Overload performance study and fabrication of the capacitive pressure-sensitive chip with linkage film.

In order to satisfy the demands of pressure measurement under high overload conditions, the overload characteristics of the capacitive pressure-sensitive chip with linkage film are studied. Through the simulation and analysis for the stress distribution of this sensitive structure and in light of the dimension effect of the tensile strength of monocrystalline silicon, the influence of sizes of the sensitive structure on the overload pressure is expounded. The simulated results illustrate that the maximum overload pressure can exceed 200 times the full-scale (FS) when appropriately adjusting the sizes of the sensitive structure. The proposed chip is fabricated using SOI wafers combined with bonding technology. Our experimental results show that the sample chip has a linear response in the pressure range of 25-100kPa, and its overload pressure is 4.5 MPa, reaching 45 times the full-scale.

Lumped-Parameters Thermal Network of PM Synchronous Machines for Automotive Brake-by-Wire Systems

Thermal analysis represents a key factor in electrical machine design due to the impact of temperature increase on insulation lifetime. In this context, there has been a wide investigation on thermal modeling, particularly for machines used in harsh working conditions. In this perspective, brake-by-wire (BBW) systems represent one of the most challenging applications for electrical machines used for automotive smart actuators. Indeed, electro-actuated braking systems are required to repeatedly operate the electric machine in high overload conditions in order to limit the actuator response time, as well as to enhance gravimetric and volumetric specific performance indexes. Moreover, BBW systems often impose unconventional supply conditions to the electric machine, consisting of dc currents in three-phase windings to keep the rotor fixed during the braking intervals. However, a dc supply leads to uneven temperature distributions in the machine, and simplified thermal models may not accurately represent the temperature variations for the different machine parts. Considering such unconventional supply conditions, this paper initially investigates the applicability of a conventional lumped-parameters thermal network (LPTN) based on symmetry assumptions for the heat paths and suitable for surface-mounted PM synchronous machines used in BBW systems. An extensive test campaign consisting of pulses and load cycle tests representative of the real machine operations was conducted on a prototype equipped with several temperature sensors. The comparison between measurements and predicted average temperatures, together with insights on the unbalanced heat distribution under the dc supply obtained by means of finite element analyses (FEA), paved the way for the proposal of a phase-split LPTN with optimized parameters. The paper also includes a critical analysis of the optimized parameters, proposing a simplified, phase-split lumped-parameters thermal model suitable to predict the temperature variations in the different machine parts for PM synchronous electric machines used in BBW systems.

Study on the improvement design and ignition performance of B/KNO3 nitrate delay ignition charge under high overload

To solve the problems of increased delay time spread and weak ignition capacity in the case of B/KNO3 lead cable ignition charge structure under high overload conditions. Several improvement and optimization measures were taken. Such as increasing the pressure of B/KNO3 ignition powder, increasing the strengthening cap, reducing the particle size of boron powder and pressing the empty shell at the output end. The performance of the improved and optimized delayed ignition device was verified by the 23-tooth hammering test. Results showed that the delay time, delay precision and ignition capacity of the improved delay ignition device met the requirements under the condition of high overload.

Lignin intermediates lead to phenyl acid formation and microbial community shifts in meso- and thermophilic batch reactors

BackgroundLignin intermediates resulting from lignocellulose degradation have been suspected to hinder anaerobic mineralisation of organic materials to biogas. Phenyl acids like phenylacetate (PAA) are early detectable intermediates during anaerobic digestion (AD) of aromatic compounds. Studying the phenyl acid formation dynamics and concomitant microbial community shifts can help to understand the microbial interdependencies during AD of aromatic compounds and may be beneficial to counteract disturbances.ResultsThe length of the aliphatic side chain and chemical structure of the benzene side group(s) had an influence on the methanogenic system. PAA, phenylpropionate (PPA), and phenylbutyrate (PBA) accumulations showed that the respective lignin intermediate was degraded but that there were metabolic restrictions as the phenyl acids were not effectively processed. Metagenomic analyses confirmed that mesophilic genera like Fastidiosipila or Syntrophomonas and thermophilic genera like Lactobacillus, Bacillus, Geobacillus, and Tissierella are associated with phenyl acid formation. Acetoclastic methanogenesis was prevalent in mesophilic samples at low and medium overload conditions, whereas Methanoculleus spp. dominated at high overload conditions when methane production was restricted. In medium carbon load reactors under thermophilic conditions, syntrophic acetate oxidation (SAO)-induced hydrogenotrophic methanogenesis was the most important process despite the fact that acetoclastic methanogenesis would thermodynamically be more favourable. As acetoclastic methanogens were restricted at medium and high overload conditions, syntrophic acetate oxidising bacteria and their hydrogenotrophic partners could step in for acetate consumption.ConclusionsPAA, PPA, and PBA were early indicators for upcoming process failures. Acetoclastic methanogens were one of the first microorganisms to be impaired by aromatic compounds, and shifts to syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis occurred in thermophilic reactors. Previously assumed associations of specific meso- and thermophilic genera with anaerobic phenyl acid formation could be confirmed.

A Real-Time Estimation Method of Roll Angle and Angular Rate Based on Geomagnetic Information

In the course of the guidance transformation of the rotating projectile, the accurate acquisition of the roll angle and roll angle rate is very important to the attitude determination and guidance control of the rotating projectile. However, due to the impact of high rotation and high overload of projectile, MEMS gyros have problems such as limited range, saturation, overload, and even performance degradation, which make the roll angle rate unable to be output normally. At the same time, because the MEMS gyro estimation of roll angle is in the form of angular rate integral, the roll angle cannot be estimated normally if the roll angle rate cannot be accurately obtained. In order to solve this problem, a real-time estimation of projectile roll angle and roll rate based on geomagnetic information under high dynamic and high overload conditions is presented. Firstly, according to the motion characteristics of the rotating projectile, the motion model of the projectile is established, and the roll angle and roll angle rate of the projectile are estimated by Kalman filtering algorithm under the conditions of high axial rotation and high overload. Considering the high dynamic characteristics of the rotating projectile, based on the Kalman filter, the algorithm of the forgetting filter with the forgetting factor is further adopted to estimate the roll angle and roll angle rate, so as to reduce the error caused by the estimation delay in the process of high-speed dynamic change. Simulation data and semiphysical test results show that the accuracy of roll angle estimated by this method reaches about 2° in semiphysical test, which is one time higher than that calculated by the system. In the semiphysical experiment, the accuracy of the estimated roll rotation rate reaches 5 °/s, which is more than 6 times higher than that obtained by direct derivation. In the high dynamic stage, compared with the pure Kalman filter, the accuracy of roll angle with forgetting factor estimation is improved by an order of magnitude, and the accuracy of roll angle rate is improved by 4 times, which meets the desired accuracy of rotating projectile.

Temperature Field Calculation and Water-Cooling Structure Design of Coreless Permanent Magnet Synchronous Linear Motor

In this article, a water-cooled structure with water-cooled plates between the primary double-layer windings field of the primary structure under short-term high overload conditions and periodic operations is calculated. Second, the heat dissipation effects of two different waterway topologies are designed and compared. Based on the thermal network analysis model and multiphysical field coupling model, the heat dissipation effect of the water-cooled motor is obtained. In order to obtain the maximum sustainable working current that the motor can withstand under water-cooled conditions, a fast calculation model-response surface model-is established and the electromagnetic performance of the water-cooled motor is obtained. The analysis results show that the temperature rise of the water-cooled motor decreases greatly, and the average thrust increases by 2.73 times. Finally, the calculated and tested results of the prototype are compared and analyzed.

Experimental Research of Electrical Output Characteristics of Stacked PZT-5H Under High-Overload Conditions

Stacked piezoelectric ceramics (PZT-5H) are often used as sensors and pulsed power sources in moving objects. They will be subjected to a larger overload force when the moving objects collide with the target. In order to study the influence of the connection mode (parallel/series) of ceramic chips on the electrical output characteristics of stacked PZT-5H during overload, many experiments were performed using a nylon projectile to impact the stacked piezoelectric ceramic with different impact velocities by using a one-stage light gas gun as the loading device. The influence of a full bridge rectifier circuit on electrical output characteristics of the stacked PZT-5H was analyzed.

Design and bearing characteristics of planetary roller screws based on aerospace high-load conditions

Under the background of the rapid development of today’s aerospace industry, the bearing characteristics of planetary roller screw drive under high overload conditions are studied. Designing a high-load, high-performance precision planetary roller screw drive is of practical and significant. An axially spaced RV type planetary roller screw with a single nut is designed under aerospace conditions. Under the conditions of the aerospace working load and efficiency, the parameters and structures of the planetary roller screw are completed. Based on this, the bearing characteristics of the planetary roller screw are studied and the equivalent finite element model of the planetary roller screw is analyzed. Those analyses include stress and strain, elastic–plastic properties, transmission efficiency, and dynamic load capacity. The results show that the design of planetary roller screw meets the design requirements for aerospace conditions. And the results can provide a basis for the design and manufacture of planetary roller screws under high loads.

Numerical study of high-overload effect on liquid film of spray cooling

A two-dimensional numerical model was developed to study a heat and mass transfer process of liquid film formed by a row of droplets under high-overload conditions. The model was solved using the Volume of Fluid (VOF) method. Simulation cases were carried out with different droplets velocities and overload accelerations. The liquid film flow as well as no-phase-change heat transfer were studied during droplets hitting the flat surface. The simulation results obtained under high-overload and normal gravity conditions are compared to reveal the impact of acceleration on the heat and mass transfer performance. The analyses indicate that the average temperature of heated surface, Tsur, decreases with the increase of the droplet velocity under the normal gravity. While under horizontal high-overload conditions, Tsur decreases first and then increases with the increase of the droplet velocity. Tsur under horizontal high-overload is lower than the one under the normal gravity. When the droplet velocity is relatively high, the vertical overload acceleration has little influence on Tsur. However, when the droplet velocity is relatively low under vertical high-overload, weightless or overweight condition makes Tsur increase or decrease, respectively. The reason to cause this temperature change is that the shape of liquid film occurs different distortion phenomena in the high-overload conditions. High-overload inertia force plays an important role in the shape distortion of liquid film. The liquid film will be easy to pile up or break especially when the droplet velocity is relative low. This can cause adverse effect on the heat transfer process, such as local overheating. It will bring some harm on the cooling performance.

Simulation of Single Row of Droplets Impact on a Flat Surface Under High-overload Condition

A tow-dimensional model has been developed of a row of droplets impact on a flat surface heated with constant power. The simulation based on VOF (volume of fluid) method is carried out to simulate the liquid film flow with no-phase-change heat transfer during droplets hitting the flat surface. A series of case with different droplets velocities and overload acceleration are calculated. The results obtained under highoverload and normal gravity conditions are compared to show the effect of acceleration on the heat transfer performance.

Reservation-Based Scheduling for Automotive DSMS under High Overload Condition

Reservation-Based Scheduling for Automotive DSMS under High Overload Condition

A Proposed Method for the Determination of Current-Transformer Errors

CURRENT TRANSFORMERS for relay service must be able to function with reasonable accuracy under very high overload conditions, and it is therefore necessary that their accuracy for such high currents be verified. However, in performing the usual accuracy test at very high currents, certain difficulties are encountered — the principal ones being: