With transportation's rapid growth, ship-bridge collisions occur frequently, causing substantial losses. Ship-bridge anticollision facilities should not only protect the structural integrity of bridges but also minimise ship damage. This paper designs a novel ship-bridge anti-collision device based on a trapezoidal foam-filled composite sandwich structure. Using the finite element software LS-DYNA, a ship-anti-collision device-bridge collision model was established, taking into account pile-water-soil coupling. The study investigates the selection of box materials, filling materials and wall thickness for the novel anti-collision device. By analysing the damage characteristics of the ship, anti-collision device and pier under typical collision loads, the optimal material properties were determined. The impact resistance of the optimised device was evaluated under different ship speeds and collision angles, demonstrating that the novel anti-collision device exhibits excellent buffering and energy absorption, effectively reducing the peak collision force, extending the collision duration and reducing damage to the ship's bow structure.

Vessel collisions on bridge piers have become a potential threat to the safety of bridges crossing navigation waterways. Such collision will cause inevitable damage on bridge piers and hence reduce the performance of the whole structure. It is therefore critical to identify the condition of abridge pier after a vessel collision event to judge whether it can still be used or certain rehabilitation is required to recover its normal operation. This paper develops an intelligent approach based on machine learning algorithms to identify the evolution process of damage on abridge pier during collision using sensor-measured acceleration time-history data considering the effects of multi-hazards. A barge vessel is employed and atypical reinforced concrete (RC) bridge pier is considered in this study. A coupled vessel-pier collision model (CVCM) considering soil-pile interactions and material non-linearity of RC components is developed and employed to generate pseudo-experimental data to assess the accuracy of the proposed damage identification strategy. The results demonstrate the potential of the proposed strategy for intelligent damage identification of waterway-crossing bridge piers after vessel collision.

This study investigates the collision model of cassava seed stems in precision planters. Utilizing a physical property analyzer and a custom test platform based on collision dynamics principles, we measured and analyzed the forces and recovery coefficients of seed stem collisions. Mixed orthogonal and one-way tests were conducted to identify the main factors affecting the collision recovery coefficient of seed stems, including collision contact material, drop height, seed stem mass, moisture content, drop direction, and seed stem variety. The results from the orthogonal tests indicated that the factors influencing the collision recovery coefficient were ranked as follows: collision contact material > drop height > seed stem mass > moisture content > drop direction > seed stem variety. Notably, the effects of impact contact material, drop height, stem mass, and moisture content were significant, while the effects of drop direction and seed stem variety were relatively insignificant. The one-way test results revealed that the collision recovery coefficients for cassava seed stems with structural steel Q235, rubber sheet, seed stems, and sandy loam soil decreased progressively, with values for SC205 being 0.8172, 0.6975, 0.6649, and 0.6341, respectively, and values for GR4 being 0.7796, 0.7132, 0.6913, and 0.6134, respectively. Furthermore, as drop height increased, the collision recovery coefficient of cassava seed stems decreased; similarly, higher stem mass and moisture content correlated with lower coefficients. To minimize impact during critical stages of cassava planting, transportation, and processing, materials with lower recovery coefficients should be prioritized in equipment design. Incorporating rubber coatings can effectively mitigate collision effects in components such as seed supply and planting mechanisms. These findings provide valuable insights for designing and enhancing key mechanical features in machinery used for planting, transporting, and processing cassava.

This paper presents a novel and efficient method for generating three-dimensional (3D) mesoscale structures of concrete using the discrete element method (DEM). The proposed approach enables the flexible and precise simulation of various aggregate shapes and volume fractions, which is crucial for sensitivity analysis and computational studies. Unlike traditional digitalization methods, this technique focuses on creating adjustable synthetic models to investigate the impact of different parameters on the mechanical properties of concrete. This technique demonstrates significant advantages in generating complex concave aggregates and high aggregate volume fraction models while allowing for flexible control of particle spacing, thus enhancing computational efficiency and model accuracy. Numerical simulations using the proposed method show excellent agreement with laboratory experimental results, validating its reliability. This method not only facilitates deeper sensitivity analysis but also aids in optimizing concrete designs and applications by providing insights into the effects of various parameters on concrete performance.

Facing the challenges of in-situ utilization of lunar regolith resources, applying an external electric field to manipulate lunar particles has become a promising method for space particle control, which mainly depends on the particle charging properties in the applied electric field. Using the surficial lunar regolith samples brought back from the Moon by the Chang'e-5 mission (CE5 LS), this work successively studied their charging properties, particle dynamics, and their collision damages to aerospace materials under the action of an external electric field in high-vacuum conditions. The results indicated that the charging process and electrostatic projection of lunar regolith particles under high-vacuum conditions were different from those under atmosphere conditions. The particle diameter range of CE5 LS used in the experiment is 27.7-139.0 lm. For electric field strength of 3-12 kV cm-1, the charge obtained by CE5 LS is 4.8 x 10-15- 4.7 x 10-13 C and the charge-to-mass ratio is 1.2 x 10-5-6.8 x 10-4 C kg-1. The CE5 LS is easier to be negatively charged in an external electric field. Furthermore, significant damages were observed on the target impact surfaces, indicating severe influences of lunar regolith particles on aerospace materials. Our work contributes to a more comprehensive understanding of physical mechanisms controlling the lunar regolith shielding and utilization, and will inspire broad efforts to develop the lunar in-situ engineering solutions. (c) 2024 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

To investigate the influencing factors and intrinsic relationships between potato impact force and impact damage during potato soil separation, a testing system for potato impact force was established. The impact force test system is composed of a base, a height adjustment device, a simple separation screen, a soil storage tank, an impact force sensor, and so on. By allowing potatoes to fall freely to simulate the collision process, impact force data are collected, and a high-speed camera is used to locate the impact position and analyze the degree of damage. Through the response surface analysis method, the influencing factors and laws of the impact force and impact damage during the collision process between potatoes and rods under soil and no-soil conditions were studied. The results of the response surface analysis indicate that when the screen inclination is within the range of 14.12 degrees to 14.77 degrees, falling height ranges from 453.83 mm to 500 mm, screen rod spacing falls within 36.50 mm to 40 mm, and the screen rod material is rubber. Potatoes can still be at a relatively low damage level when enduring a large impact force. This study has significant implications for reducing potato impact damage during harvesting, enhancing economic benefits in the potato industry, and advancing the technical level of potato harvesting equipment. In the future, based on the results of this study, further exploration can be made to optimize the design of potato harvesting equipment so as to better reduce the damage to potatoes during harvesting and subsequent processing processes and promote the sustainable development of the potato industry.

Vessel collisions pose significant threats on the safety of cross-channel bridges. Previous studies have paid little attention on the impact performance of common arch bridges with gravity foundations in inland waterways. This study aims to comprehensively investigate the anti-impact resistance and analyze the damage and failure mechanisms of arch bridges under vessel collisions. The entire process of vessel-bridge collision is simulated using three-dimensional explicit finite element technique. The damage characteristics, as well as the progressive collapse process of arch bridge are investigated thoroughly. Moreover, the rational calculation method for bridge lateral resistance against vessel collisions (BRaVC) is discussed. The results show that the gravity foundation bottom of arch bridge can be fixed in vessel-bridge collision numerical analysis due to insignificant foundation-soil interaction. The head-on barge collision on the bridge pier leads to indistinctive lateral displacement, while obvious local damage can be observed. The impact displacement of the bridge pier is not positively correlated with the impact energy according to the impact load spectra analysis. Barge collision on the main arch results in the progressive collapse of the bridge due to unbalanced horizontal thrust from the arch on the other side. The rational BRaVC can be calculated by using sectional strength based on elastoplastic analysis.

A series of numerical simulations were completed to investigate the behavior of intact, fire -damaged, and Carbon Fiber -Reinforced Polymers (CFRP) retrofitted reinforced concrete (RC) bridge columns of varying sizes subjected to vehicle collisions. Three-dimensional finite element models of isolated RC columns and their foundation systems surrounded by soil volumes were developed using LS-DYNA. A comprehensive parametric study was carried out to investigate the effects of nine demand and design parameters on the performance of bridge columns. Studied parameters included: column diameter, column height, unconfined compressive strength, steel reinforcement ratio, fire duration, CFRP wrap thickness, wrapping configuration, vehicle 's mass, and vehicle 's speed. For each studied scenario, Peak Twenty-five Milli -second Moving Average ( PTMSA ) was employed to estimate the Equivalent Static Force ( ESF ) corresponding to each vehicle collision scenario. Resulting ESF s were then utilized to assess effectiveness of the current ESF approach available in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design ( AASHTO-LRFD ) Bridge Design Specification for analyzing and helping design bridge columns under vehicle collision. Multivariate nonlinear regression analyses were used to derive an empirically based, simplified equation to predict the ESF that corresponds to a vehicle collision. Rather than constant design force, this equation established a correlation between ESF and kinetic energy, column axial capacity, and column height. Results indicated that the proposed equation is reliable and can accurately predict ESF s over a diverse range of collision scenarios that included intact, fire damaged, and CFRP retrofitted columns. To facilitate realistic implementation of the derived equation, an ESF assessment framework was also devised.

The design of a good ship fender is important for protecting vessels or offshore structures during ship collisions or berthing, which could result in severe and costly damages. Sandwich fenders are widely used in the design of vessel fenders; however, little is known of how the order of arrangement of the sandwich material layers can affect sandwich fender performance. In addition, this paper investigates whether naturally occurring sand (soil) material along the riverbank in canals can be regarded as a good fender. Finite element analysis using an ANSYS Autodyn numerical solver showed that sand is a good fender, and generally, a fender sandwich having a hard material layer in the middle and soft materials placed at both sides is better at protecting fended structure and vessels made of different materials than any other arrangements. The overall result was validated using a simplified analytical method and LS-DYNA, and there is considerable result consistency.

To provide foundational data for parameter design and performance analysis of high-performance processing equipment, the collision model between jujube-parts and the parameter effects on coefficient of restitution (COR) were investigated. Jujube samples from the sandy lands of southern Xinjiang during the harvest season were utilized, with experimental factors including collision angle, falling height, collision material, moisture content, and collision parts. Single-factor tests and mixed orthogonal tests were conducted to explore the impact of parameter on COR. Utilizing the specular reflection principle, a 3D impact analysis of jujube was performed, and a kinematic model of the falling and impact process was established to determine the COR. Results indicate that the COR of Jun (Zizyphus jujuba cv. Junzao) is higher than that of Hui (Zizyphus jujuba cv. Huizao), and the ventral part exhibits a higher COR compared to the other four parts. Collisions with steel yield higher COR values compared to soil. Furthermore, for collisions with steel material, both Jun and Hui exhibit a decrease in COR with increasing falling height and moisture content, while the COR increases with an increase in collision angle. The influencing factors on COR follow the order of collision material > variety > moisture content > collision angle > falling height > collision part. These findings offer valuable insights for jujube processing research and for preventing mechanical damage to jujube fruits.