Composite Boxes Research Articles

Machine vision approach for monitoring and quantifying fish school migration

The precise monitoring and quantification of fish migration are crucial for enhancing agricultural productivity and promoting environmental conservation. However, conducting these tasks in natural environments presents challenges due to the subtle characteristics of fish and the inherent complexities in detection. This study addresses these challenges by introducing DVE-YOLO (Dynamic Vision Enhanced YOLO), a novel framework based on the YOLOv8 architecture, complemented by a tailored sample allocation strategy and a dedicated loss function. Operating on dual-frame input, DVE-YOLO integrates deep features from consecutive images to create composite anchor boxes from adjacent frames. This design enables DVE-YOLO to capture dynamic object features, reveal correlations of detected objects across frames, and facilitate efficient tracking and detection. Furthermore, this research proposes an innovative method for identifying fish migration through fish counting, documenting both the migration area and the duration of fish presence for subsequent analysis. Evaluation on an extensive fish migration dataset demonstrates that DVE-YOLO outperforms YOLOv8 and other mainstream detection algorithms, showcasing superior detection accuracy with higher AP50 and AP50−95 metrics. In terms of counting accuracy, DVE-YOLO achieves a lower Mean Squared Error (MSE) compared to YOLOv8+BoTSORT and YOLOv8+ByteTrack, indicating improved counting performance. Additionally, DVE-YOLO exhibits enhanced precision in identifying fish migration in contrast to YOLOv8+BoTSORT and YOLOv8+ByteTrack. Ultimately, these machine learning methods holds promising prospects for ecological applications.

Experimental study on the working mechanism and seismic performance of novel energy-dissipation boxes with different configurations

This paper presents a novel composite energy-dissipation beam-column joint that incorporates friction side plates (FSPs) and composite energy-dissipation boxes (EDBs). As replaceable components of this innovative joint, the composite EDBs significantly influence its overall seismic performance. To conduct a comprehensive study of the composite EDBs, eight specimens were fabricated, with parameters including filling material, construction gaps, and secondary loading. This investigation primarily examined the failure modes, hysteretic performance, strength degradation, stiffness degradation, and energy-dissipation capacity of the composite EDBs. The results indicated that increasing the construction gap can delay the buckling of dog-bone energy-dissipation plates (DB-EDPs), while secondary loading enhanced both the strength and stiffness of the specimens. Additionally, the filling material effectively restrained the out-of-plane buckling of the DB-EDPs, thereby improving the load-bearing capacity of the composite EDBs. The effectiveness of the filling materials was ranked as follows: wood > steel box > rubber. Finally, a theoretical load-bearing capacity formula for the specimens was derived, and the applicability was validated by comparing the experimental values with the theoretical predictions.

Buckling optimization of variable stiffness composite wing boxes with manufacturing defects

Buckling optimization of variable stiffness composite wing boxes with manufacturing defects

Hybridization effect on energy absorption capacity of composite crash boxes

AbstractCrash boxes are safety elements generally made of metallic materials and mounted on the chassis of vehicles to prevent possible injuries to driver and passengers by absorbing the energy generated during a collision and ensuring integrity of vehicle. In order to save fuel and reduce harmful gases released into the environment, the proportion of metallic materials used in vehicles is decreasing and being replaced by composite materials. While composite materials are as durable as metallic materials, they are preferred because they are lighter. In this study, circular composites consisting of glass (S1), aramid (S2), carbon (S3), and hybrid combinations of aramid‐carbon‐glass (S4), carbon‐glass‐aramid (S5), and glass‐aramid‐carbon (S6), all with epoxy resin matrices, were produced using the vacuum infusion method and investigated. Crush parameters, maximum peak loads and specific energy absorption of hybrid tubes with different fiber types and winding order were compared. S3 tube had the best energy absorption performance among all samples of 257.288 Joules, while the worst energy absorption performance was obtained for S2 tube with 30.944 Joules. Among the hybrid samples, the best result was determined as 166.50 Joule with hybrid S5. Although the energy absorption capacities of hybrid composite tubes were close to each other, they had lower results for energy absorption and specific energy absorption than S1 and S3. For specific energy absorption, as with energy absorption, the best result was obtained with S3, while the lowest result was obtained with S2.Highlights The aim of this study is to evaluate the performance of composite crash boxes. The effect of fiber type and hybridization was examined. Specific energy absorptions and maximum contact forces were compared. Cylindrical samples were produced by vacuum infusion. The variation of damage depending on fiber type was investigated.

Experimental and Numerical Investigation of Energy Absorption Characteristics of a E-Glass/Epoxy Crash Box

Crash boxes are energy absorbing components generally placed at the front end of cars to reduce the amount of damage at especially low impact velocities. The number of electric vehicles has been increasing recently, so weight reduction studies are. For this reason, lighter glass or carbon fiber reinforced composite crash boxes are preferred instead of steel ones. In the current study, the dynamic compression behavior of a rectangular cross-section thin-walled composite crash box was investigated both experimentally and numerically. The main aim of the study was to understand the effective damage modes and monitor the deformation sequence experimentally and numerically. Once the numerical model is verified then it can be further used to reveal the behavior at different impact velocities and geometries. The methodology followed in the study first started with the static mechanical characterization of the composite material. Within the scope of this study, 2×2 twill-woven glass fiber/epoxy crash boxes were produced using the vacuum bagging method. Quasi-static compression and tension tests were carried out in accordance with ASTM D3039 and ASTM D6641 standards. In the numerical part, Radioss finite element package was used with the material model of MAT 25 along with the failure option of Tsai-Wu. Experimental dynamic crushing tests of the crash box was carried out using a custom made drop-weight tester at impact velocity of 4.4 m/s and dropping mass with 450 kg. The material model constants were obtained once the coupon based static and dynamic tests were completed. From the dynamic crushing tests, maximum and mean force values of 225 and 65.0 kN were noted, respectively. There is close agreement between the experimental and numerical results both in terms of force and displacement values. This verified numerical model can further be used to investigate the crushing characteristics at different impact conditions.

Main characteristics of burial complexes of Central Kazakhstan in the Late Bronze Age

The main factual basis of the research comprised the materials of 25 necropoleis of the Late Bronze Age examined in the Karaganda and Ulytau regions of Central Kazakhstan. The total number of the investigated burials amounts to 167 individual structures. There were 190 burials recorded. Since the 2000s, nine cemeteries belonging to the Late Bronze Age have been investigated. There were 72 burial structures studied, including one of the eight largest mausoleums in the region — Karazhar-tas, excavated in 2016–2017. All known burial structures were divided into three groups: surface stone boxes, boxes imbedded in the bedrock, and ground graves, which, according to the characteristic above-ground structures, were divided into ten types of burial structures. It has been noted that for the first group of the burials, the most characteristic are quadrangular funeral structures erected using the masonry technique. The second group is dominated by quadrangular fences built from vertically set slabs, less often from stone laid on flat. The third group is clearly dominated by a ring-shaped layout in the form of the stones selected according to their dimensions, laid in a circle. The most numerous appeared to be the first group, for which the charac-teristic feature is the arrangement of the burial chambers in the form of stone boxes raised above the ground. The less repre-sentative was the second group with subsurface burials, including those that had a form of composite stone boxes. The third group comprised the burials in ground graves. It is assumed that in the first two groups, the westward orientation of the interred is predominant, with a certain role of the northeastern sector. The third group is characterised by the invariable orientation of the deceased in a southward direction with the sleeping position of the skeleton laid on the right side.

Response of trigger type to crash box energy absorption performance

In this study, carbon fiber reinforced polymer matrix composites were produced to investigate the trigger effect on energy absorption performance. Production was carried out by vacuum infusion method. Three types of trigger geometry were opened on the composite crash boxes produced and a comparison sample without trigger was prepared. The quasi-static compression tests of these four different samples were carried out and the energy absorption performances of the samples were evaluated with the obtained data. In addition, the damages of the samples were examined, and it was revealed how they changed with the trigger. Accordingly, the sample described as S-2, and the triggered sample, which consists of four symmetrical slits downwards from its upper surface, exhibited the best performance.

Buckling and post-buckling analysis of composite wing box under loads with torsion-bending coupling

In this paper, a mathematical model for the effect of different torsion-bending ratios on buckling and failure loads under complex operating conditions was proposed, and the buckling, post-buckling and failure behavior and mechanism of carbon fiber composite wing box were studied by combining experiments and simulations. A high-precision computational simulation model was established by considering detailed bolt arrangement information, as well as damage and failure of composite materials. The predicted buckling loads, failure loads, and damage modes are in good agreement with the experimental results. The results show that, under the condition of constant bending moment, as the torque increases, the linear strain of the box section remains consistent, while the shear strain increases significantly, leading to a change in the buckling mode and failure distribution. When the torsion-bending ratio is less than 2.0, the loading form of the structure is greatly affected by the torque. On the contrary, the buckling and failure loads are exponentially close to the pure torsional state. The mathematical model and simulation model in this study can provide an important reference for the structural design and failure mechanism analysis of large composite wing boxes.

Experimental and numerical investigation on the failure behavior of multi-spar composite box under bending and shear

Multi-spar composite boxes (MSCB) are common elements in structural design due to their high load capacity in different loading conditions. This paper presents an experimental and numerical investigation of the failure behavior of MSCB subjected to a combined bending-shearing load. Quadratic failure criteria and mixed-mode strain energy release rate criteria are used to predict the onset and propagation of damage at the inter-laminar interfaces of the MSCB, which was implemented into Abaqus/Explicit analysis via a user-defined material subroutine VUMT. At last, a good agreement between tests and numerical prediction was observed.

Experimental and numerical investigation on energy absorbing characteristics of empty and cellular filled composite crash boxes

Composite structures have been used in the automotive and aircraft industries because of their superior properties such as specific energy absorption ability, lightweight and crashworthiness. This paper aims to determine energy absorbing and deformation behaviours of composite crash boxes designed in different geometries by an innovative approach. The hand-layup vacuum bagging method was utilized to produce the composite crash boxes, which were developed with three different outer wall geometries (square, hexagon, and cylinder), and cellular filled square and hexagonal interiors. Carbon fibre reinforced polymer (CFRP) material was used in fabrication of the crash boxes. Experimental and numerical studies were conducted to investigate the energy absorbing and deformation behaviours under static compression load of the composite crash boxes. A commercial finite elements (FE) software (Ls-Dyna) was used for the numerical model. The study's findings revealed that cellular-filled composite crash boxes perform significantly better in terms of energy absorption performance. It was observed that filling an empty square type composite crash box with hexagonal cells increased the box's specific energy absorption capacity by around 140%.

Direct-spun CNT textiles for high-performance electromagnetic interference shielding in an ultra-wide bandwidth

Electromagnetic interference (EMI) generated by electronic devices is disruptive to surrounding electronic components and deemed harmful to human beings. As high-speed, miniaturized mobile devices become ubiquitous, developing lightweight, thin, and flexible electromagnetic shielding materials (ESMs) to replace the common metallic ones is of utmost importance. Here we report the development of a high-efficiency standalone ESM made of a self-standing CNT mat (CNTM). This textile is electrically conductive (∼50 × 103 S m−1) and can be post-treated by chemical oxidation or thin copper metalization, increasing the conductivity by ∼10 and ∼1000 times, respectively. CNTMs were tested for shielding effectiveness (SE) in an ultra-wide bandwidth of 30 kHz–70 GHz. Maximal SE of >120 dB was measured for a 30 g m−2 CNTM (<100 μm thickness) at 70 GHz. SE normalized by thickness (SE/t) reached a value of >20,000 dB cm−1 for an HCl-oxidized CNTM. Both SE values are the highest values for non-metal-based ESMs. The CNTMs' experimental EMI shielding behavior corresponds to Schelkunoff's theory which confirms that the CNTM SE is dominated by conductivity-dependent reflection at lower frequencies (<1 GHz) and thickness-dependent absorption at higher frequencies. CNTMs (20 g m−2) were utilized as EMI gaskets and in composite EMI enclosures, tested at 10–50 GHz and 50 MHz-90 GHz, respectively. EMI CNT gaskets reached an SE of 120.9 dB at 50 GHz, surpassing the performance of high-end commercial gaskets (600 g m−2). EMI composite boxes laminated with CNTMs reached an SE of 119.9 dB at 90 GHz, outperforming the non-CNT laminated reference.

An investigation on crashworthiness performance of adhesive bonding in automobile hybrid front bumper system subjected to high-speed impact

Adhesive bonding is widely used to join dissimilar materials and has proven its effectiveness so far. This study investigates the crashworthiness performances of the adhesive bonding in automobile hybrid front bumper system which connects the composite bumper beam and steel crash boxes by carrying out a series of numerical analyses. Initially, the ply thickness and orientation of the composite bumper beam were optimized to achieve impact properties as good as the steel bumper beam. Later, performances of three adhesives, namely, Araldite® AV138, 3M® DP8005, and Nagase Chemtex® XNR6852E-3 with stiff, ductile, and high toughness, respectively were evaluated for the proposed configuration of the hybrid front bumper system and the proper adhesive was selected correspondingly. Finally, optimization studies were performed for the top and the side adhesives in terms of the impact characteristics of the adhesives. The results of this study showed that it was possible to use the adhesive bonding to join dissimilar materials in the automobile hybrid front bumper system with the proper adhesive. Moreover, the crashworthiness performance of the hybrid front bumper system was highly affected from the design configurations of the adhesives. It was found that the optimum hybrid front bumper system (Case 1) exhibited peak crush force of 656 kN and absorbed 4.07 kJ energy. In addition, the top and side adhesives absorbed 0.073 and 0.13 kJ of energy, respectively, while 16.12% and 22.48% of the elements used in the top and side adhesives failed.

Development of efficient energy absorption components for crashworthiness applications: An experimental study

AbstractThis work experimentally investigates the quasi‐static crush response and energy absorption of glass‐reinforced epoxy thin‐walled crash box filled with nano‐aluminum oxide (Al2O3). The effect of the triggering (45 edge chamfering) and the weight percentage (wt%) of Al2O3 on the crushing performance have been studied. Field emission scanning electron microscope (FE‐SEM) and energy‐dispersive X‐ray spectroscopy (EDX) were adapted to show the elemental composition of the fabricated samples' surfaces. To follow the fracture mechanism, visual inspection, and scanning electron microscope (SEM) were performed. Two‐parameter Weibull distribution function was employed to statistically analyze the experimental results. Failure probability curves were established to help the designers in selecting the suitable material for energy‐absorbing applications. Results indicated that for untriggered glass/epoxy composite crash boxes, the inclusion of 1, 2, and 3 wt% of nano‐Al2O3 leads to an increase of, respectively, 16.34%, 48.46%, and 68.70% in the absorbed energy (U). While there is a decrease of 32.72% in (U) when adding 4 wt% of nano‐Al2O3. An enrichment of 9.00%, 18.04%, 31.53%, and 11.30% in crush force efficiency (CFE) was reached by the inclusion of, respectively, 1, 2, 3, and 4 wt% of nano‐Al2O3. Triggering has a considerable effect on the crashworthiness parameters of the fabricated composite crash boxes. A decrease of 6.56%, 10.11%, 4.01%, 4.76%, and 11.62% in the initial peak load (), an enrichment of 34.10%, 26.06%, 26.77%, 18.08%, and 28.97% in (CFE) and an improvement of 36.43%, 31.32%, 29.27%, 12.99%, and 52.47% in (U) were reported for composite crash boxes filled with 0, 1, 2, 3, and 4 wt% of nano‐Al2O3. It is obvious that glass/epoxy triggered composite crash boxes filled with 3 wt% of nano‐Al2O3 are appropriate to be used as energy absorbing device employed in vehicles due to their enhanced energy absorbing capabilities.

An experimental and numerical analysis on influence of triggering for composite automotive crash boxes under compressive impact loads

In automobiles there is large scope for composite materials to be used for manufacture of structural parts. The development of electric vehicles has caused for a gain in utilization of composites in automotive applications. In the event of a collision composites afford for an electrical insulation aimed at safety in contradiction of electric shock along with higher strength to weight ratios, which helps in making light weight automobile structures. But composite materials have peculiar as well as complex deformation patterns under compressive impact loading, which is common in vehicle collisions. The deformation pattern of the composites depends on the type of materials used for reinforcement as well as matrix and their layout. Triggers which are accommodated in the design of an element so that deformation initiates at the specific region and has a high impact on the attribute with reference to energy absorption the component as they modify the deformation modes. Therefore before using composite materials for structural parts in automobiles, it is essential to characterize their behaviour when subjected to impacts. For the parts under compressive impact loadings the common method employed for studying the behavior under such conditions is Drop weight impact testing. In this study a GFRP (glass fiber reinforced plastic) composites crash boxes with four different cross sections (square, cylindrical, hexagonal and decagonal) provided with two different triggering patterns (slot trigger and front end trigger) are subjected to drop weight impact testing. In this study, influence of triggering on composite crash box is investigated using experimental drop weight testing along with correlation of numerical simulation. The prime motive of this study is to illustrate the influence of triggers on the deformation pattern along with the force and energy absorption level for a GFRP crash boxes under drop weight axial impacts.

Influence of bat house design on hibernating bats - a case study in Herefordshire (UK)

In England, bats and their roosts are protected by national legislation. To permit development actions that would otherwise result in an offence relating to bats, it is first necessary to obtain a protected species mitigation licence containing protective measures. Due to the complexity of the topic, combined with the fact that monitoring is often limited, it can be difficult for practitioners to be certain of real conservation benefits of these measures. To build a new access road near Hereford (UK), a former artillery magazine (confirmed bat roost) building was demolished. Therefore, a legally binding English Nature/Natural England European Protected Species (EPS) Development Licence was obtained (2005). This licence stipulated mitigation and compensation measures to ensure the works could be carried out without harming bats and ensuring their favourable conservation status was maintained. Roost compensation measures were applied to two identical retained buildings. These included blocking doorways, provision of bat access grilles/internal roosting crevices, diverting downpipes inside, and installing straw matting (approx. 5cm deep, within one building only). The latter two measures were designed to increase internal humidity levels. Pre-compensation monitoring recorded two hibernating common pipistrelles in addition to lesser horseshoe and brown long-eared bat droppings. Post-compensation monitoring (2006-2016) recorded a minimum of three brown long-eared bats, three lesser horseshoe bats, one common pipistrelle and one barbastelle, suggesting the compensation methods may have increased both the numbers of species, and individual bats. These increases were small, hence not conclusive. Notably, during the post-compensation hibernation monitoring, brown long-eared bats were found in areas with lower humidity levels (48.6-78.8%) than lesser horseshoe bats (67.8-93.5%). The magazine containing straw matting had winter humidity levels approximately 20% higher than the other and supported a higher number of hibernating lesser horseshoe bats, but a lower number of hibernating brown long-eared bats. Within both buildings, all hibernating brown long-eared bats were found behind chipboard (approx. 70cm x 150cm) attached to wooden battens approx. 2cm from the internal walls rather than wooden or sawdust/ cement composite bat boxes.

Experimental study on the crashworthiness response of hybrid Al/GFRP crash-box structures under axial compression loading

In this research, the dynamic crushing behavior of crash boxes made of aluminum reinforced with Glass Fiber Reinforced Polymer (GFRP) with circular cross-section is presented. Energy absorption capacity and damage behavior for different composite wall thickness and fiber ply orientation were investigated. The result shows that adding composite layers to the aluminum column will improve the column’s energy absorption capacity. Nevertheless, the Specific Energy Absorption (SEA) of the aluminum structures generally higher than the hybrid systems. However, the hybrid column has higher crushing resistance than a combination of separate aluminum and composite crash boxes with the same geometry. This shows that interaction between aluminum and composites enhance the crash behavior since a stable and progressive crushing mode were observed, resulting in greater energy absorption. Additional research should be carried out to investigate further.

Drop-weight impact testing for the study of energy absorption in automobile crash boxes made of composite material

There is an ever-increasing demand in the automotive sector to continuously improve the performance and reduce cost through weight reduction in the structure of the vehicle. In the present scenario, it is also necessary to meet the standards set by crash safety regulating authorities in various parts of the world. In automobiles, the crash box is placed in the anterior region to absorb the impact energy in the event of an accident. Glass fiber reinforced plastic crash boxes have a high strength-to-weight ratio and also are good in energy absorption, particularly useful in this scenario. In this paper, the effectiveness of different triggers in combination with various geometries is investigated for Glass fiber reinforced plastic crash boxes using drop-weight impact testing. A trigger is a geometric irregularity introduced in the crash box design to alter the energy as well as force levels by modifying the deformation mode under loading. Comparison of change in force level, absorption of impact energy, specific energy absorption values was performed for composite crash boxes made of various types of cross-sectional geometries along with multiple patterns of triggers. Force versus displacement (F–D) curves are drawn for all the cases of the glass fiber reinforced plastic crash boxes to understand the behavior of each combination formed with various types of geometries and triggers, under impact loading. Strength-to-weight ratio was considered as the deciding factor for the comparisons to know the best and worst cases of the crash boxes made of different cross-sections along with various trigger types. This study provides detailed insights into the drop-weight impact testing procedure including the preparation of specimens, setting up the drop-weight impact test, preparation of specimen clamps, safety precautions involved, data acquisition from the test and its processing.

Assessment of CASL VERA for BWR analysis and application to accident tolerant SiC/SiC channel box

Application of the Virtual Environment for Reactor Applications (VERA) to BWR analysis is assessed in this paper by comparing results to those calculated using other widely-used modeling tools, namely the U.S. Nuclear Regulatory Commission’s PARCS/PATHS and the Serpent Monte Carlo particle transport code. Additionally, VERA is used to calculate 3-D temperature and fast neutron flux distributions in silicon carbide (SiC) fiber-reinforced, SiC matrix composite (SiC/SiC) BWR channel boxes, which are being studied as an Accident Tolerant Fuel core structural material concept. The code-to-code comparisons were favorable, and the SiC/SiC channel box evaluation demonstrates the many advanced modeling features VERA provides while also highlighting the non-uniformity in fast neutron flux distributions that can play a role in potential SiC/SiC channel box deformation. Traditional BWR analysis tools do not have the calculation fidelity necessary for coupled assessment of flux and temperature gradients in a SiC/SiC channel box. VERA is a state-of-the-art modeling environment that was developed to increase the safety and economic competitiveness of nuclear power through improved modeling accuracy. While VERA has already been deployed in the nuclear industry for PWR applications, the current study is a vital initial step in the extensive development, validation, and verification that VERA must go through to be useful for BWR applications.

Economical method for manufacturing of advanced light weight material crash box for automobiles

Manufacturing of composites is different from metals and requires special techniques. Therefore, this paper is dedicated to explaining in detail the manufacturing process for preparing the composite GFRP (glass fiber reinforced plastic) crash boxes. In this research paper, step by step procedure for manufacturing of the specimens is presented with details. The various steps involved in the manufacturing technique require design of moulds, estimation of curing time, techniques of curing and the methods of removal of the specimens from the moulds. Hand lay-up technique is used for making all the GFRP composite crash boxes in the present research paper. Manufacturing of mould for the specimen, precautions while dealing with glass fibers, hardening agents and resins. Wrapping techniques and curing time prediction, use of releasing agents for pull out of specimens are explained.

An Online Extrusion-compression Molding Method to Produce Wood Plastic Composite Packaging Boxes

Wood plastic composites are widely used to manufacture profiles by extrusion but rarely applied to make products by injection or compression for its poor flowability. Wood plastic composite packaging boxes were manufactured by both self-designed online extrusion-compression and traditional injection molding methods with different formula. The mechanical properties, buckling deformation, production capacity and final passed yield of packaging boxes and energy consumption was investigated with the two different methods. We find that the filling of bamboo fiber into polyolefins improves tensile strength but brings down impact strength in both processing method. However, for online extrusion-compression molding we can obtain a better tensile and impact strength. With the increase of bamboo fiber concentration and decrease of HDPE/PP mass ratio the buckling deformation declines, and a smaller buckling deformation can be obtained by the online extrusion-compression molding with respect to tradition injection molding. The comparison of energy consumption between the two processing methods reveals that it is a cost-effective way to manufacture wood plastic products, saving about 29.81% energy compared with traditional injection molding. Online extrusion-compression molding technique can be widely used to manufacture wood plastic composite products of irregular structure and large-format.