Maximum Deformation Research Articles

Failure analysis of atmospheric relief diaphragm in the low pressure steam turbine

In this study, the causes of failure and prevention methods for the atmospheric relief diaphragm in a low-pressure steam turbine were evaluated. The atmospheric relief diaphragm is designed to vent and burst at its center when the pressure in the exhaust housing exceeds 0.7 barG due to steam. However, visual inspection revealed that failure occurred along the flange mounting, rather than at the center of the diaphragm. Fatigue failure was identified as the cause, based on SEM analysis. Internal pressure fluctuations in the turbine caused bending along the fixed edge of the diaphragm. To confirm the occurrence of fatigue failure, finite element analysis was performed using a maximum internal pressure of 0.023 barG and a frequency of 60 Hz. The maximum deformation was 18.8 mm, which is less than the distance between the diaphragm and the knife, 30 mm. However, the maximum stress was 23.7 MPa, which exceeded the fatigue strength of A1050, 15 MPa, with stress concentration at the diaphragm edge, confirming edge fatigue failure prior to central knife failure. To identify an alternative material, finite element analysis was conducted using higher fatigue strength than A1050 under the same conditions. While the maximum stress was similar to that of A1050, it was below the fatigue strength of the alternative materials. Consequently, to prevent unexpected failures, it is recommended to use materials with higher fatigue strength than A1050 to enhance fatigue life of the diaphragm.

Analysis on dynamic characteristics of dam material and seismic response of embankment dam in Longyang Reservoir

PurposeThe geological conditions of Longyang Reservoir are complex and it is located in strong earthquake area. In order to determine its seismic characteristics, the seismic response and residual deformation of embankment dam should be studied to provide calculation basis for dam design and construction.Design/methodology/approachBased on the geological survey data of Longyang Reservoir, the dam filling materials are tested by dynamic deformation tests, and the equivalent linear constitutive model parameters of the filling materials are obtained. Based on Duncan-Chang E-B model, the stress state of embankment dam in Longyang Reservoir before earthquake is calculated, and the dynamic response and earthquake residual deformation of embankment dam in Longyang Reservoir under earthquake condition are calculated by using equivalent linear model and Shen Zhu-jiang’s residual deformation model.FindingsThe results show that with the increase of dynamic shear strain, the dynamic shear modulus decreases and the damping ratio increases. The scatter plot between dynamic shear modulus and dynamic shear strain, and the scatter plot between damping ratio and dynamic shear strain under different confining pressures show strips. The calculation results shows that the acceleration of embankment dam in Longyang Reservoir increases with the increase of dam height, and the acceleration distribution has obvious amplification effect. Combined with the maximum dynamic shear strain during the earthquake and the state before the earthquake, the maximum vertical residual deformation of embankment dam in Longyang Reservoir is 2.98 cm which occurs at the top of the dam, calculated by the Shen Zhu-jiang’s residual deformation model.Originality/value Finite element calculation model parameters of embankment dam are obtained by dynamic triaxial tests. Seismic dynamic responses and residual deformation of embankment dam are analyzed. With the increase of dam height, the acceleration distribution shows an obvious amplification effect. The vertical displacement of embankment dam is larger along the dam axis and decreases in the upstream and downstream direction. The maximum horizontal displacement of embankment dam occurs in the middle of upstream and downstream dam slopes.Highlights(1)Finite element calculation model parameters of embankment dam are obtained by dynamic triaxial tests.(2)Seismic dynamic responses and residual deformation of embankment dam are analyzed.(3)With the increase of dam height, the acceleration distribution shows an obvious amplification effect.(4)The vertical displacement of embankment dam is larger along the dam axis and decreases in the upstream and downstream direction.(5)The maximum horizontal displacement of embankment dam occurs in the middle of upstream and downstream dam slopes.

Fluid-Solid coupling analysis of PTFE impeller in hydraulic turbines for sewage resource utilization

Abstract Hydraulic turbines, vital energy-saving devices, convert pressure energy from liquid fluids into mechanical energy. As wastewater resource utilization and zero discharge industries proliferate, relevant research is of great interest. In order to design a suitable medium and low pressure hydraulic turbine for industrial water treatment, we conducted a study analyzing the stress and strain characteristics of a PTFE turbine impeller by means of bi-directional fluid-structure coupling numerical simulation. Our findings suggest that the impeller’s maximum equivalent stress and maximum deformation fall within acceptable material limits, with stress concentration at the blade-cover plate interface. The blade experiences maximum deformation at its midpoint due to high liquid pressure on the volute periphery. Fluid solid coupling reduces the maximum equivalent stress of the impeller by about 1.65MPa and the maximum deformation of the blade by about 0.05mm. The equivalent stress at the sampling point fluctuates periodically, with a significant change in stress amplitude at the sampling point of the cover plate on one side of the support surface, increasing susceptibility to fatigue damage.

Stability analysis of deep foundation pit with a double-row cast-in-place piles and diagonal steel lattice braces under sloped excavation conditions

Existing deep foundation pit support structures are commonly composed of external earth-retaining structures, internal horizontal bracings, and vertical columns. A closed bracing system, often formed by a horizontal support through a bracket board, frequently impedes vertical excavation and soil removal operations in the foundation pit, and the processes of assembly and dismantling are complex and time-consuming. This study presents a combined support system and construction method consisting of cast-in-place piles and diagonal steel lattice braces. For sloped excavation, diagonal braces were constructed by slotting through the reserved soil, allowing the use of a single layer of support within the excavation depth. This approach significantly optimizes the construction process, reducing both project duration and overall cost. The field monitoring results indicated that the support method effectively controlled the lateral displacement of the pile bodies. Field monitoring results demonstrated that the proposed support system effectively controlled the lateral displacement of the pile bodies. The adoption of a support-first, excavation-second approach significantly controlled the settlement of the ground surface around the foundation pit, thereby preventing excessive increments in the axial force of the supports due to the large longitudinal depth excavation. The calculation results of the three-dimensional finite element model for foundation pit excavation and support indicate that the proposed support method results in a decreasing ratio of the maximum lateral deformation depth of the pile body, denoted as δh-m, to the excavation depth He as the excavation depth increases. This implied that the displacement of the pile body was strictly controlled. When the depth of the foundation pit excavation exceeded 10 m, the maximum lateral deformation occurred below 10 m along the pile shaft. The diagonal steel lattice braces transferred the load to the top of the cast-in-place piles at the bottom of the pit, where the stress concentration occurred. During construction, special attention must be paid to the strength of the connection between the pile top and the connecting beams.

Design, fabrication, and characterization of a deformation-restricted piezoelectric vibration energy harvester triggered by a stopper

Vibration energy harvesting based on piezoelectric effect is emerging as a promising sustainable energy solution for micro-electromechanical systems and wireless sensor networks. Whereas, reliability issues stemming from excessive deformation-induced damage to piezoelectric materials have hindered the progress of piezoelectric vibration energy harvester development. Herein, an indirect triggering method involving a stopper has been implemented to design the deformation-restricted piezoelectric vibration energy harvester (D-RPVEH). This device utilizes the stopper to limit the maximum deformation of the piezoelectric beam, facilitating unidirectional deformation. Consequently, the D-RPVEH delivers enhanced reliability even under unexpected excessive impacts. The feasibility of the proposed principle and design are proved by finite element simulation and experimental test. Most importantly, the research results are found that the simulated end displacement and experimental voltage of PZT beam declined with the decrease of stopper height difference. Moreover, the efficacy of limiting the piezoelectric beam's maximum deformation by implementing the stopper structure is supported by both simulation and experimental findings. The D-RPVEH device can achieve a peak power output of 2.58 mW at frequencies as low as 5.5 Hz, utilizing an optimal load resistance of 30 kΩ. Furthermore, it can illuminate a minimum of 60 blue commercial LEDs connected in series. Therefore, the D-RPVEH not only has good power generation performance but also has high reliability. This design will provide a reference for the research on improving the reliability of PVEH.

Improved black-winged kite algorithm and finite element analysis for robot parallel gripper design

This paper presents a comprehensive study on the design optimization of a robotic gripper, focusing on both the gripper modeling and the optimization of its parallel mechanism structure. This study integrates the Black-winged Kite Algorithm (BKA), Finite Element Analysis (FEA), Backpropagation Neural Network (BPNN), and response surface optimization techniques. The Good Point Set (GPS), nonlinear convergence factor, and adaptive t-distribution method improve BKA, which enhances exploration and exploitation performance, convergence speed, and solution quality. Subsequently, the parallel mechanism structure is designed to minimize the total mass, total deformation, and maximum equivalent stress. The central composite design (CCD) method was used to design the FEA experiment and establish the BKA-BPNN regression prediction model. The RMSE of this model’s training set and test set are 0.001615 and 0.0029328. A response surface optimization model is constructed to determine the best design solution. The optimized design achieves a 33.12% reduction in maximum equivalent stress, a 1.47% decrease in total mass, and a 0.16% reduction in maximum total deformation. This study provides valuable insights into the design optimization process for robotic grippers, showcasing the effectiveness of the proposed methodologies in enhancing performance while reducing mass and improving structural integrity.

Simulation analysis and optimization of pilot type electro-hydraulic proportional directional valve based on multi field coupling

The pilot-operated electro-hydraulic proportional directional valve is widely used in complex and precision engineering fields. Its operational stability and reliability determine the overall performance of the hydraulic system. During the working process of the pilot-operated electro-hydraulic proportional directional valve, the spool is deformed due to the influence of pressure and temperature, resulting in problems such as clamping or stagnation. In order to solve this problem, this study uses the fluid-solid-thermal coupling simulation method to analyze the flow field characteristics and thermal deformation of the spool with different structural throttling grooves, and optimizes the U-shaped throttling groove structure. The results indicate that as the valve opening increases, the front section of the throttling groove becomes the primary region where the maximum radial deformation of the spool occurs. In this paper, the steady-state flow force of the valve core is taken as the measurement standard, the constraint range of the structural parameters is determined, and the radial thermal deformation is included in the optimization analysis of the structural size. It’s verified that the optimized flow characteristics are improved by about 32 % compared with that before optimization, and the maximum steady-state flow force after considering thermal deformation is reduced by about 4N compared with that before optimization. This provides an important design basis and reference for the structural design and optimization of the pilot electro-hydraulic proportional directional valve.

Performance evaluation of a novel adaptive temperature-controlled lining technology based on thermo-hydro-mechanical coupling analysis

To mitigate the hazards of high geotemperatures in hydraulic tunnels, the performance of a novel adaptive temperature-controlled lining was investigated across various working phases of high geothermal tunnels using the thermo-hydro-mechanical coupling analysis with the finite element software COMSOL. The results indicated an error margin of only 2% to 6% compared to the field measurements, proving the feasibility of the method. Compared with the conventional concrete lining, the adaptive temperature-controlled lining reduced the average inner wall temperature by approximately 55% during construction, decreased the maximum thermal deformation by approximately 37%, transferred the localized energy elevation from the inner wall to the outer lining, and lowered the maximum elastic strain energy density by approximately 62%. During the water-filled operational phase, the radius of temperature influence in the low-temperature zone of the adaptive temperature-controlled lining expanded by approximately 20%, whereas the maximum thermal stress decreased by approximately 76%, the thermal deformation by 50%, and the elastic strain energy density by 88%. Throughout both the construction and operational phases, the adaptive temperature-controlled lining significantly enhanced the temperature control, improved the stress distribution, and reduced the risk of concrete cracking. These findings could offer the innovative engineering insights into the design, construction, and operation of high-geothermal tunnels.

Research on the evolution law and control technology of deviatoric stress in the surrounding rock of gob-side entry retaining

Gob-side entry retaining (GER) play a crucial role in enhancing coal recovery, improving roadway stress conditions, and ensuring safe and efficient mining operations. This study focuses on investigating the stability characteristics of surrounding rock using flexible formwork concrete (FFC) along the headgate of 3405 panel. According to the fracture pattern of roof, a mechanical model of GER was developed. This study derived expressions for the support resistance of the filling body and determined its optimal bearing capacity. A FLAC3D numerical model was employed to simulate the GER process, segmented into early, middle, and late stages. Simulation results demonstrate a progression in peak deviatoric stress and extent of plastic zones in the surrounding rock. This evolution includes an initial minor increase (early stage), followed by rapid escalation (middle stage), and eventual stabilization (late stage). The middle stage emerges as critical, characterized by pronounced mining-induced stress effects on the roof. During this phase, significant changes are observed in deviatoric stress curves, with plastic zones rapidly migrating deeper into the rock mass. Practical implementation of the findings revealed a maximum deformation of the filling body of only 198 mm, affirming the feasibility of employing FFC in GER. This research provides valuable insights into managing stability concerns in GER thereby enhancing safety and operational efficiency in coal mining under similar conditions.

Modular design and structural optimization of CubeSat separation mechanism

In order to achieve the design requirements of light weight and high stiffness of the CubeSat modular separation mechanism, a BPNN-GA-PSO size optimization method is proposed to optimize the design of the separation mechanism. Firstly, the separation mechanism of modularization and standardization is analyzed to select the optimization objects. Then, a hierarchical optimization strategy of topology optimization followed by size optimization is adopted to find the global optimum using a hybrid GA-PSO optimization algorithm. Meanwhile, the BPNN surrogate model is introduced to improve the optimization efficiency. The results show that the mass proportion of the optimized separation mechanism is reduced to 18 %, and the maximum deformation of the separation mechanism is 0.123 mm, which meets the design requirements of light weight and high stiffness of the separation mechanism. It proves the applicability of the optimization method to the optimal design of the separation mechanism. The CubeSat modular separation mechanism designed in this paper has been verified by ground verification with overload, vibration, and shock mechanical tests, and successfully deployed the BY-03 satellite in-orbit, which can provide reference for the design and development of subsequent CubeSat modular separation mechanisms.

Experimental and Numerical Insights into the Multi-Impact Response of Cork Agglomerates

Due to their extraordinary qualities, including fire resistance, excellent crashworthiness, low thermal conductivity, permeability, non-toxicity, and reduced density, cellular materials have found extensive use in various engineering applications. This study uses a finite element analysis (FEA) to model the dynamic compressive behaviour of agglomerated cork to ascertain how its material density and stress relaxation behaviour are related. Adding the Mullins effect into the constitutive modelling of impact tests, its rebound phase and subsequent second impact were further examined and simulated. Quasi-static and dynamic compression tests were used to evaluate the mechanical properties of three distinct agglomerated cork composite samples to feed the numerical model. According to the results, agglomerated cork has a significant capacity for elastic rebound, especially under dynamic strain rates, with minimal permanent deformation. For instance, the minimum value of its bounce-back energy is 11.8% of the initial kinetic energy, and its maximum permanent plastic deformation is less than 10%. The material’s model simulation adequately depicts the agglomerated cork’s response to initial and follow-up impacts by accurately reproducing the material’s dynamic compressive behaviour. In terms of innovation, this work stands out since it tackles the rebounding phenomena, which was not previously investigated in this group’s prior publication, either numerically or experimentally. Thus, this group has expanded the research on cork materials’ attributes.

Formation of property gradient in coarse-grained niobium using a wedge tool: Experiment and analysis

We introduce a novel severe plastic deformation process for coarse-grained niobium, which employs a tool with an inclined (wedge) surface for deforming the material by a reverse shear scheme. The process increases the intensity of shear deformations and the depth of plastic deformation in the body of the workpiece when a wedge tool acts on its surface. The essence of the process is in the repeated displacement of the workpiece material in opposite directions during the asymmetrical introduction of a wedge tool until the required degree of deformation is accumulated in the tool-affected volume. This deformation scheme applies a 15° angle wedge tool to a 21-mm high workpiece. After nine cycles of plastic deformation, a gradient of the accumulated degree of deformation in the range of true strain e = 0.3–4.5 was created. At maximum deformation, the microhardness of the workpieces increased by 1.86 times and the tensile strength by 1.6 times. Fractograms show a significant influence of the accumulated degree of deformation on the nature of the fracture. The finite element method simulation of the deformation process showed that creating a uniformly strengthened layer requires at least five deforming operations. For example, the proposed reverse shear process with a wedge tool can be applied to improve the structure of the surface layers of niobium ingots for subsequent forming. Due to the creation of a significant gradient of properties, the reverse shear process can be used as an express method for determining the mechanical characteristics of different materials in a wide range of accumulated degree of deformation.

Hydrodynamic Characteristics of Preloading Spiral Case and Concrete in Turbine Mode with Emphasis on Preloading Clearance

A pump-turbine may generate high-amplitude hydraulic excitations during operation, wherein the flow-induced response of the spiral case and concrete is a key factor affecting the stable and safe operation of the unit. The preloading spiral case can enhance the combined bearing capacity of the entire structure, yet there is still limited research on the impact of the preloading pressure on the hydrodynamic response. In this study, the pressure fluctuation characteristics and dynamic behaviors of preloading a steel spiral case and concrete under different preloading pressures at rated operating conditions are analyzed based on fluid–structure interaction theory and contact model. The results show that the dominant frequency of pressure fluctuations in the spiral case is 15 fn, which is influenced by the rotor–stator interaction with a runner rotation of short and long blades. Under preloading pressures of 0.5, 0.7, and 1 times the maximum static head, higher preloading pressures reduce the contact regions, leading to uneven deformation and stress distributions with a near-positive linear correlation. The maximum deformation of the PSSC can reach 2.6 mm, and the stress is within the allowable range. The preloading pressure has little effect on the dominant frequency of the dynamic behaviors in the spiral case (15 fn), but both the maximum and amplitudes of deformation and stress increase with higher preloading pressure. The high-amplitude regions of deformation and stress along the axial direction are located near the nose vane, with maximum values of 0.003 mm and 0.082 MPa, respectively. The contact of concrete is at risk of stress concentrations and cracking under high preloading pressure. The results can provide references for optimizing the structural design and the selection of preloading pressure, which improves operation reliability.

Dynamic Characteristics of the Long Runout Rock‐ice Avalanche at High Altitude—A Case from the Zelongnong Basin, Eastern Himalayan Syntaxis, China

AbstractRock‐ice avalanches have frequently occurred in the Eastern Himalayan Syntaxis region due to climate change and active tectonic movements. These events commonly trigger catastrophic geohazard chains, including debris flows, river blockages, and floods. This study focuses on the Zelongnong Basin, analyzing the geomorphic and dynamic characteristics of high‐altitude disasters. The basin exhibits typical vertical zonation, with disaster sources initiating at elevations exceeding 4000 m and runout distances reaching up to 10 km. The disaster chain movement involves complex dynamic effects, including impact disintegration, soil‐rock mixture arching, dynamic erosion, and debris deposition, enhancing understanding of the flow behavior and dynamic characteristics of rock‐ice avalanches. The presence of ice significantly increases mobility due to lubrication and frictional melting. In the disaster event of September 10, 2020, the maximum flow velocity and thickness reached 40 m/s and 43 m, respectively. Furthermore, continuous deformation of the Zelongnong glacier moraine was observed, with maximum cumulative deformations of 44.68 m in the distance direction and 25.96 m in the azimuth direction from March 25, 2022, to August 25, 2022. In the future, the risk of rock‐ice avalanches in the Eastern Himalayan Syntaxis region will remain extremely high, necessitating a focus on early warning and risk mitigation strategies for such basin disasters.

Integrated framework of multi−physics mechanism models for gas−powder flow, molten pool evolution and part deformation in high alloy steel additive manufacturing process

Multi−physics numerical models for metal additive manufacturing (MAM) could replace the expensive trial−and−error experiments, reveal the mechanisms of printing process, and provide an effective means of optimizing process parameters and mitigating part defects. However, the existing simulations of MAM process seldom consider the coupling effects between multiple recursive processes. There is an urgent need to overcome the dilemma of limiting MAM process simulation to a localized single sub−process. For directed energy deposition (DED) additive manufacturing process, the integrated simulation framework proposed in this study consists of a gas−powder flow model, a heat and fluid flow model, and a sequentially coupled thermal–mechanical model, which can be used to predict the feedstock feeding process, the evolution of molten pool, and the residual deformations of metal part, respectively. The accurate results of the three recursive sub−processes can be obtained by delivering the validated parameters between models. Corresponding experiments are conducted to verify the accuracy of the integrated framework based on 12CrNi2 alloy powders. The deviation of the predicted focal distance of powder streams is 5.14 %, and the deviations of the predicted molten pool height and width are all less than 8.5 %. The integrated framework could rapidly and accurately predict the residual deformation tendency and the position where the maximum deformation occurs. For single−track and eight−layer line deposition, the deviations of the predicted maximum deformation are all within 0.1 mm. The integrated framework could efficiently provide accurate and comprehensive solutions for optimizing DED process.

The study of design and optimisation for CFRP combined pier anti-collision device

A CFRP honeycomb combination anti-collision device with a larger anti-collision level, greater crashworthiness, and longer service life was designed to safeguard the ship and piers in the event of an unintentional collision. Taking large-tonnage cargo ships and common bridge piers in the middle reaches of the Yangtze River as the research objects, the energy conversion response, impact force response and impact depth response of the collision were studied considering the collision conditions between the ship and the bare pier and the collision avoidance device. On this basis, the response surface method, variance analysis method and efficacy coefficient method were further used to take the shell thickness of the collision avoidance device and the thickness of the internal steel structure as the design parameters. The multi-objective optimisation design of the CFRP composite anti-collision device is carried out by selecting the ship impact force, the total internal energy absorbed by the anti-collision device, the total mass, and the inner diameter of the honeycomb steel structure as the optimisation objectives. The results show that the impact force reduction rate reaches 82.7%, the overall mass is greatly reduced, the maximum deformation is within a reasonable range, and the collision resistance is optimised.

Investigation of the dynamic compression behavior of 3D braided composites based on a virtual fiber embedding method

The three-dimensional braided composites (3DBCs) possess a complex spatial structure, which can lead to microscopic deformation of fibers under high-speed impact. This paper proposes a quasi-fiber scale model using virtual fiber-embedded (VFE) method to simulate the impact behavior and failure of 3DBCs. The results reveal that the maximum eccentricity of the VFE model yarn cross-section is 0.318, representing a 194% improvement compared to solid yarns. According to the characteristics of damage, it can be deduced that interactions among fibers play a pivotal role in determining the failure behavior of composites, particularly concerning non-linear changes. The modulus, strength and the time of initial damage rise with an increasing braiding angle, whereas the resin stress, yarn stress, and degree of damage exhibit opposite trends. The stress distribution over the braiding path shows that the main load-bearing component at 20° braiding angles is internal yarns, whereas the surface yarns take precedence at 40°. The maximum deformation of the yarn cross-section always occurs at the center of the shear band, with a maximum eccentricity of 0.456 at 20° braiding angles. The deformation in yarn flexing and cross-section flattening cause an uneven distribution of stress and strain, leading to localized damage and ultimately catastrophic destruction.

The Identification and Influence Factor Analysis of Landslides Using SBAS-InSAR Technique: A Case Study of Hongya Village, China

On 1 September 2022, a landslide in Hongya Village, Weiyuan Town, Huzhu Tu Autonomous County, Qinghai Province, caused significant casualties and economic losses. To mitigate such risks, InSAR technology is employed due to its wide coverage, all-weather operation, and cost-effectiveness in detecting landslides. In this study, focusing on the landslide in Hongya Village, SBAS-InSAR and Sentinel-1A satellite data from July 2021 to September/October 2022 were used to accurately identify the areas of active landslides and to analyze the landslide deformation trends, in combination with the geological characteristics of the landslides and rainfall data. The results showed that strong deformation was detected in the middle and back of the landslide in Hongya Village, with a maximum deformation rate of approximately -13 mm/year. The surface of the landslide consisted of mainly Upper Pleistocene wind-deposited loess, which is extremely sensitive to water. The deformation of the landslide was closely related to the rainfall, and the deformation of the landslide increased with the increase in rainfall. The research results prove that the combination of ascending and descending orbit data based on SBAS-InSAR technology is highly feasible in the field of landslide deformation monitoring and is of great practical significance for landslide disaster prevention and mitigation.

Application of a novel machine learning model for the prediction and optimization of anti-blast performance of sandwich honeycomb blast walls

Sandwich honeycomb blast wall with the superior energy absorption characteristics could be applied to anti-blast protection of offshore oil and gas platform. Recently, machine learning technique, as an alternative to traditional Finite Element Analysis (FEA), is becoming a powerful tool in understanding structural performance. The aim of this study is to propose a novel data-driven model for fast predictions of structure response of sandwich blast wall under explosion, including the maximum deformation δmax, the maximum internal energy Emax and the energy absorption ratio RE. FEA was firstly conducted to generate sample data for the proposed model by using LS-DYNA software. An improved artificial electric field algorithm (IAEFA) was combined with artificial neural network (ANN) to develop an IAEFA-ANN model. In case studies, the prediction results of IAEFA-ANN approximate the results of FEA well, and comparison results of 9 different ANN models demonstrate that IAEFA-ANN model has the best performance. Then, the effects of explosion parameters (including explosive charge mass Me, stand-off distance d and concave angles θ) on structural response prediction results were investigated by using the proposed model. Moreover, the IAEFA-ANN model was applied to conducting optimal design of the blast wall to obtain optimum anti-blast performance.

Bio-inspired helicoidal hemp/basalt/polyurethane rubber bio-composites: Experimental, numerical and analytical ballistic impact study with residual velocity prediction using artificial neural network

Recent body armour trends emphasize mobility, flexibility, and cost reduction while maintaining ballistic effectiveness through the use of natural fiber composite. This study evaluates the ballistic impact performance of soft and hard armor using experimental, analytical, numerical, and machine learning methods. We developed a soft armor bio-composite using monolithic, hybrid, and helicoidal structured Hemp (H)/Basalt (B)/Polyurethane (PU) rubber and tested its V50 ballistic limit according to Millitary-Standred-662 F. For hard armour, a multi-layer armor system (MAS) consisting of Al2O3/SiC ceramic, intermediate soft armour bio-composites, and an Aluminum (Al)-5052 plate backing was tested with armour-piercing bullets as per National Institute of Justice (NIJ)-0101.06 standards (Level IV). Soft armor performance was evaluated using macro-homogeneous finite element (FE), the Ipson-Retch analytical, and an Artificial Neural Network (ANN) regression model. Results showed minimal discrepancies from experimental data, with differences of 13.33 %, 12.08 %, and 8.08 % in V50 ballistic limit. The mechanical and thermal behaviors of bio-composites were assessed using un-notched Charpy, FTIR, and TGA methods. Helicoidal laminates improved Charpy toughness by 9.44 %, 19.30 %, and 40.28 % compared to hybrid and monolithic ([H]15 and [H]10) laminates, and exhibited lower weight reduction at high degradation temperature of 395.76 ℃. Helicoidal laminates increased V50 ballistic performance by 155.80 %, 76.22 %, and 16.61 % compared to [H]10, [H]15, and hybrid laminates, respectively. Due to spiral load distribution reduces stress concentration and enhanced the damage resistance of the laminate. Stand-alone soft armor demonstrates crater formation and radial cracks (petaling) due to fiber wedging and the shearing effect of a bullet. In conclusion, MAS revels a maximum back face deformation (BFD) of 18.06 mm. Al2O3/Helicoidal/Al-plate MAS reduced weight and cost by 69.21 %, and 233.72 % compared to Kevlar™-based MAS, promoting sustainable, lightweight, economical designs. Due to its higher fracture toughness and lower density, SiC ceramic in MAS provides lower trauma and further reduced weight compared to Al2O3 ceramic.