High Impact Forces Research Articles

Simulation and Analysis of Double Compound CAM Pusher Tool Changing Mechanism for NC Machine Tool

The core mechanism of existing CNC tool changers is typically a single composite cam swinging rod linkage. This setup has two main drawbacks: amplified vibration errors and high impact forces due to the swinging rod. To address these, this study focuses on CNC tool changers, specifically selecting the up-and-down motion follower and proposing a novel double composite cam push rod type mechanism. Solid modeling for both mechanisms was conducted using Creo and Matlab, and theoretical modeling of the contact forces for each follower type was completed. Comparative analysis shows the push rod follower exhibits lower contact forces than the swinging rod. Using the Adams platform, the dynamic characteristics of both mechanisms were analyzed, leading to an optimized design for the push rod type. An experimental model, scaled to 0.5, was built to compare experimental data with simulation results. The findings verify the accuracy of the models, supporting the feasibility of the push rod type tool changer.

Experimental study on aeration characteristics of plunging wave impact on a vertical cylinder

The impact force exerted by plunging breakers on structures is most pronounced, with the impact pressure being most sensitive to the changes in air entrainment, posing a threat to the structural safety of offshore wind turbines. However, the current explanations of the high impact force mechanisms in plunging waves are relatively superficial, and the relationship between the air entrainment motion and pressure oscillations remains unclear. According to the experimentally obtained pressure characteristics and the formation of entrapped air, this paper systematically divides the process of plunging wave impact on a vertical cylinder into three stages: breaking wave crest impact, entrained air cavity impact, and plume impact. Employing a bubble image velocimetry platform to visualize flow field characteristics and quantify turbulence intensity, we investigated the connection between gas motion and impact loads. The results indicate that the conversion of gas energy is closely related to the load characteristics, with the maximum impact force occurring near the peak of the energy gradient. The gas movement significantly influences pressure oscillations, which are positively correlated with the gas's physical compression and expansion characteristics. This study has uncovered new insights into the phenomenon of plunging waves impacting wind turbine towers and has enhanced the understanding of its load characteristics.

Porous Magnetic Soft Grippers for Fast and Gentle Grasping of Delicate Living Objects.

Magnetic soft grippers have attracted intensive interest due to their untethered controllability, rapid response, and biological safety. However, manipulating living objects requires a simultaneous increase in shape adaptability and gripping force, which are typically mutually exclusive. Increasing the magnetic particle content enhances the magnetic strength but also increases the elastic modulus, leading to low adaptability and high impact force. Here, a porous magnetic soft gripper (PMSG) is developed by integrating a porous structure into a magnetic silicone elastomer. The design of porous hard magnetic composite is characterized by high magnetization, low modulus, and rough surface. It offers the PMSG good compliance, high gripping force, and low impact force at fast gripping. The PMSG is capable of performing a variety of tasks, including the fast and gentle grasping of delicate living objects. The study provides insight into the design of novel magnetic grippers and may offer a promising outlook for biomedical or scientific applications in the manipulation of delicate organisms.

A novel machine learning framework for impact force prediction of foam-filled multi-layer lattice composite structures

Numerical simulations can provide valuable insights for the optimization of design and operational management; however, they are often impractical and computationally intensive. Machine learning methods are appealing to these problems due to their sufficient efficiency and accuracy. In this study, a novel framework for predicting the impact responses of foam-filled multi-layer lattice composite structures (FMLCSs) was proposed by combining the accurate finite element (FE) analyses, surrogate models, fast Fourier transform (FFT) method, and inverse FFT (IFFT) method. Firstly, reliable FM models were established to simulate the crashworthiness of the five FMLCSs under impact loading, including an analysis of energy transformation. Subsequently, surrogate models, namely radial basis function (RBF), polynomial response surface (PRS), Kriging (KRG), and back propagation neural network (BPNN), combined with methods of FFT and IFFT, were employed to predict the impact force-time series of the FMLCSs. More than 1000 frequency points were employed for each type of FMLCS, and all the R-square (R2) values of the established surrogate models exceeded 0.95, indicating that the proposed framework accurately predicted the impact duration and impact responses in the frequency domain. In addition, parameter sensitivity analysis revealed that a high peak impact force was accompanied by a short impact duration. Moreover, increasing the lattice-web height resulted in a significant increase in the impact duration.

Stress Distribution in Proclined Anterior Teeth of Pediatric Patients With and Without Mouthguard Use: A 3D Finite Element Analysis.

Traumatic dental injuries related to sports are a significant concern, as they can have severe physical and psychological impacts on children. Using mouthguards is essential, particularly in sports like skating, where high-impact forces are common. The study aimed to evaluate how stress is distributed on the teeth and surrounding bone in children with proclined anterior teeth when a force of 614.12 N was applied to two different regions of the jaws. The evaluation was conducted using finite element analysis (FEA), both with and without the use of a mouthguard. A 3-dimensional finite element analysis (FEA) model was constructed using a cone beam computed tomography (CBCT) scan of a 12-year-old male patient. An average standardized force of 614.12 N was calculated, based on the average weight of children aged 11 to 13 years and the average speed of 13.4 m/s with which the children skate. The force was applied in two different directions and areas of the jaws: a lateral blow, perpendicular to the crown and root with the maxillary and mandibular teeth in occlusion (between the first molar and second premolar), and a blow obliquely at the pogonion point on the chin. Static simulations were then performed for four realistic scenarios-two with mouthguards and two without mouthguards. The Von Mises stresses were evaluated under all conditions. When the applied force was directed laterally, the stress values observed were 126.76 MPa with a mouthguard and 140 MPa without a mouthguard. When the force was applied to the chin region, the stress values were 37.997 MPa with a mouthguard and 40.67 MPa without a mouthguard. The use of a mouthguard in children is beneficial for protecting teeth and surrounding structures, especially in cases of proclined anterior teeth, as it helps dampen the generated stresses.

Experimental Analysis of Cavitation Erosion: Parameter Sensitivity and Testing Protocols

The scientific goal of this study was to investigate the effects of various parameters on cavitation-induced erosion, with the aim to enhance the understanding and assessment of cavitation resistance in hydraulic systems. Cavitation erosion poses significant challenges to the durability and efficiency of hydraulic components, such as those found in hydropower plants and pumping stations. Prompted by the need to improve the reliability of cavitation testing and material assessment, this research conducted a comprehensive sensitivity analysis of a cavitation jet apparatus (CJA). This study employed an experimental platform that consisted of a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample. By examining a range of orifice diameters, this research identified that smaller diameters led to increased erosion intensity, with the most pronounced effects observed at a diameter of 2 mm. Furthermore, various standoff distances (SoDs) were tested, which revealed that shorter distances resulted in greater erosion, with the highest impact noted at an SoD of 5 cm. This study also evaluated different nozzle geometries, where it was found that a 132° conical sharped edges nozzle, combined with an orifice diameter of 2 mm and an SoD of 5 cm, produced the most severe erosion. Conversely, chamfered edges nozzles and a commercial nozzle (MEG2510) with an SoD of 10 cm or greater showed reduced erosion. These results highlight that by standardizing the testing duration to 1200 s, the CJA could reliably assess the cavitation resistance of materials. This study established a clear relationship between increased pressure and higher impact forces, which led to more severe erosion. The findings underscore the effectiveness of the CJA in evaluating material resistance under various cavitation conditions, thus addressing a critical need for reliable cavitation testing tools.

Influence of surface curvature on the impact force of water droplet

Although the global market for wind energy is growing rapidly, leading-edge erosion is a critical issue hindering the development of wind power. The impact force of a droplet colliding with flat surfaces has been investigated in previous studies. However, the impact force exerted on curved surfaces, such as that experienced by eroded wind turbine blades, is not well understood. This study discusses the relationship between the impact force generated on a solid surface by a water droplet and the radius of curvature of the impacting surface. The impact force by a droplet was measured using a force sensor mounted on semi-cylindrical caps with different radii of curvature. The measurement results showed that the impact force decreased as the radius of curvature decreased. A computational fluid dynamics model solving incompressible flows showed that, unlike the case of a curved surface, the initial momentum of the droplet was mostly transferred to the flat surface. This resulted in a high impulse for an impact with a flat surface. The falling droplet was blocked by the surface, and the lateral jet was accelerated sideward. This acceleration was moderate for curved surfaces. When colliding with a flat surface, a higher impact force was generated owing to the wider area of the excited surface pressure compared with that of the curved surface. Finally, the relationship between the peak of the impact force and the surface curvature was derived, suggesting that the force peak is inversely proportional to the curvature.

A Five-Year Overview of Bicycle Injuries in the United States Between the Years 2017 and 2021.

Introduction This study investigates the changes in bicycle-related injury rates between 2017 and 2021. We focus specifically onchanges in age demographics, and the most common diagnosesand body parts injured. Methods We queried the National Electronic Injury Surveillance System (NEISS) for injuries associated with bicycles from 2017 to 2021. Chi-square analysis was used to evaluate trends in injuries vs. time for the entire sample, age groups in five-year increments, and the proportion of injury types by diagnosis and body part. Results The highest annual injury rate (12,800 counts) occurred in 2020, coinciding with the COVID-19 safer-at-home order. Pediatric patients continue to make up the majority of injured cyclists (48% of patients are younger than 19 years), but their percentage is decreasing (zero to four years (-13%, p < 0.005), five to nine years (-17%, p < 0.005), 10-14years (-5%, p < 0.005), 20-24years (-16%, p < 0.005), 25-29 years (-2%, p < 0.005), and 50-54 years (-14%, p < 0.005)) and mirrored by an increase in the proportion of older injured cyclists (40-44years (+26%, p < 0.005), 60-64years (+44%, p< 0.005), 65-69years (+69%, p < 0.005), and 70+years (+57%, p < 0.005)). The past five years saw an increase in injuries associated with higher impact forces and the potential for more severe morbidity and mortality, such as internal organ injuries (+13%, p < 0.01). The incidence of concussions, however, has not changed significantly. The extremities are the most commonly injured body parts(upper and lower arm, elbow, wrist, hand, fingers, upper and lower leg, knee, ankle, foot, and toe = 47% total) and continue to increase in frequency (lower arm (+2%, p < 0.005), lower leg (+3%, p < 0.01), upper arm (+18%, p < 0.005), and hand (+11%, p < 0.05)), while facial injuries are becoming less common(-3%, p < 0.05), and head injuries have not experienced a significant change of incidence. Conclusion Although there was an increase in bicycle-related injuries during the COVID-19 safer-at-home order, numbers have since returned to pre-COVID-19 levels. Other changes in bicycle injury demographics and mechanisms, such as a rise in older adult cyclists and high-force mechanism injuries, however, call for a re-evaluation of preventive and treatment priorities.

A platform for continuous monitoring of the degradation of aluminum beverage can lids in realistic conditions through electrochemical impedance spectroscopy

The coatings on aluminum beverage can lid interiors can be prone to long-term degradation due to the high impact forces during fabrication and the corrosive nature of beverages. Multi-month tests are required to assess their resistance to this degradation. This study aims to present an innovative can lid coating testing method that incorporates in-situ Electrochemical Impedance Spectroscopy (EIS) monitoring under real-world conditions and with actual beverages. A robust testing chamber was meticulously engineered to house the 3D-shaped lid and maintain the conditions found in a beverage can. Experiments were conducted at stressed and non-stressed conditions, assessing different coatings and different beverages. The developed method has the potential to mimic the multi-month pack tests and offers a quicker, more insightful, and less laborious alternative for the lid coating degradation assessment. Ultimately, this method could help in improving the longevity and quality of aluminum beverage cans.

Investigating low velocity impact and compression after impact behaviors of carbon fiber/epoxy composites reinforced with helical multiwalled carbon nanotubes

Pre-damage and undetected micro-defects in fiber-reinforced polymer (FRP) composites are significant challenges compromising the integrity and mechanical performance of composite structures in aerospace applications. To address this challenge, this experimental study investigated the low velocity impact (LVI) and compression after impact (CAI) behaviors of carbon fiber/epoxy (CF/E) reinforced with 0.0 (control sample), 0.2, and 0.4 wt% helical multiwalled carbon nanotubes (HMWCNTs). The LVI test results showed that the control samples, with epoxy as the predominant phase, registered the lowest peak force compared to the 0.2 wt and 0.4 wt% HMWCNT/epoxy composite laminates. The CAI test results showed a decrease in strength with increased impact energy and an increase in the weight percent of HMWCNTs. Consequently, the 0.4 wt% HMWCNT ladened composites could withstand higher load without undergoing significant deformations, exhibiting the highest impact resistances due to the presence of CNTs, which function as load-bearing material. The HMWCNT interleaved CF/E composite laminate samples subjected to 25 J of impact energy achieved a higher maximum force of 9870.25 N compared to 8527.26 N for the damaged samples at the same level of impact energies. This fact indicates that the damaged samples could not withstand sufficiently high impact forces due to local instability arising from existing damages. The results strongly suggest a high potential for HMWCNTs CF/epoxy laminate composites in making structural and substructural components in aircraft and automobiles due to their proven superior properties.

A printable shear stiffening composite with enhanced fracture toughness and impact resistance for intelligent wearable applications

The continuous advancement in shear stiffening materials has sparked innovation in the field of flexible wearable devices. However, conventional preparation techniques for these materials have drawbacks such as limited toughness and lack of structural design. Herein, we propose a convenient fabrication method for shear stiffening elastomer (SSE) composite using a direct-ink-writing (DIW) assisted manufacturing technique. The influence of SSE structural design strategy on the mechanical behavior of composite is comprehensively investigated using crack propagation and dynamic impact experiments. Benefiting from the mechanically complementary effect of two-phase materials, coupled with robust interfacial adhesion, the composite with a densely arranged rectangular SSE structure exhibits high fracture toughness (2776.10 J⋅m−2) and impact force dissipation (61.78 %). Further, by integrating the printable composite with deep learning-based wireless sensing modules, a wearable elbow pad with attractive man–machine interaction is developed, which verifies the broad application prospect of this composite in intelligent protection.

Sports-Related Cervical Spine Injury: A Series of Two Cases with Literature Review

AbstractSports-related cervical injuries pose a significant concern in the realm of sports medicine, affecting athletes across various disciplines and levels of competition. Cervical injuries in sports primarily result from a combination of high-impact forces, sudden acceleration–deceleration movements, and improper techniques. Common cervical injuries include sprains, strains, fractures, and more severe conditions such as cervical spine dislocations. The mechanisms underlying sports-related cervical injuries involve complex interactions between biomechanical forces, player dynamics, and environmental factors. Understanding the biomechanics of these injuries is crucial for developing effective preventive strategies. This study highlights the mechanism of injury, primary intervention including transport of athletes, and medical and surgical management with the help of two such cases managed in a single institute in this year, 2023. By addressing the multifaceted aspects of these injuries, the sports community can strive toward creating a safer environment for athletes and minimizing the impact of cervical injuries on their overall well-being and athletic performance.

Design and application of FBG shock sensor for high-G shock tester and a wider frequency range

This study explores the potential of employing arrays of FBG shock sensors to measure strain in high-G impact test systems. Through a meticulously designed experiment, we installed three FBG arrays into grooves on the bottom surface of high-impact test equipment, ensuring a seamless profile. The unique design of the double elastic mass induced acceleration in the grating fiber while simultaneously subjecting it to stretching or compression in the opposite direction. This innovative approach allows us to evaluate the feasibility and effectiveness of utilizing FBG vibration sensors for precise strain measurement in high-G impact scenarios. The natural frequency and sensitivity of the sensor were theoretically investigated and optimized using MATLAB software. Furthermore, ANSYS was used to analyze the models and conduct simulations. The simulated FBG sensor had a natural frequency of 5000 Hz and demonstrated a flat frequency range of 100–3500 Hz. The linearity of the average sensitivity is 2.77 pm/G. A high-impact FBG shock sensor can measure high-impact forces or vibrations accurately, including aerospace to monitor aircraft health, automotive to improve vehicle safety, defense to detect gunfire, and sports to monitor the impact of collisions and improve athlete safety.

Multi-Objective Optimization of Absorber Piston Rod Design Parameter using Response Surface Methodology

Car absorbers provide a comfortable ride and improve ride handling by delivering road wheel contact. The typical car absorber problems are oil leakage and piston rod wear-out due to the lateral friction between the shell case and piston rod. The piston rod can bend and rupture when exposed to higher vibration exerting high impact force. This study focuses on optimizing car absorber piston rod design parameters via finite element analysis. The response surface methodology (RSM) was utilized to create the design of the numerical experiment. The piston rod parameters (i.e., length of the piston rod, the piston rod diameter #1, and the piston rod diameter #2) were optimized to reduce the stress and displacement of the piston rod. The optimization results revealed that the optimum parameters were 254 mm in piston length, 24.79 mm in diameter #1, and 15 mm in diameter #2. With the optimized piston rod parameters, the stress and displacement of the piston were 1.65048E+007 and 0.007569 mm, respectively. The most significant factors that influence the responses were also studied. The suggested optimized factors and responses were validated in the finite element simulation.

Accessing quasi-static impact process by 3D-NPR corrugated metamaterials

The conventional impact process is a quintessential impulse process that causes substantial damage due to the high initial impact force. However, the impact effect can be significantly diminished by making the impulse process quasi-statically by using a three-dimensional negative Poisson's ratio corrugated metamaterial (3D-NPRCM) structure. This paper proposes a novel 3D-NPRCM obtained by folding the 2D-NPRCM. This study examines the crashworthiness properties and impact force of 3D-NPRCM subjected to impact using the finite element method (FEM). The results reveal that the sequential matrix structure has the ability to make impact impulse processes quasi-statically. The effects of various folding angles, arrangements, and geometrical parameters on the properties are also explored. Finally, the 3D-NPRCM is employed in an automobile crash box design. Through axial quasi-static compression simulation, the peak crushing force of the 3D-NPRCM crash box is reduced by 25.374 % from 211.652 kN to 157.946 kN, and the energy absorbed is increased by 23.830 % from 11.259 kJ to 13.942 kJ, compared to the conventional crash box. Through cart lateral impact simulation, the peak crushing force of the 3D-NPRCM crash box is reduced by 18.076 % from 206.9 kN to 169.5 kN, and the compressive displacement is decreased by 9.457 % from 235.8 mm to 213.5 mm. This work presents a novel design proposition for a crash box in vehicle engineering and demonstrates a fresh approach to expand the design of three-dimensional mechanical metamaterials.

The relationship between repeated impacts and CAI strength of sandwich structure considering different impactor shape in individual impact

Sandwich structures are susceptible to repeated impact loads, and each individual impact is not nearly identical to the previous one, especially for repeated impacts under different impactor shapes such as hail impact. Therefore, the repeated impact behavior using different impactor shape in individual impact of polymethacrylimide (PMI) foam sandwich structure is studied and discussed through experiments and finite element (FE) simulations in this paper. The representative mechanical characteristics such as impact responses, damage modes, and energy absorption are investigated until penetration occurs, and the mechanism of impact damage accumulation between impact events with different impactor shapes is revealed. Besides, the compression after impact (CAI) strength is utilized to assess the residual strength of sandwich structure under repeated impacts. It indicates when the contact area between the specimen and impactor is larger, it can result in a higher impact force, a shorter contact duration, and potentially reduce the extent of damage. The matrix damage is the main damage mode, and the proportions of matrix tension and compression are nearly constant, with a ratio of approximately 2:1. In addition, the proportion of the impact energy absorbed by foam core increases as the number of impacts increases. When the impact energy is low, the CAI strength is sensitive to the number of impacts, the shape of impactor, and the sequence of impactors, but the similar phenomenon does not occur at higher impact energy. The present study provided a series of experimental and numerical results, which could be utilized as design reference guidance in the designing of composite sandwich structures.

Application of Microfluidization in the Food Industry

Microfluidization is a high-pressure homogenization technique that applies a number of forces such as high impact force, shear force, sudden pressure drop, and cavitation force in order to subdivide the particles into smaller sizes. The technology of micro fluidization is based on a double-acting intensifier pump and an interaction chamber. The intensifier pump creates the pressure required to force the raw material into the interaction chamber. It is widely used in the food industry for a variety of applications, including the formation of micro- and nano-sized emulsions, the encapsulation of easily degradable bioactive compounds, and the enhancement of functional properties of proteins, polysaccharides, and dietary fibers. It was first used to emulsify milk products before being used in other food products such as fruit juices, proteins, gums, cereals, and cereal by-products.

Blunt weapons in the roman imperial army. A multidisciplinary approach to the clava from experimental archaeology to forensic anthropology

The wooden club (clava) is rarely associated with the image of Roman soldiers, perhaps because it was considered an unconventional weapon with ethnic attributes and/or specific combat roles. Nonetheless, it is attested in the archaeological record and some ancient texts. The panoply and the military career of the soldiers represented on the tombstones of Catavignus son of Ivomagus (1st century AD) and Marcus Aurelius Alexis (early 3rd century AD) offered us the possibility to reconsider the use of the club as an offensive weapon within the Imperial Roman army. The authors made a replica of the clava using historical tools and manufacturing techniques. A series of tests have then been performed to investigate the use of the club in combat. The possible traumas on human targets were also evaluated with a forensic anthropological approach. The results suggest the essential role of flexion and rotation of the kinetic chain «hip/shoulder/ arm» in wielding the clava. This movement requires a much more mobile combat style that can prove very effective against heavily armoured targets due to the weapon's high-impact force and a more extended reach than more conventional Roman sidearms.

ROBOT-ASSISTED TARGETED GAIT TRAINING.

Millions of people are affected yearly by "runner's knee" and osteoarthritis, which is thought to be related to impact force. Millions are also affected by chronic falling, who are usually both difficult to identify and train. While at first glance, these topics seem to be entirely disconnected, there appears to be a need for a device that would address both issues. This paper proposes and investigates the use of the Variable Stiffness Treadmill (VST) as a targeted training device for the different populations described above. The VST is the authors' unique robotic split-belt treadmill that can reduce the vertical ground stiffness of the left belt, while the right belt remains rigid. In this work, heart rate and energy expenditure are measured for healthy subjects in the challenging asymmetric environment created by the VST and compared to a traditional treadmill setting. This study shows that this asymmetric environment results in an increase in heart rate and energy expenditure, an increase in activity in the muscles about the hip and knee, and a decrease in impact force at heel strike. Compliant environments, like those created on the VST, may be a beneficial tool as they can: reduce high-impact forces during running and walking, significantly engage the muscles surrounding the hip and knee allowing for targeted training and rehabilitation, and assist in identifying and training high fall-risk individuals.

Mechanisms of dental injuries in basketball, United States, 2003-2022.

Oral injuries such as oral soft tissue lacerations and contusions can occur in basketball by mechanisms such as running into other players or falling. Given a high enough impact force, dental injuries such as tooth fractures and avulsions can occur. Previous research has studied the different types of oral injuries as well as the mechanisms that cause them. Yet, the mechanisms resulting in dental injuries have remained unexplored. The aims of this study were to investigate the distribution of different oral injuries within each injury mechanism and evaluate which mechanisms were most likely to lead to a dental injury. This is a retrospective cohort study using the National Electronic Injury Surveillance System (NEISS). Subjects who experienced oral injuries from basketball between January 1, 2003 and December 31, 2022 were included in this study. The independent variable was the injury mechanism. The dependent variable was the dental injury outcome (yes/no). Multivariate logistic regression was used to measure the association between the injury mechanism and the dental injury outcome. A p < .05 was considered statistically significant. This study included 4419 subjects who experienced oral injuries (national estimate, 138,980). Approximately 14.7% of oral injuries were dental injuries. Subjects experiencing collisions with objects such as walls or the basketball hoop (odds ratio (OR), 4.39; p < .001), falls (OR, 3.35; p < .001), or contact with the basketball (OR, 1.77; p = .006) had significantly higher odds of sustaining a dental injury relative to those experiencing contact with another player. Basketball players experiencing contact to the mouth have high odds of sustaining a dental injury. An understanding of injury mechanisms is important for medical teams to manage these injuries and for coaches to educate athletes on safe and proper playing styles. Furthermore, healthcare providers and basketball staff should encourage athletes to wear mouthguards to reduce the risk of traumatic dental injuries.