Impact Of Accidents Research Articles

Damage assessment of prestressed concrete containment vessels behaviour under blast induced fire loading

Recently, explosions, collisions, and fires have occurred frequently around the world due to terror attacks, and impact accidents. Particularly, since the 9.11 terror attack, public anxiety heightened due to lack of safety in our society. The incidents can be viewed as examples of possible extreme loading scenarios that can occur in structures and infrastructures. Among all of structures and infrastructures, prestressed concrete containment vessels (PCCVs) are the most vulnerable structures from terrors and accidents. Therefore, in this study, finite element software LS-DYNA and MIDAS FEA, are used to evaluate of PCCVs applied with blast induced fire loading resistance. Since the blast test on a full-scale PCCV is not realistically possible, it is necessary to develop a precise simulation tool to accurately evaluate the damage level of a full-scale PCCV. This study aims to improve the accuracy of the simulation tool by calibrating numerical software using experimental test data. Then, the parametric study is conducted according to the explosive charge weight, standoff distance, and concrete compressive strength of a PCCV using calibrated blast and fire simulation tools. Based on the study results, the level of damage assessment to PCCVs applied with blast-fire loading can be precisely evaluated.

Wandering airway foreign body in early infancy

Accidental impaction of objects in the respiratory passage is a life-threatening condition. A 9-month-old male infant was admitted with fever, cough and respiratory distress without history of choking. He was treated as wheezy bronchitis with appropriate therapy but, did not show response. HRCT showed an impacted foreign body in the trachea which caused a partial luminal compromise. Two attempts to remove foreign body by rigid bronchoscope failed, and tracheostomy was performed due to fall in oxygen saturation. After stabilization, again saturation was falling and air entry was absent on right hemithorax. Considering the possibility of movement of foreign body in right bronchus, bronchoscope was reintroduced and foreign body was removed in piecemeal. This process was complicated with cardiorespiratory arrest, twice from which the patient was revived. Postoperative period was uneventful. So, high index of suspicion is required to diagnose such a foreign body of the tracheobronchial tree to prevent morbidity and mortality.

Upper Gastrointestinal Foreign Body, our Experience in Faridpur Medical College Hospital

Accidental ingestion and impaction of food or non-food foreign body in upper GIT is not uncommon. This retrospective study was undertaken at Gastroenterology department of Faridpur Medical College Hospital, Bangladesh. Data were collected from endoscopy software by computer search among patients with foreign bodies in upper GIT from January 2012 to December 2018. Total 41 patients with endoscopically proved ingested with or without impacted foreign body in the upper GIT were studied. Of them, 28 were male and 13 were female with age ranges from 15 to 85 years with a mean age of 52.66 ± 19.7 years. Meat bolus was the commonest type (12; 29.3%), followed by dental prosthesis (9; 22%). Most of them (24; 58%) were impacted between 20 to 30 cm from incisor teeth. We could successfully remove 38 cases with a success rate of 92.7% with the help of dormia basket, polypectomy snare & rat tooth foreign body grasper. We found few erosions and superficial ulcerations at the impacted site among patients with dental prosthesis, pill with strip and chicken bone. One patient with sharp flat bone of hilsa fish was impacted at esophagus like sharp cutting blade and produced incised looking wound at both esophageal walls. In 19 cases (46.34%) we found definite anatomic abnormalities and 19 cases (46.34%) no abnormalities was found. Rest 3 cases, who were referred to surgeon we failed to know the underlying pathology. Sharp foreign bodies impacted at upper esophagus were difficult to remove endoscopically. Faridpur Med. Coll. J. Jul 2019;14(2): 74-78

Incidência de múltiplas fraturas faciais: estudo retrospectivo de 20 anos

As fraturas faciais têm incidência variável de acordo com idade e gênero do indivíduo, localização geográfica e aspectos culturais, posição socioeconômica, influência do clima e tempo, utilização de álcool e drogas, variação das legislações de trânsito, violência doméstica e fatores etiológicos. Com o objetivo de verificar a epidemiologia do trauma facial na região de Araçatuba – SP, foi realizado um levantamento retrospectivo de vinte anos a partir dos prontuários de pacientes atendidos no Serviço de Cirurgia e Traumatologia Bucomaxilofacial da Unesp Araçatuba, verificando a incidência, fatores etiológicos, faixa etária e gênero de pacientes que sofreram múltiplas fraturas de face. Os dados obtidos foram inseridos no EpiInfo, para a realização da contagem e estatística (Teste de correlação de Spearman). Foram avaliados 2770 prontuários, dos quais, 357 pacientes apresentaram mais de uma fratura na face. Foi observado que houve uma maior prevalência em pacientes do gênero masculino (p<0.05). O fator etiológico em destaque foi o acidente motociclístico seguido dos acidentes automobilísticos e a agressão física. Múltiplas fraturas em face são eventos muito frequentes nas emergências hospitalares, sendo que os homens são mais frequentemente atingidos, e os acidentes de alto impacto os que mais determinam a gravidade e a associação de fraturas faciais.

Discharging sinus from the eyelid following accidental impaction of wood fragment

Injury to the eyelid is one of the most common emergencies at eye hospitals. Injuries to the eye and its surrounding tissues may result from several types of foreign bodies. The injured eye must be carefully and gently examined to prevent missed injuries and to avoid putting pressure on the globe, which might cause prolapse of intraocular contents.
 We report an unsightly upper eyelid discharging sinus with wood fragment impaction that was incompletely removed by the first attending physician for a period of eleven months. The wood fragments were carefully and completely removed under local anaesthesia, and debridement and dressing of the wound were done by an ophthalmic plastic surgeon when the patient was eventually referred to the tertiary institution. The need to include basic eye care courses in continued medical education for all general practitioners is advocated to reduce resultant ocular morbidity from such ocular injuries. This will aid this group of physicians in decision-making while providing care to patients with eye injuries.

A study on motorcyclist head reponses during impact against front end of vehicle

Motorcycle to vehicle impact accidents occur frequently in real world and often cause serious brain injuries and deaths of motorcyclists. This study aims to research the motorcyclist head responses and helmet protection performance at common motorcycle-vehicle impact scenarios. First, multi-body system (MBS) models of motorcycle-vehicle impact were developed to investigate motorcyclist’s head and vehicle conditions (position, orientation and velocity) at the time of head impacts with vehicle. Then, the impact conditions were input to finite element (FE) models of head striking vehicle to obtain the head tissue level responses, such as coup pressure, von Mises stress, first principal strain and skull stress. Influences of impact velocity, impact angle, and helmet usage on head responses were investigated by conducting parametric studies. The results show that motorcycle and vehicle initial speeds and impact angles influence motorcyclists’ head impact locations on vehicles and head responses. Coup pressure and skull stress have strong relationships with head impact forces, while von Mises stress and first principal strain are sensitive to head equivalent impact velocity combining of normal and tangential velocities. Helmet shows a clear effectiveness in reducing brain pressure and skull stress, while its influences von Mises stress and first principal strain in brain subtly.

Effects of environmental exposure on the mechanical properties of composite tidal current turbine

In order to meet the growing demand for energy and also to fight against global warming, Renewable Marine Energies (RME) appeared as a great opportunity for a real ecological and industrial choice. Tidal current turbines are used to extract this energy and installed on the seabed at locations where the nozzle can be prone to the accidental impact and critical loads. The principal objective of this research is to investigate the effects of environmental exposure on the mechanical properties of composite tidal current turbine, the most advanced features currently available in finite element (FE) Abaqus/Explicit have been employed to simulate the behavior of the composite nozzle under static and dynamic loading conditions. To investigate this situation, a parametric analysis is conducted which deals with the effect of velocity and geometry of the impactor. The mechanical behavior has been analyzed as both kinematic effect due to deflection of the composite structure and dynamic effect caused by the interaction between the impactor and the hydrodynamic and hydrostatic pressures over the loading. The stress and the deformation distribution are presented. On the other hand, damage modeling was formulated based on Hashin criteria for intra-laminar damage. This has been accomplished by forming a user-created routine (VUMAT) and executing it in the Abaqus software.

A Probabilistic Analysis Of Operation Of A Flat Steel Frame Under Seismic Action

The seismic action is non-stationary random process. Calculation in the probabilistic setting makes it possible to most accurately assess the response of the system during an earthquake. In the work, the reliability of a flat steel frame under seismic action was estimated by the method of statistical tests when considering seismic action in the form of a non-stationary random process. The design cross-sections of the frame were adopted based on the results of the calculation of the seismic action of the design earthquake level in accordance with current design standards. When performing the probabilistic calculation, a deterministic solution implemented in the software package was used. The solution is based on direct integration of the equations of motion using explicit schemes. A method has been developed for determining the actual value of safety coefficient of load-bearing capacity of the frame. Considering the safety factor of the frame under seismic action as a random variable, a corresponding histogram is constructed using the criterion of non-collapse. Using the Pearson criterion, the closest theoretical distribution law to the obtained empirical distribution is determined. According to the theoretical laws produced, the assessment of the actual safety factor of the bearing capacity and the coefficients taking into account possible damage to buildings and structures with a given security. In addition, the probability of plastic deformations exceeding the value of 0.05 in the structural elements in case of accidental seismic impact of the maximum calculated earthquake level was established by statistical tests. The method is used to determine the seismic stability of structures with a given security, which makes it possible to provide the required level of reliability for all buildings and structures designed in seismic areas.

Numerical Modeling and Performance Assessment of FRP-Strengthened Full-Scale Circular-Hollow-Section Steel Columns Subjected to Vehicle Collisions

Axial load-bearing structural members often experience significant damage or failure when subjected to moving-vehicle or vessel collisions. Hollow steel tubular columns are highly vulnerable under transverse impact loading. Thus, strengthening/retrofitting of existing steel tubular columns may be required if these members are not designed to withstand expected transverse impact from transport accidents. This paper investigates the performance of full-scale circular-hollow-section (CHS) tubular columns strengthened with fiber-reinforced polymer (FRP) and subjected to vehicular impact. Initially, finite-element (FE) models of bare and FRP-strengthened CHS medium-scale specimens were developed to conduct transverse impact analysis for the model validation purpose. The impact simulation results were compared with the drop-mass impact test results and good agreements were found between the FE and experimental tests. The validated FE models were extended to full-scale bare and FRP-wrapped CHS columns. The full-column vehicle collisions were simulated using a realistic vehicle model by considering varying axial static forces and vehicle impact velocities. The results showed that strengthening with carbon-fiber-reinforced polymer (CFRP) improved the impact resistance capacity of a bare CHS column by preventing plastic hinge formation due to excessive local buckling when subjected to accidental vehicular impact. Three-layer CFRP strengthening proved to be an effective strengthening system compared with two-layer CFRP strengthening system. The effect of load eccentricity was assessed further, and it was found that CFRP strengthening contributed significantly to preventing the failure of CHS columns with varying eccentricities when subjected to credible vehicular impact events.

Implications of impact experiments on honeycomb shielded exterior beam-column joint

The response of building structures under impact loads is a challenging subject for both numerical and analytical studies, as the available experimental data is limited. In the current research, an attempt was made to study the experimental investigation on the exterior beam-column joint against accidental and intentional impact loading. The velocity regime of the projectile was considered in the range 30–34 m/s. The response of the structural member shielded with the Aluminum honeycomb sandwich panel was compared with the unshielded beam-column joint. The target damage, failure modes, energy absorption, and evolution of cracks were examined in terms of both analytically and experimentally. Results obtained from high-speed imaging were used to obtain the projectiles incident, residual, and re-bound velocities. The application of honeycomb shielding on the seismic group specimens shows that the ballistic limit was increased by its energy absorption characteristics. It was found that they have a 22% higher ballistic limit than that of the seismic group specimens without honeycomb shielding. The shielded honeycomb sandwich panel specimens show promising results as they absorbed 49% higher impact energy than that of seismic specimens without honeycomb shielding. The current study provides a valuable reference for designing of honeycomb panels as a sacrificial material to safeguard the engineering structures against impact loads in the intermediate velocity regime.

Evaluation of injury thresholds for predicting severe head injuries in vulnerable road users resulting from ground impact via detailed accident reconstructions.

The aim of this study was to evaluate the effectiveness of various head injury criteria and associated risk functions in prediction of vulnerable road users (VRUs) severe head injuries caused by ground impact during vehicle collisions. Ten VRU accidents with video information were reconstructed by using Chalmers Pedestrian Model, vehicle multi-body system models and the THUMS (Ver. 4.0.2) finite element model. The head kinematics were used to calculate injury risks for seven head kinematics-based criteria: head angular velocity and acceleration, linear acceleration, head injury criterion (HIC), head impact power (HIP) and two versions of brain injury criterion (i.e., BRIC and BrIC). In addition, the intracranial responses were used to estimate seven tissue injury criteria, Von Mises stress, shear stress, coup pressure (C.P.) and countercoup pressure (CC.P.), maximum principal strain (MPS), cumulative strain damage measure (CSDM), and dilatation damage measure (DDM). A review of the medical reports for all cases indicated that each individual suffered severe head injuries and died. The injury risks predicted through simulations were compared to the head injuries recorded in the medical or forensic reports. The results indicated that 75-100% of the reconstructed ground impact accidents injuries were correctly predicted by angular acceleration, linear acceleration, HIC, C.P., MPS and CSDM0.15. Shear stress, CC.P. and CSDM0.25 correctly predicted 50-75% of the reconstructed accidents injuries. For angular velocity, HIP, BRIC and BrIC, the injuries were correctly predicted for less than 50% of the reconstructed accidents. The Von Mises stress and DDM did not correctly predict any reconstructed accidents injuries. The results could help to understand the effectiveness of the brain injury criteria for future head injury evaluation.

Estimating traffic change in accidental regional node failure for Asia pacific IP networks

Connectivity seems to be one of the significant features of today’s life. People rely on their technology in almost every aspect of their daily living. They also depend on this technology to be accessible anytime and anywhere. It is true that technology has touched every feature of today’s life. However, it is the networks that allowed this touch to reach almost everyone, regardless of who or where they are. Disasters stand for the oldest challenges that ever faced humanity. Since societies are extremely dependent on the technology, it is imperative to face the challenge in terms of technological communication systems. In this paper, the Accidental Disaster Network Impact Model is used to study the impact of a regional computer network failure triggered by an accidental disaster on the surviving network. The main aim is to study the percentage of change in traffic and lost traffic in node failure scenarios. This research estimates the change in traffic in cases of single node failure and double node failure. Also, it addresses the case of partial node failure in which only part of the communication ability is lost. The research also generates a simplified network map that represents the regional network of Asia Pacific.

Investigation of mechanical property of cylindrical lithium-ion batteries under dynamic loadings

Understanding of mechanical property of lithium-ion batteries is the key to unlock complicated and coupled behaviors of thermal runaway, which is triggered during electric vehicle collision. In this study, mechanical behaviors of cylindrical lithium-ion batteries under dynamic loadings are investigated. Two types of 18650 lithium-ion batteries, namely LiNiCoAlO2 and LiNiCoMnO2, are chosen to perform compression tests at various dynamic loadings. Experimental results indicate that these two types of 18650 lithium-ion batteries exhibit strain rate hardening behaviors, namely their resistances to deformation enhance as loading rate increases. LiNiCoMnO2 batteries show obvious strain rate hardening behaviors at low loading rates while LiNiCoAlO2 batteries can only show strain rate hardening behaviors until the loading rate increases to a certain value. The constitutive model of the jellyroll of lithium-ion batteries is proposed to describe these mechanical behaviors under dynamic loadings and it is validated by a finite element model of lithium-ion batteries. The proposed constitutive model can be utilized to evaluate the crashworthiness of lithium-ion batteries in the case of impact accidents and provide valuable guidance for the structure design of battery packs in electric vehicles.

Vibration energy harvesting with piezoelectric ceramics working in d33 mode by using a spring-mass-spring oscillator

This paper proposed a piezoelectric energy harvester based on a spring-mass-spring oscillator, of which the piezoelectrics operate in the d33 mode. Theoretical analysis reveals that the spring-mass-spring oscillator can not only generate a larger vibration than that of the ambient system but also buffer the force of possible accidental impact applied on the piezoelectric stacks. By using lead zirconate titanate (PZT-4) ceramics as model materials, we systematically characterized the performance of the energy harvester. Results show that at the resonance frequency, the harvester can output a satisfactory electric field. In addition, it has excellent fatigue resistance, e.g., under 9 g vibration acceleration for a long time about 12 h, the electric voltage output of the harvester nearly kept constant and only a slight fluctuation was observed.

Development of large-scale bistable motion system for energy harvesting by application of stochastic resonance

Stochastic resonance has become an important topic in the collection of environmental vibrational energy; however, realization of sufficiently large-scale motion for effective energy harvesting remains a difficult problem. Therefore, unlike the conventional vibrational systems that use cantilever beams, this study proposes a novel bistable motion system based on application of an elastic spring that diagonally supports a lumped mass block that can move freely along a straight rail. Using a combination of theoretical analysis, numerical simulation, and experimental verification, it is shown that stochastic resonance phenomena can be activated reliably using the proposed bistable motion system, and correspondingly large-scale bistable responses can be generated to realize effective amplitude enlargement after input signals are received. Additionally, it is demonstrated that large amplitude motion can be achieved with a highly robust performance because the rail-guided motion can suppress the effects of accidental impact from the outside. Furthermore, as an important design factor, the influence of periodic excitation signals on the large-scale bistable motion activity is carefully discussed and a solid foundation is laid for further practical energy harvesting applications.

Affecting of the Long-Term Deformation to the Stability of RC Frame-Bracing Structural Systems under Special Accidental Impacts

The paper is devoted to investigation of the loading duration affecting to stability of structural elements of reinforced concrete building frames at post-critical states caused by the sudden removal of one of the load-bearing constructions. Modelling of strength and deformation characteristics of reinforced concrete under long-term loading was performed using the theory of plasticity of concrete and reinforced concrete proposed by G.A. Geniev. Following to this theory, the rheological model of long-term strength of concrete was presented by two elements connected in series, one of which characterizes the process of short-term loading, and the second viscous element corresponds to the Kelvin-Voigt model and takes into account the processes of long-term deforming. It was established that at long-term loads acting to operated reinforced concrete structural system the value of critical force corresponding to loss of stability of the structural element decreases. This fact should be taken into account when assessing the resistance of such building frames to progressive collapse under special accidental impacts caused by removal one of load-bearing elements of a structural system.

Robotic System for Catheter Navigation during Medical Procedures

Lung cancer is the most common cancer globally with over 2 million new cases diagnosed every year. Fortunately, if caught early, the likelihood of survival is greatly improved. If diagnosed in Stage I, survival rates are >75% over 5 years, vs. just 1% if diagnosed in Stage IV. Early diagnosis requires finding and sampling (biopsy) small, peripheral nodules that are located in the parenchima of the lung and predominately outside small airways. Currently, for early diagnosis a bronchoscope is inserted into the lung airway but due to large size it cannot reach the small airways. Therefore, the doctor has to advance a sharp biopsy needle blindly from the tip of the bronchoscope and into the lung tissue in the approximate direction of the nodule. This blind procedure has low accuracy and carries a high risk of misdiagnosis. Currently, to improve the accuracy, real time x-ray (fluoroscopy) is use which causes exposure of the patient and physician to harmful radiation. Computer and image assisted surgery and medical robotics present viable solutions but are not optimal at present. The scope of our research was to develop a robotic solution for increased precision and accuracy of early diagnosis and treatment of lung cancer, to increase procedure success rate, decrease patient radiation and stress exposure, and reduce the procedure cost. For this purpose, we developed an advanced prototype of a robotic system which is small in size, easy to use and effective. To demonstrate its effectiveness in navigating to peripheral small size lung cancer lesions, we performed laboratory tests or a realistic lung airway model. The preliminary tests of a novel medical robot using a complex lung airway model proved that our catheter driving robotic system is working as designed and allows navigation, through a complex 3D channels structure like the bronchial tree, in both manipulator and robotic modes without fluoroscopy scanning. The robotic system is more precise and stable, and can avoid patient injury and instrument damage due to accidental impact with the airway wall. Because it could be controlled from a different room via the software platform, using this robotic system can drastically reduce radiation exposure of the patient and totally avoid the exposure of the doctor. Another benefit of the proposed robotic system is that it uses currently available catheters in which a reusable electromagnetic guide wire is temporarily inserted to guide the tip of the catheter towards hard to reach targets. After the target is confirmed, the sensor can be retracted and the catheter can be used for its routine function such as biopsy collection. Future development will include placement of a force sensor at the tip of the catheter to “feel” the wall and adapt the speed of insertion in order to avoid wall damage and an improved algorithm to increase the speed in the automatic mode.

Impact strength and morphological properties of Kenaf/glass fibre/polyester hybrid composite for attenuator application

Automobile attenuator component is a part of the frontal vehicle assembly which is used to absorb energy during the crash or accidental impact. Impact attenuator is considered as a capable protective device that is fixed right behind the bumper component of the car or vehicle. The materials used for the attenuator component are generally made of aluminium, steel and metal alloys. In the present days, due to hazardous environmental pollutions and carbon emission effects, synthetic and conventional materials are being replaced with natural fibres such as jute, sisal, kenaf etc. Natural fibres are widely used in polymer composites for automotive applications because of their lightweight, higher stiffness, and much stronger than bulk existing materials, and also quite good energy absorption characteristics comparable with metallic materials. This paper highlights the potential of natural fibre along with synthetic fibre reinforced polymer composites used in the automotive applications for crash energy absorption. A new technique such as vacuum infusion method was used to prepare the hybrid composites samples; pure polyester (control), Kenaf/Polyester Composite (KPC), Kenaf/Glass Fibre Polyester Composite (KGPC) and Kenaf/Glass Polyester Hybrid Composite with 6% NaOH treatment (KGPC-t) then followed by an experimental investigation on the effect of kenaf fibre on impact strength and energy absorption characteristics of kenaf/glass fibre/polyester hybrid composite material. Charpy impact strength kenaf/glass/polyester hybrid composite with NaOH treatment was increased by 3.88% than kenaf/glass/polyester hybrid composite without any treatment and 9.25% than kenaf/polyester composites without any treatment. In this study, SEM showed a visual graphical image of the fractured samples at 150X and 750X magnification has minimal pull-out and strong interfacial bonding between the fibres and the matrix.

Bearing Fault Diagnosis Based on Iterative 1.5-Dimensional Spectral Kurtosis

The key step of bearing fault diagnosis is to select a suitable resonance frequency band, so as to filter out interference components to the maximum extent and retain fault information in the resonance band. Kurtogram algorithm can locate the resonance frequency band well, which has been widely researched and applied in recent years, and has produced many derivative algorithms. The statistical indicators used by these methods to identify frequency band features are divided into time domain indicators and frequency domain indicators. Time domain indicators are more sensitive to a single accidental impact components, while frequency domain indicators are easily affected by harmonics in the time domain, that is, single or several frequency extremes in the frequency domain. In order to overcome the impact of non-periodic transient impulse components and modulation harmonic components, this article proposes a new method. This method uses wavelet packet transform (WPT) to divide the frequency band plane, and adopts 3 iterations 1.5-dimensional spectrum (1.5D spectrum) method, which can eliminate the impulse interference that has no coupling relationship in the time domain and frequency domain. Based on the above process, the $\text{K}_{\mathrm {I-1.5D}}$ gram method is constructed, which can realize more accurate positioning of the fault information. Finally, through simulated and experimental analysis, the effectiveness of the proposed method is verified.

Damage Detection and Decreased Load-Carrying Capacity Assessment of a Vertical-Lift Steel Truss Bridge

AbstractOver a bridge’s service life, physical damage, such as material deterioration, accidental impact, and overloading, can decrease its load-carrying capacity. To assess the integrity and servi...