Maximum Deformation Depth Research Articles

Математический расчет и значение коэффициента восстановления формы грудной клетки при планировании торакопластики врожденной воронкообразной деформации грудной клетки

Актуальность. Врожденная воронкообразная деформация грудной клетки характеризуется разным по глубине и ширине западением грудины и передних отделов ребер. Формообразование, его прогнозирование, расчет деформированного состояния грудной клетки и их изучение при планировании торакопластики по D. Nuss по поводу этой патологии является важной проблемой ортопедии и торакальной хирургии. Цель работы — расчет коэффициента восстановления формы грудной клетки путем соотношения глубины воронкообразной деформации и размера грудной клетки во фронтальной плоскости до и после математического моделирования торакопластики по D. Nuss. Материалы и методы. Для оценки перемещений ребер в зависимости от глубины деформации грудной клетки h были построены две модели. Первая модель представляет собой плоскую раму на опорах, элементы которой состоят из хрящевых частей ребер и грудины. Для данной модели определялась зависимость усилия F, которое необходимо для исправления глубины деформации грудной клетки. Вторая модель представляет собой изогнутый стержень, моделирующий ребро, к одному из концов которого приложена опорная нагрузка, вычисленная при анализе первой модели. Для данной модели определялось перемещение точки фиксации пластины под действием заданного усилия. Для получения более точных результатов были проведены исследования методом конечных элементов на модели грудной клетки. Результаты. Моделировалась коррекция глубины воронкообразной деформации без фиксации пластины к ребрам. Была проведена оценка перемещений участков ребер в месте фиксации пластины при разной глубине воронкообразной деформации грудной клетки: h = 2–5 см. Анализ результатов расчета показал, что после коррекции глубины деформации грудной клетки происходит уменьшение ее размера во фронтальной плоскости. Так, при максимальной глубине деформации h = 5 см отклонение участков ребер в месте фиксации пластины произошло на 2,4 см. Выводы. Установлена зависимость между глубиной воронкообразной деформации и размером грудной клетки во фронтальной плоскости при моделировании новообразованной формы грудной клетки при торакопластике по D. Nuss. Математически рассчитан коэффициент восстановления формы грудной клетки, который составляет 2 (2∆=h), где h — глубина воронкообразной деформации. Практическое значение коэффициента заключается в том, что при планировании торакопластики и придании формы пластине расстояние между ее латеральными концами, которые соответствуют форме грудной клетки и прилегают к ребрам, перед коррекцией воронкообразной деформации необходимо уменьшить на 1/2 h, где h — глубина воронкообразной деформации, для полноценного прилегания к ребрам в послеоперационном периоде.

Energy-dispersive X-ray micro Laue diffraction on a bent gold nanowire.

This article reports on energy-dispersive micro Laue (µLaue) diffraction of an individual gold nanowire that was mechanically deformed in three-point bending geometry using an atomic force microscope. The nanowire deformation was investigated by scanning the focused polychromatic X-ray beam along the nanowire and recording µLaue diffraction patterns using an energy-sensitive pnCCD detector that permits measurement of the angular positions of the Laue spots and the energies of the diffracted X-rays simultaneously. The plastic deformation of the nanowire was shown by a bending of up to 3.0 ± 0.1°, a torsion of up to 0.3 ± 0.1° and a maximum deformation depth of 80 ± 5 nm close to the position where the mechanical load was applied. In addition, extended Laue spots in the vicinity of one of the clamping points indicated the storage of geometrically necessary dislocations with a density of 7.5 × 1013 m-2. While µLaue diffraction with a non-energy-sensitive detector only gives access to the deviatoric strain, the energy sensitivity of the employed pnCCD offers absolute strain measurements with a resolution of 1%. Here, the residual strain after complete unloading of the nanowire amounted to maximum tensile and compressive strains of the order of +1.2 and -3%, which is comparable to the actual resolution limit. The combination of white-beam µLaue diffraction using an energy-sensitive pixel detector with nano-mechanical testing opens up new possibilities for the study of mechanical behavior at the nanoscale.

Wave-induced seafloor instabilities in the subaqueous Yellow River Delta—initiation and process of sediment failure

Submarine sediment failures or landslides triggered by storm waves in river delta areas pose a significant risk to coastal infrastructure. Due to the limitations of in situ monitoring technology, existing investigations are mostly carried out with geophysical techniques to provide some basic characteristics (e.g. location, size, runout distance, volume, and potential triggers) of existing submarine landslides. However, it is of equal importance to identify the starting criterion and the in situ evolutionary process of the initial stage of seafloor instabilities—sediment failure, which naturally relies heavily on long-term field observations. A field monitoring system was developed for observing sediment failure, which successfully recorded the wave-induced seabed deformation in the subaqueous Yellow River Delta for the first time. Once sediment failure is initiated, the shallow soil undergoes periodic and reciprocating oscillations under alternating action of wave crests and troughs. The evolution of the maximum deformation depth interface moves from shallow to deep, and then migrates upward from deep to shallow layers (the shallow-deep-shallow pattern), which indicates a stability recovery process following the wave-induced seabed failure, and these processes were found to occur multiple times within one storm event. Laboratory wave flume experimental results reproduced and verified the field observations, while also providing pore pressure data which explains the initiation of sediment failure and the deformation process. Finally, a development pattern of the seafloor instabilities in the subaqueous Yellow River Delta is proposed. The in situ observation methods proposed and the knowledge acquired by field monitoring and flume testing could benefit the investigation of costal seafloor instabilities.

Two-stage ball milling of recycled machining chips to create an alternative feedstock powder for metal additive manufacturing

To explore alternative and sustainable feedstock production for metal additive manufacturing, stainless steel powders were fabricated from recycled machining chips by ball milling. To achieve the desirable powder characteristics for additive manufacturing, the effect of ball size on the powder morphology change and particle size reduction was investigated through both theoretical analysis on the maximum deformation depth in the powder during ball milling and extensive experimental work. The modeling results suggest that large balls (diameter = 20 mm) efficiently break up machining chips to coarse powder particles while small balls (diameter = 6 mm) effectively modify the powder morphology to near-spherical. Therefore, a two-stage ball milling approach, i.e., using large balls at the initial stage of milling followed by a second stage of milling with small balls, was proposed in experiments and successfully converted machining chips to powders with near-spherical shape and particle sizes ranged from 38 to 150 μm. In addition, the nanoindentation hardness of the ball milled powder created from machining chips is 56% higher than the gas atomized powder. To verify the usability of the ball milled powder created from recycled machining chips in additive manufacturing, single tracks have been successfully deposited via laser engineered net shaping.

Laser High-Speed Impact Composite Forming of Aluminum/Aluminum

Based on the laser-driven flyer micro forming and laser high-speed impact welding, this paper put forward the laser high-speed impact synchronous welding and forming new process, and builds the compound welding experiment platform. The three-dimensional deep field digital microscope of KEYENCE VHX-1000C was used to measure the surface morphology and the maximum deformation depth of the welding and formingsamples. By observing the surface morphology of the sample, it was found that strong plastic deformation occurred on the surface of the materials and well reproduced the shape of the mold. When the laser energy was below 4.5J, the maximum deformation depth of the samples increased with the laser energy. However, the maximum deformation depth decreased due to the spring back phenomenon when the laser energy was larger than 4.5J. The Axio CSM 700 confocal microscope was used to measure the morphology of the welding interface. The cross profile of the welding interface showed that most regions had been welded and the welding interface was nearly flat.

Axially Movable Electromagnetic Forming System for Large-Scale Metallic Sheet

How to generate strong enough electromagnetic forces in the electromagnetic forming process is an important issue for sheet forming. For this purpose, an axially movable electromagnetic forming system was designed, fabricated, and tested. To validate the effectiveness of the system, a series of experiments on the forming of AA1060 with a diameter of 440 mm and a thickness of 3 mm has been carried out. A pulsed magnet with an inner diameter of 100 mm and an outer diameter of 200 mm was used to drive the sheet. A capacitor bank power supply (200 kJ/25 kV/640 μF) has been used to energize the coil. The experimental results have shown that the maximum deformation depth of the workpiece is only about 90 mm when the forming coil was fixed after three discharges. This value can be greatly increased to 130 mm by the use of the proposed forming method in which the distance between the coil and the deformed workpiece was decreased in each discharge process. Meanwhile, the geometric accuracy between the final deformed workpiece and die is less than 3 mm according to the three-dimensional scanning analysis.

Forming Properties of a Microscale Laser Dynamic Flexible Forming Technique

Microscale laser dynamic flexible forming (µLDFF) is a novel micro-forming process. Laser-induced shockwaves act on the soft punch to deform the metal foils. In this article, the forming properties of the µLDFF process are studied from four angles, namely, the maximum deformation depth, accuracy, thickness thinning ratio, and surface quality. The maximum deformation depth of the samples formed under different laser energies was measured. The 2D profiles of the workpieces were measured to study the accuracy. The results show that the deformed samples replicated the mold features well. The cold-mounted technique was used to measure the thickness of the deformed metal foils along the cross section and to discuss the thickness thinning ratio. The results show that µLDFF can reduce localized necking and stress concentrations effectively. The surface roughness was characterized to study the surface quality of the workpieces, and the results indicated that the deterioration of the formed surface was weakened during µLDFF. The advantages of the ultrahigh strain rate and soft punch are both presented in the µLDFF process, which is favorable for fabricating micro components.

Identifying the tool-tissue force in robotic laparoscopic surgery using neuro-evolutionary fuzzy systems and a synchronous self-learning hyper level supervisor

In this paper, two different hybrid intelligent systems are applied to develop practical soft identifiers for modeling the tool-tissue force as well as the resulted maximum local stress in laparoscopic surgery. To conduct the system identification process, a 2D model of an in vivo porcine liver was built for different probing tasks. Based on the simulation, three different geometric features, i.e. maximum deformation angle, maximum deformation depth and width of displacement constraint of the reconstructed shape of the deformed body are extracted. Thereafter, two different fuzzy inference paradigms are proposed for the identification task. The first identifier is an adaptive co-evolutionary fuzzy inference system (ACFIS) which takes advantage of bio-inspired supervisors to be reconciled to the characteristics of the problem at hand. To learn the fuzzy machine, the authors propose a co-evolutionary technique which uses a modified optimizer called scale factor local search differential evolution (SFLSDE) as the core metaheuristic. The concept of co-evolving is implemented through a consequential optimization procedure in which the degree of optimality of the ACFIS architecture is evaluated by sharing the characteristics of both antecedent and consequent parts between two different SFLSDEs. The second identifier is an adaptive neuro-fuzzy inference system (ANFIS) which is based on the use of some well-known neuro computing concepts, i.e. back-propagation learning and synaptic nodal computing, for tuning the construction of the fuzzy identifier. The two proposed techniques are used to identify the force and maximum local stress of tool-tissue. Based on the experiments, the authors have observed that each of the identifiers have their own advantages and disadvantages. However, both ACFIS and ANFIS succeed to identify the model outputs precisely. Moreover, to ascertain the veracity of the derived systems, the authors adopt a Pareto-based hyper-level heuristic approach called synchronous self-learning Pareto strategy (SSLPS). This technique provides the authors with good information regarding the optimum controlling parameters of both ACFIS and ANFIS identifiers.

Acquisition and Analysis on 3D Deformation of Windshield Glass in Vehicle-Pedestrian Accident

A method based on the 3D laser scanning is proposed for obtaining and analyzing the windshield's deformation in vehicle-pedestrian accident. With an actual traffic accident of vehicle-pedestrian collision taken for example, point cloud data of windshield’s deformation is scanned by EXAScan 3D laser scanner and the deformed 3D NURBS surface is obtained after fitting process. Based on the discussion about characteristics of curved surface of the vehicle’s front windshield and the principle of continuous curvature, this paper conducts a surface fitting with cubic non-uniform spline according to geometric information of grid surface around the deformation zone, and obtains the pre-deformed surface of windshield by sampling with spline curve. Compared with the pre-deformed surface of vehicle’s windshield, the maximum deformation depth is 48.509mm and its area is 0.3816m2on the right side, while the maximum deformation depth is 36.341mm and its area is 0.2529m2on the left side. The application results in actual traffic accident show that this method can be used to obtain 3D deformation information of overall impact area, which provide a new method for accurately inspecting the windshield’s deformation in vehicle-pedestrian accident. This method also provides a new research idea for quantitative saving the evidence in permanent, and it also has a great value in accident analysis and reconstruction.

Use of reinforced rigid polyurethane foam for blast hazard mitigation

This article presents the development of a cost-effective lightweight protection technique for explosives transporting container and storage facilities employing surface-mounted Rigid Polyurethane Foam (RPF) plates. Different RPF specimens were prepared with different densities and sand particle reinforcement ratios ranging between 0% (unreinforced) and 30%. Mechanical properties characterization was conducted to optimize an RPF formulation to be tested under blast loading using different experimental techniques. Explosive scaling laws were utilized to relate indoor blast test results (performed with small explosive charges) to real-life blast scenarios. Small RDX explosive charges were placed and detonated inside RPF specimens to correlate the size of the resulting cavity to the explosive charge weight and the RPF density. Another set of experiments were conducted to evaluate the maximum deformation depth of lead witness plates resulting from blast waves. In these latter experiments, explosive charges were mounted on the free surface of RPF plates. In general, test results demonstrated the capability of reinforced RPF as a light weight cost-effective technique to mitigate blast load hazard.

Influence of Carburization on Mechanical Behaviors of NiTiCu Alloy under Dynamic Impact Loading

The mechanical behaviors of bare and carburized NiTiCu specimens under dynamic impact loading were investigated using a home-built impact testing system. The contact force was measured with piezoelectric force sensor and digital signal processing system in real time during impact process. Predicted instantaneous velocity and displacement formula were presented. The results show that the maximum deformation depth of carburized specimens was less than that of bare specimens, and the carburization process can increase absorbed energy and cushion effect to impact of specimens during impact process. The decrease of deformation depth and increase of absorbed energy can reduce the contact force and materials damage of specimens during impact process.

Influencing factors on the injury severity of restrained front seat occupants in car-to-car head-on collisions

The results of 319 cases of belt-restrained front seat car occupants (234 drivers and 85 passengers) from 241 vehicles in car-to-car head-on collisions were examined. Ninety-five occupants were uninjured, 195 sustained a total injury severity of Maximum Abbreviated Injury Score (MAIS) 1–3 and 29, MAIS 4–6. There were 27 fatalities, and the main causes of death were polytrauma and hemorrhage. The main factors influencing occupant injury severity were: the energy equivalent speed (EES); the change of velocity (delta v); the maximum deformation depth; and the collision angle. With an EES > 50 km/h fatal injuries can be expected, and above 60 km/h no occupant remained uninjured. The results of a multivariate analysis were: EES influenced the injury severity at all body locations except the spinal cord; occupant position effected only head injury severity, with drivers being more severely injured; occupant age influenced the injury severity at the thorax, abdomen, and extremities and MAIS as well. Age was a further factor influencing injury severity, e.g. with an EES of 50 km/h the probability of being fatally injured was 30%–45% higher for occupants over 59 years than those under 20.