Deformation Depth Research Articles

Визначення дистанції та обставин пострілу у сучасних умовах

The article is devoted to the study of the possibility, through the study of the presence, location and shape of traces of additional factors of the shot, to find out the distance and circumstances of the incident. Today, against the backdrop of military aggression and crimes against the life and health of people, both military and civilian, these data are essential to collect evidence of the insidious actions of the enemy on the territory of sovereign Ukraine. In the course of the work, an analysis of the special literature on the methods of studying gunshot wounds and determining the distances of a shot was carried out to establish the circumstances of the incident at the scene of the incident and during the forensic medical examination. These are the works of A.I. Gerasimenko (1997), V.I. Kononenko (2003), A.V. Filipchuk (2010), A.A. Babanin, V.D. Mishalov, A.V. Belovitsky, A.Yu Skrebkova (2012), A.Kh. Zavalnyuk (2016) and others. The term “additional shot factors” or “shot related factors” means everything that flies out of the bore of a firearm during a shot, except for a bullet. The author gives signs of gunshot injuries from different shot distances: close (dense and loose), close and not close. The characteristics of the wound when fired through an obstacle are given, determined by the presence of deposits of foreign particles (fragments of the obstacle) around the entrance wound and in its depth and signs of deformation of the firearm, the elongated shape of the entrance wound or the multiple (debris-ball) nature of the wound with a radial direction, as well as a very large amount of damage due to secondary projectiles. Damages on various materials of clothing are analyzed when shots are close, close and not close distances. The features of soot deposition in the Vinogradov phenomenon are considered. Therefore, it should be noted that additional factors of the shot determine its distance, and the presence, location and shape of their marks on clothing and body helps to clarify the circumstances of the incident. Awareness in these matters makes it easier to conduct an inspection of the scene and makes it possible to more accurately provide forensic medical examination questions in the case of gunshot injuries.

Визначення параметрів та ефективність роботи додаткових робочих органів глибокорозпушувачів

The article presents an overview and analysis of existing additional operating parts of combined deep tillers of serial machines. It was established that the issue of assessing the effectiveness of additional operating parts of deep tillers and the search for their rational structural and technological parameters is insufficiently studied and needs practical solution. The most versatile operating part for high-quality work of deep tillers can be a paired toothed roller. Having studied its design parameters and operating modes, it is possible to get clear recommendations regarding its use. An improved design of the Tandem Spiked toothed roller type with mechanical adjustment is proposed, as such rollers have a much simpler shape of teeth and a smaller cross-section of each tooth. The dependences for the calculation of certain design parameters of the roller, namely its diameter, length and coefficient of volume deformation of the soil, are given based on the fact that the roller performs two functions – compaction of the lower layers of the soil and crushing of clods and intensive mixing of the upper horizons. To determine the rolling force on the soil surface, we use the relationship that includes the weight of the roller, the volume deformation coefficient of the soil, the grip width of the roller and its diameter. Field studies to assess the efficiency of paired toothed rollers ere carried out. For the effective operation of combined deep tillers of the soil, it is necessary to use additional operating parts, which should additionally grind large particles and partially mix and distribute plant residues. It is most expedient to use paired toothed rollers with mechanical adjustment as additional operating parts under difficult working conditions. At the stage of substantiating the design parameters of paired toothed rollers, it is enough to take into account the required angle of the soil roller's girth and the average value of the soil deformation depth. This will allow getting actual value of the working diameter of the roller and calculate the force of the roller rolling over the soil surface. During field studies of the operation of combined deep tillers with a paired toothed roller, it was established that when working with two toothed rollers at a working speed of 7.2...8.2 km/h, the qualitative indicator of soil crushing is at the level of 70...75%, which significantly exceeds the qualitative indicators of the work of foreign machines of a similar design under the same operating conditions.

Load dependent microstructural evolution in an as-cast 26% Cr high chromium cast iron during unlubricated sliding

In the current study, an as-cast 26% Cr high chromium cast iron (HCCI) alloy was subjected to dry-sliding linear wear tests, under different loads. The loads were selected based on analytically computing the critical load (PC) i.e., the load necessary to induce plastic deformation. The PC was calculated to be 15 N and accordingly, a sub-critical load (5 N) and an over-critical load (20 N) were chosen. The influence of increasing the load during the wear test was investigated in terms of the matrix microstructural behaviour and its ability to support the surrounding carbides. The morphological aspects of the wear tracks, and the deformed matrix microstructure adjacent and underneath the track was analysed by confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM), respectively. No evidence of plastic deformation of the matrix was observed below PC. On the contrary, at loads equal to and higher than PC, the austenitic matrix plastically deformed as evidenced by the presence of slip bands. Electron backscattered diffraction (EBSD) measurements in terms of grain reference orientation deviation, and micro-Vickers hardness of the austenitic matrix indicated a deformation depth of about 40 µm at the maximum applied load of 20 N. The active wear mechanisms during sliding were a combination of both adhesive and abrasive wear, although increasing the load shifted the dominant mechanism towards abrasion. This was primarily attributable to the increased propensity for carbide cracking and fracturing, combined with the inability of the hardened austenitic matrix surface and sub-surface to adequately support the broken carbide fragments. Moreover, the shift in the dominant wear mechanism was also reflected in the wear volume and subsequently, the wear rate.

Non-destructive measurement of grinding-induced deformation-depth using grazing incidence X-ray diffraction technique

The present research work proposes a non-destructive methodology to detect and measure subsurface deformation using Grazing incidence X-ray diffraction (Gi-XRD). The FWHM of the XRD peak that indicates the degree of plastic deformation was measured at different X-ray penetration depths by changing the angle of incidence during Gi-XRD. However, these FWHM values do not represent the actual FWHM at a particular depth because it also captures the effect of the top layers. Therefore, the FWHM values were further analysed to get the actual FWHM for a particular penetration depth and correlated with the deformation depth. The non-destructively measured deformed layer thickness was verified against the results of the metallographic study and a deviation of around 1.2 μm was recorded.

A Method for Calculating the Velocity of Corner-to-Corner Rear-End Collisions of Vehicles Based on Collision Deformation Analysis

To improve the efficiency of solving vehicle collision velocity and provide sufficient evidence for the identification of accident responsibility, we proposed a method combining the momentum equation and finite element simulation. We built a finite element simulation model of a vehicle where multiple collision simulation experiments were carried out, and studied the calculation method of collision deformation. After fitting and analyzing the simulated deformation data of an accident vehicle under different velocities through collision simulation experiments, a relationship model between collision velocity and deformation was established, and a method to solve the collision velocity was proposed by combing the existing two-dimensional collision momentum equation of the vehicle. For actual collision cases, the proposed velocity solution method and the simulation software were used for reconstruction analyses, respectively, and the results of the instantaneous contact velocity of vehicle collision were compared. It was found that the velocity calculation results obtained using the two methods above were in good agreement; the shape and depth of the simulated deformation were consistent with the actual deformation of the vehicle.

The influence of cementite spheroidizing duration on the microstructure and sliding wear response of grey cast iron against AISI 4330

The present study investigates the sliding wear properties of G350 grey cast iron following various spheroidizing annealing durations. The annealed samples were used as pins in sliding wear tests against AISI 4330 discs. Most testing combinations resulted in mild wear with little matrix damage to the cast iron pin or AISI 4330 disc. A transition to severe wear was observed for the highest load and longest annealing times where the overly spheroidized and ferritized cast iron matrix deformed significantly, prohibited beneficial oxidative wear from occurring, and thus damaged its disc counterpart. The depth of subsurface deformation increased with annealing time but not load. Instead, the depth peaked at 4 kg applied load for each condition due to the spallation of the affected surface layer at the higher load.

Experimental and Numerical Analysis of the Depth of the Strengthened Layer on Shafts Resulting from Roller Burnishing with Roller Braking Moment.

The article presents the results of investigations into the depth of the plastically deformed surface layer in the roller burnishing process. The investigation was carried out in order to obtain information on the dependence relationship between the depth of plastic deformation, the pressure on the roller and the braking torque. The research was carried out according to the original method developed by the authors, in which the depth of plastic deformation is increased by applying a braking torque to the burnishing roller. In this method, it is possible to significantly increase (up to 20%) the depth of plastic deformation of the surface layer. The tests were carried out on a specially designed device on which the braking torque can be set and the force of the rolling resistance of the roller during burnishing can be measured. The tests were carried out on specimens made of C45 heat-treatable carbon steel. The dependence of the depth of the plastically deformed surface layer was determined for a given pressure force and variable braking moments. The depth of the plastically deformed layer was measured on the deformed end face of the ring-shaped samples. The microhardness in the sample cross-section and the evolution of the microstructure were both analysed.

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.

Системний аналіз процесів тертя та зношування при застосуванні фулеренових композицій в мастильних матеріалах

The system-structural approach in researches of processes of friction and wear at application of fullerene compositions in lubricants is proved in the work. It is proposed to use a multilevel approach to study and model the processes of deformation of the surface layers of movable and fixed triboelements and the formation on energy-activated surfaces of wear-resistant structures containing fullerene molecules. The essence of the approach is to use multi-scale research methods to build mathematical models within a single research structure. Due to the fact that tribosystems differ in the integrity of the interconnected elements included in them, it is assumed that all processes occur at three hierarchical levels. At this level, they interact with each other and exchange energy and matter. Input and output flows in studies of tribosystems are formulated. It is shown that the input streams include design parameters of the tribosystem, technological parameters, operating parameters. These parameters form the flow of matter, energy and information, which is the input effect on the tribosystem. The output flow from the tribosystem are the parameters: volumetric wear rate I, dimension m3/hour; friction losses, which are estimated by the coefficient of friction f, dimensionless quantity. The output stream is the information flow of the tribosystem. When solving contact problems, this allows to take into account not only the level of stresses, but also the speed of deformation in the materials of the surface layers, as well as the depth of deformation, which in the models will take into account the volume of deformed material.Depending on the tasks and requirements for their solution, the use of different methodological approaches for modeling is justified. It is shown that the application of mathematical models in the modeling of tribological processes depends on the correct choice of technical constraints that determine the range of optimal solutions

Finite element investigation of cutting performance of Cr/W-DLC/DLC composite coated cutting tool

DLC has been applied as coating material in the machining of difficult-to-cut materials, and shows a good cutting performance. In this study, Cr/W-DLC/DLC-coated tools were compared with other three kinds of coated tools (TiC-, TiAlN-, Al2O3-) to investigate the cutting performance in the machining of Al–Si alloy. The influence of Cr/W-DLC/DLC-coated tools on the cutting performance under different cutting speeds was studied. Cutting force, cutting temperature, heat partition coefficient, cutting deformation rate, plastic deformation of machined surface, the interface temperature, and stress were investigated numerically with the aid of finite element method (FEM). Actual cutting experiments were carried out to verify the FEM models by means of the cutting force and cutting temperature measurement. The investigation results show that Cr/W-DLC/DLC-coated tool had the best cutting performance among these four kinds of coated tools. With the increasing of cutting speeds, cutting force and cutting temperature showed an increase trend, while the plastic deformation depth of machined surface and heat partition into cutting tool all showed a decrease trend during the machining with Cr/W-DLC/DLC-coated tool. This investigation can provide the theory basis or technical guidance for the cutting practice with Cr/W-DLC/DLC-coated tools.

Determination of Horizontal In-Situ Stress Profiles and Rock Deformation Moduli in Karamay Basin Using a Multiobjective Optimization Technique

Summary We introduce a quick and cost-effective method of estimating horizontal in-situ stress profiles and rock elastic moduli vs. depth from geophysical logs taken in vertical well sections. A multiobjective optimization approach finds the optimum solution for the inversion of in-situ stresses and the rock mechanical parameters from elastic borehole deformations measured by the commonly available four-arm caliper tools. The four-arm caliper log responses also permit quality control (QC) of input and identification and classification of borehole sections that display breakouts and sloughing. The method is applied in the estimation of horizontal in-situ stress profiles and rock deformation moduli vs. depth in Karamay Basin, Northwestern China. The results have demonstrated good agreement with available field in-situ stress measurements, indicating promising broader applications of the method.

Comprehensive Geophysical Study at Wabar Crater, Rub Al‐Khali Desert, Saudi Arabia

AbstractInterest in impact craters on the earth's surface has increased worldwide and is being investigated by using remote sensing, geological, boreholes, geophysical, and laboratory measurements. These measurements are used to build dynamic models to study crater formation. In this work, the near‐crater sediments at the young Wabar crater field in Saudi Arabia have been investigated using magnetic, transient electromagnetic (TEM), seismic, and ground‐penetrating radar (GPR) methods. The main objectives of this research were to (a) explore the possibility of any remnant major pieces of the meteorite, (b) investigate the meteoroid direction, and (c) map the deformational structures associated with the meteorite impact. Our results show five different magnetic anomaly types and three layers in the subsurface. The maximum depth of deformation due to the impact of the meteorite is about 25 m as shown by the seismic travel time tomogram, the quasi‐2D TEM, and the 3D GPR model. TEM survey confirmed the geometrical characteristics of the major crater and located another small crater (known as Philby‐A). The magnetic survey shows no evidence of any remnant major pieces of the meteorite; however, it was used to trace ejecta material containing highly dilute magnetic material. The magnetic carrier is most likely spheres of metal incorporated in the black/green glasses. During the expedition, many small pieces of the meteoroid were found and collected for further geochemical analysis. Based on the geophysical findings, the meteorite direction was found to be from north to south.

ОБЕСПЕЧЕНИЕ КАЧЕСТВЕННО-ТОЧНОСТНЫХ ХАРАКТЕРИСТИК ПРИ ВОССТАНОВЛЕНИИ ДЕТАЛЕЙ АВТОТРАНСПОРТА

One of the most common reasons for the failure of hydraulic drive systems for agricultural machinery is the working fluid leak in the contact points of the rubbing surfaces of hydraulic blocks. The application of composite coatings based on chromium on the contacting surfaces allows you to restore the defect in the shape of the part caused by wear, as well as reduce the friction coefficient at the contact points, which positively affects the wear resistance of the part. (Research purpose) The research purpose is in developing technologies for restoring parts of agricultural machinery with predetermined operational properties. (Materials and methods) A servo valve, widely used in various hydraulic drive systems, was used as an experimental sample. Its working surface was restored with a composite coating applied by electroplating to increase the wear resistance of the servo valve. (Results and discussion) Authors conducted a series of direct measurements under the same conditions. The article presents the de-pendence of the microhardness on the parameters of the electrolysis mode and the thickness of the applied coating using the method of least squares. The nature of changes in microhardness and residual stresses was evaluated to determine the quality of the coatings. The article presents the dependences of these indicators on various control parameters (current density, temperature, tool pressure). The equations of the regression of the main qualitative and accuracy characteristics of the parts were deter-mined using the apparatus of the theory of experimental planning. (Conclusions) The article presents the method for predicting coatings of a given quality, taking into ac-count the influence of the current density and the temperature of the electrolyte during electrolysis on the nature of the precipitation obtained. The influence of the tool pressure on the depth of deformation of the formed layers was estimated. This approach allows us to evaluate the nature of the stress distribution in the formed coating and the quality of the restored parts.

A complex rockslide developed from a deep-seated toppling failure in the upper Lancang River, Southwest China

A large-scale rockslide, developed from a deep-seated toppling failure, occurred in October 2018 following reservoir impoundment in the upper Lancang River, Southwest China. The evolution of this slope failure was investigated to reveal the instability mechanism of the rockslide after impoundment. Electron spin resonance (ESR) dating was used to determine the formation period of the toppling failure. Detailed field investigations, including joint measurements and surface, borehole and adit surveys, revealed the surface and subsurface features of the deformed rock masses. The Universal Distinct Element Code (UDEC) was used to simulate the evolutionary process of the slope failure. The results show that the toppling deformation rate accelerated with river downcutting and decreased after the modern valley formed. After reservoir impoundment, the mode of slope deformation transformed from creep toppling to rapid sliding. The sliding progressed upslope due to shear failure at the slope toe. In addition, the results of a series of simulations show that the action of tectonic stress can significantly increase the depth of toppling deformation. The investigation results imply that the evolution of the slope failure included five stages: initial deformation, accelerating deformation, creep deformation, formation of a throughgoing sliding surface and failure. The first three stages were dominated by toppling, whereas sliding dominated the latter two stages. Toppling was induced by river downcutting and promoted by the effects of tectonic stress and gravity. Reservoir impoundment promoted sliding at the slope toe, which induced upslope propagation of sliding above the toppling hinge surface. Once the slip zone coalesced with the shear failure surface at the front of the slope, the main rockslide occurred.

Laser-induction hybrid cladding of different coatings on rail surface: Microstructure, wear properties and contact fatigue behaviors

In this paper, Ni-Cr-Fe, 17-4PH and 18Ni300 alloy coating were deposited on the rail surface by laser-induction hybrid cladding (LIHC), respectively. The microstructure, microhardness of different coatings, and their influences on the wear properties and contact fatigue behaviors of rails were studied systematically. Results indicate that the as-deposited Ni-Cr-Fe coating is constituted of the dendrite structure, and the as-deposited 17-4PH and 18Ni300 coating mainly consist of the lath martensite structure. The microstructure and microhardness of Ni-Cr-Fe coating are little influenced by the in-situ thermal cycling in LIHC process, whereas the grain size and precipitates’ content in 17-4PH and 18Ni300 coating are affected significantly, making the microhardness therein increased along the depth direction. Compared with the untreated rail, the wear rate and plastic deformation (PD) depth of rails with 17-4PH and 18Ni300 coating are both decreased significantly, while the contact surface damage is alleviated simultaneously. Especially for that with 18Ni300 coating, the decreased proportions are as high as 40.2% (mass wear rate), 60.1–81.2% (dimensional wear rate) and 78.7% (plastic deformation depth), respectively. By contrast, the wear rate of rail with Ni-Cr-Fe coating is increased conversely than that of the untreated rail although its microhardness is 32% higher. Therefore, the LIHC deposited 18Ni300 coating is a competitive choice for repairing the rail in engineering.

Improving the accuracy of calculating the speed of movement at the time of an accident in collisions with incomplete overlap of a part of the car

Introduction. Driving at a speed exceeding the permitted and average speed of traffic flow often leads to a collision of vehicles with other road users or with elements of the arrangement of highways. As a result, it is necessary to establish whether the fact of this violation of the traffic rules, which led to the occurrence of an emergency-dangerous road traffic situation. The methods used to calculate the speed of vehicles based on the resulting deformations are quite accurate, but this fact is true in conditions of complete overlap (impact across the entire width of the front, rear or side parts of the body). But there is a scientific task of developing a methodology according to which an expert or investigator will be able to calculate the average statistical value of measuring the depth of deformation of a vehicle for a specific road traffic situation.Materials and methods. The paper proposes a method for evaluating the possibility of using the data available to the expert for calculation by introducing the coefficient of variation of the depth of penetration. With the help of the coefficient of variation, the specialist has a tool for selecting and ignoring individual measurements of the depth of penetration, depending on the degree of overlap and on the ‘spread’ of the deformation values.Conclusions. After studying a number of collisions with incomplete overlap and excluding the ‘extra’ values of penetration, the speed equivalent to the energy cost for the development of residual deformations and errors (the difference between the true collision speed and the established one without taking into account the ‘falling out’ values of deformations) was calculated and it was found that the use of the algorithm taking into account the coefficient of variation led to sufficiently accurate calculation results.Discussions. The proposed methodology regulates the use of the coefficient of variation as a criterion for the admissibility of the use of source data to determine the quality of the final result of the calculation. This mathematical device is applicable to all collisions, but is especially relevant when studying collisions with incomplete overlap of any part of the car body.

Microstructural evolution and surface integrity of ultrasonic surface rolling in Ti6Al4V alloy

Ultrasonic surface rolling technology is a new mechanical surface treatment technology that can improve the surface integrity, increase the amplitude and depth of the residual compressive stress layer and improve the fatigue property of metal materials. In this paper, the effect of ultrasonic rolling on the surface layer's microstructure and properties of Ti6Al4V alloys is investigated. The microstructure, surface roughness, surface topography, microhardness and residual stress were used to characterise the surface-modified layer. Specimens treated by ultrasonic surface rolling obtained the smallest surface roughness (0.231 μm) and largest plastic deformation depth (304.38 μm), simultaneously, under sixteen processing stage numbers. The rule of surface compressive residual stress distribution had a similar tendency to the law of surface microhardness distribution. Furthermore, the grain size of the strengthened surface layer decreased, the texture type changed and the Schmidt factor increased compared with the matrix. The increase of microhardness and residual stress is due to grain refinement and dislocation strengthening.

Selected Aspects of Pavement Texture Influence on Tire Rolling Resistance

Tire rolling resistance has a significant influence on fuel consumption in cars and trucks and on CO2 emissions. Rolling resistance depends on the tire construction, pavement texture and stiffness, as well as environmental and traffic conditions. This article presents a pilot study on the impact of pavement texture on the rolling resistance of passenger car tires. Reasons why Mean Profile Depth is not a good descriptor of pavement characteristics from the point of view of rolling resistance are presented, and an experimental method which takes into account tire deformation on texture and partial enveloping is described. A method based on testing the volume and depth of tire tread deformation is also proposed.

A spectroscopic approach for rapid and simple serial number restoration on polyamide 6 parts of firearms: The use of video spectral comparator 8000.

Serial numbers have forensic value as they help to identify firearms. While the serial numbers are mostly stamped on the metal parts of firearms, the characters on polymer parts involve non-serial number information such as caliber, brand, model, or proof marks, which also serve for identification purposes. The forensic evidence indicates that the polymer frames of firearms bearing non-serial number information are obliterated through heating and scraping. Although the destructive restoration techniques for polymers are well-documented, there is little theoretical and practical knowledge regarding the non-destructive restoration techniques applied on polymers. In view of this gap, this study aims to devise a non-destructive spectral technique to recover the obliterated characters on Polyamide 6. Considering its wide use on polymers, the numbering is carried out by hot stamping and the numbers are defaced through heating, scraping, and hammering both superficially and deeply at varying depths. Herein, we focused on imitating the manual obliteration techniques used by criminals instead of the deepness-controlled techniques preferred by previous studies. The samples are then viewed under the UV and IR lights in the Video Spectral Comparator 8000 for the first time. The results suggest that spectral imaging provided restoration to a good extent after heating and scraping which made the characters invisible at a relatively low depth of deformation compared to hammering. The recovery of characters with this novel technique brings a new perspective forensic marks examination literature by producing quick, successful and reliable results and facilitating reexamination by not harming the sample.

Role of stress, slenderness and foliation on large anisotropic deformations at deep underground excavations

High stress concentrations around underground excavations can result in significant damage to deep hard-rock mines. These conditions can be the result of stopping activities, blasting, seismicity, or other mining activities. Large anisotropic deformation and excavation closure, especially under high-stress conditions, are expected if the excavation is located in a foliated or thin-bedded rock mass. In this research, the behaviour of excavations under deep and high-stress conditions was investigated and categorised. The main purpose was to enhance the existing knowledge of managing large anisotropic deformations and to help prepare suitable measures for handling such contingencies. Numerical simulations using the distinct element method (DEM) and model calibration were performed to reproduce the anisotropic deformation of an ore drive based on the collected field data. Then, the roles of key factors (i.e. stress ratio, slenderness ratio, foliation orientation, and foliation considering excavation orientation) on the large deformation and damage depth of the excavations were investigated. This study found that increasing both the stress ratio and slenderness ratio induced linear increases in wall closure and damage depth, whereas increasing the foliation angle first increases the deformation and damage depth and then reduces them both before and after 45°. The wall closure and damage thickness decreased with increasing orientation intercept. The deformation and damage levels were classified based on these factors.