Analysis of jumping/falling distance from a height

Bodies bounce - deflection of bodies following first ground impact after falls from height

Forensic examination of a scene where two bodies were found after a fall from a high-rise apartment building revealed a distinct tissue imprint resembling facial contours on the asphalt between the two bodies as well as a laceration on the back of the head and an abrasion on the forehead of one body. Tissue imprints located away from the positions of the bodies can indicate manipulation of the finding scene and injuries in opposing body regions at least two distinct blunt traumas. Initial assessment ruled out intermediate contacts with the building, pointing instead to a significant horizontal deflection of the bodies after the initial impact on the ground followed by a second impact. A review of the existing literature on falls from height was conducted, which provided limited information on the possibility of a body's deflection after fall from height. Detailed investigations into the biomechanical relevance of sequences following that impact are rare. In contrast, surveillance video footage from the presented case shows the deflection of the corpses by as much as 1.5 m after initial impact, followed by a second impact. In combination with the autopsy results this provided a good explanation for the unusual forensic findings and unique biomechanical insights. It demonstrates that, depending on various factors like the impacted body region, ground structure and height of fall, a body can be significantly deflected from the initial impact region, resulting in a second impact and sometimes forensically misleading injury patterns.

Slip and tilt: modeling falls over railings

Falls over railings are frequent case scenarios forensic experts are confronted with. An important issue is the differentiation of accidental and non-accidental falling scenarios. From a biomechanical point of view, this is a challenging task and should be addressed in a multifactorial approach. This work presents a simplified mechanical model in terms of a cranked rod that can be used in cases without relevant dynamic components in terms of pushing or jumping. If the anti-slip and the anti-tilt condition are violated, the possibility for a person to get over a railing should be assumed and investigated in more detail. Because our approach also involves uncertainties, the formulae should be understood to be part of a multifactorial approach. Numerical simulation, experimental reconstruction, injury pattern, and trace analysis can yield additional substantial connecting facts.

Characteristic analysis and fuzzy simulation of falls-from-height mechanics, and case studies

In this paper, methods for scientifically inferring the causes of the falls-from-height accidents, that is, the initial fall postures, and reconstructing the fall accident are presented. For this purpose, the general types of fall were subdivided into eight, and the characteristics of each fall type were analyzed. An initial posture estimation tool based on Fuzzy method was developed utilizing the massive amount of quantitative database that was constructed by repeating the simulation program for all types of falls. In addition, the initial conditions for each type were standardized with the experimental results and simulation data to reconstruct the fall behavior using the estimated fall accident type. The results of four carefully selected case studies were presented to verify the reliability and practicality of the developed fall analysis program and the reconstruction method.

Effect of Wind on Horizontal Displacement of Fatal Fall from a Height

The horizontal displacement of the human body resulting from fatal fall from a height is an important variable commonly used to inversely determine the cause or identify other forensic aspects of the fall. When examining the horizontal displacement, the wind effect is generally ignored. This technical note reports analytical modeling of the falling process, utilizing previous measurements of wind force acting on the human body, for determining the functional relationship between the wind speed and the horizontal displacement in the falling process. The result reveals that it does not take extremely rare wind conditions to cause a considerable shift of the human body, highlighting the importance to consider wind as a factor in investigations of fatal falls.

Forensic Application of Analytical Mechanics in Fatal Fall From a Height

Fatal fall from a height initiated with a swinging motion on the sagittal plane of the victim's body is examined. Method of analytical mechanics is adopted to establish the functional relations between the swinging angle of the body and the force needed to sustain the body until release, and the amount of the horizontal displacement that would occur after release. The analysis is applied to support an expert opinion presented in a criminal court in which two accused were convicted of murder for dropping a female victim from a bridge. The results indicate that it is unlikely for the body to locate as recorded by the police investigation report in the case. This study demonstrates that a straightforward mechanical analysis can be utilized to examine uncommon falling scenarios.

From military to civil loadings: Preliminary numerical-based thorax injury criteria investigations

Effects of the impact of a mechanical structure on the human body are of great interest in the understanding of body trauma. Experimental tests have led to first conclusions about the dangerousness of an impact observing impact forces or displacement time history with PMHS (Post Mortem human Subjects). They have allowed providing interesting data for the development and the validation of numerical biomechanical models. These models, widely used in the framework of automotive crashworthiness, have led to the development of numerical-based injury criteria and tolerance thresholds. The aim of this process is to improve the safety of mechanical structures in interaction with the body. In a military context, investigations both at experimental and numerical level are less successfully completed. For both military and civil frameworks, the literature list a number of numerical analysis trying to propose injury mechanisms, and tolerance thresholds based on biofidelic Finite Element (FE) models of different part of the human body. However the link between both frameworks is not obvious, since lots of parameters are different: great mass impacts at relatively low velocity for civil impacts (falls, automotive crashworthiness) and low mass at very high velocity for military loadings (ballistic, blast). In this study, different accident cases were investigated, and replicated with a previously developed and validated FE model of the human thorax named Hermaphrodite Universal Biomechanical YX model (HUBYX model). These previous validations included replications of standard experimental tests often used to validate models in the context of automotive industry, experimental ballistic tests in high speed dynamic impact and also numerical replication of blast loading test ensuring its biofidelity. In order to extend the use of this model in other frameworks, some real-world accidents were reconstructed, and consequences of these loadings on the FE model were explored. These various numerical replications of accident coming from different contexts raise the question about the ability of a FE model to correctly predict several kinds of trauma, from blast or ballistic impacts to falls, sports or automotive ones in a context of numerical injury mechanisms and tolerance limits investigations.

Fall from a car driving at high speed: A case report

In cases of falls, the key issue for forensic scientists is to determine the manner of death. They must distinguish between accidental falls, suicidal falls, falls including blows and falls caused by a blow. Several strategies have been proposed in the literature to help explain injury patterns. Here, we report an original case of a man who died after jumping from a car moving at high speed. A mathematical and modeling approach was developed to reconstruct the trajectory of the body in order to understand the injury pattern and apparent discrepancy between the high speed of the car from which the victim jumped and the topography of the bone fractures, which were limited to the skull. To define the initial values of the model's parameters, a technical vehicle evaluation and several test jumps at low speed were carried out. We studied in greater detail the trajectory of three characteristic points corresponding to the dummy's center of gravity, head and right foot. Calculations were made with and without the air friction effect to show its influence. Finally, we were successful in modeling the initial trajectory of the body and the variation of its head energy over time, which were consistent with the injuries observed.

A fatal fall associated with undiagnosed parenchymatous neurosyphilis

A fall from a great height is often associated with altered mental status. Aside from the usual contributing factors, for example, alcohol consumption or mental illness, natural disease leading to a fatal fall is seldom identified by autopsy. The case described in this report is that of a 57-year-old man who had been clinically diagnosed with presenile Alzheimer disease and fell head first into a river from the bridge. These events were captured by a surveillance camera on the bridge; an acquaintance reported that he had previous suicidal ideation. At autopsy, the cervical spinal cord was determined to have been severely injured, and the sixth cervical vertebra was observed to have been fractured. Histological examination showed chronic meningoencephalitis including neuronal loss, perivascular cuffing, and the proliferation of microglia and astrocytes in the cerebral cortex. Serologic evaluation consisting of the nontreponemal antigen test (rapid plasma reagin [RPR]) and treponemal antibody test (Treponema pallidum latex agglutination) was positive in both cases (RPR: 18.2 RPR units, T. pallidum latex agglutination: 7718 U/mL). These findings suggested that the patient had been affected by a syphilis infection and that his suicidal behavior was associated with parenchymatous neurosyphilis.

Fall from a balcony--accidental or homicidal? Reconstruction by numerical simulation

In the case presented, conflicting witness accounts and the subject's injuries were highly suspicious of an assault that might have caused the balcony fall. For the reconstruction, a simulation software, originally designed for motor vehicle accident reconstruction, was used. Three scenarios were simulated using the PC-Crash multibody pedestrian model: (S1) Subject was pushed against and fell over balcony rail, (S2) subject fell off from a seated position, (S3) subject fell off from a prone position on the rail. (S1) could be ruled out due to inconsistent results in terms of landing area and minimum velocity. Realistic results were obtained for (S3) with a fall off from a prone position on the rail. After a few months, the comatose subject awoke and gave an account of what had happened being consistent with the simulation results. This case demonstrates the feasibility of multibody simulations also in cases of nontraffic incidents.

Histological diagnosis of myocardial sarcoidosis in a fatal fall from a height

The major issues of medico-legal relevance in fatal falls from a height are the manner of death and the reconstruction of the event. We present a peculiar case of a fatal fall from a height of about 9 m, involving a 27-year-old woman. At the death scene investigation, no suicide notes, housebreaking marks, or signs of fight were found, thus weakening both the suicide and homicide hypotheses. Combining circumstantial, autopsy and toxicology data, the kinematic analysis of the jump/fall, and the histological evidence of a myocardial sarcoidosis involving the left ventricle, we hypothesized that the young woman might have accidentally fallen from the window because of a sudden loss of consciousness related to cardiac disease undiagnosed during life. We believe that our brief report is a good example of the powerful additional information that histological investigations can offer for reconstructing the dynamics of the event in falls from a height and other traumatic fatalities.

Determining falling patterns by estimation of horizontal distance and height

Whether by accident or foul play virtually thousands of fall-related fatalities occur each year. While a number of past studies addressed the relationship between falls, injury, and death, only a small fraction sought to establish an objective index geared specifically towards determining the cause of a particular fall. The primary objective in the present study was to determine the range of attainable horizontal distances in various forms of active and passive falling patterns. The secondary objective involved the capturing of physical motions at the point of impact via 3D motion analyses in order to identify the defining physical characteristics of a particular form of fall. The introduction of live test subjects to these series of experiments added the advent of fear and other psychological factors to the study which are crucial in simulating real-life cases. To corroborate this point, five subjects (three male and two female) expressed their wishes to withdraw from the study, attributing their decision to feeling an inherent danger and fear of the physical aspects of the present study. The ten subjects were made to fall from a height of 3.65 m under 13 conditions of various natures. Footage of the subjects falling was captured on two high-speed video cameras which markedly improved the calculation of 3D coordinates along the subjects' flight path. After extensive calculations, we were successful in determining the maximum attainable horizontal distances in passive falling patterns. Additionally, we found that force applied to the abdominal area results in shorter horizontal distances in comparison to falls where force is directly applied to the posterior side of the body.