Shock and friction as explanations for disaster at the Battle of Amiens, 8 August 1918

The assault at Amiens was ‘the black day of the German Army’. British accounts treat the Germans as passive, of no more importance than the terrain, and victory as inevitable. Using German sources, and drawing on statistical ‘historical analysis’ of behaviour in battle, the article argues the frontline defenders panicked when thick fog left them defenceless against the British tanks. By contrast, when the fog lifted, the defence recovered. Although senior German commanders on the spot reacted well, Ludendorff fell into a state of shock, such that he convinced the Kaiser the war must be ended.     

Shock Response from Pseudodynamic Test Using Momentum Equations of Motion

The feasibility of using pseudodynamic techniques to yield shock responses from impulses is studied herein. A direct integration method is often used to solve the force equation of motion in performing a conventional pseudodynamic test. However, this technique might not be applicable to obtain an accurate shock response from an impulse as a load discontinuity occurs at the end of the impulse. This is because this discontinuity will lead to an extra amplitude distortion and the amount of this amplitude distortion is increased with the increase of time step. Hence, a small time step is needed to reduce the extra amplitude distortion and thus the displacement increment for each time step might be smaller than or as small as the resolution of the displacement transducer. As a result, the displacement increment cannot be accurately imposed upon the specimen and the responses will be contaminated by the noise. In addition, the test duration is drastically increased. Alternatively, this difficulty might be overcome if the momentum equation of motion instead of the force equation of motion is solved pseudodynamically. Hence, an external momentum is used in the solution of the momentum equation of motion. Since the external momentum is a resultant of the time integration of the external force the discontinuity problem will automatically disappear. Consequently, reliable shock responses can be obtained from pseudodynamic tests.     

Radiologic proof for the Iceman's cause of death (ca. 5’300 BP)

A possible cause of death of the Iceman – a ca. 5’300 BP natural human glacier mummy from the Tyrolean Alps – is an intrathoracic stone arrowhead. The aim of this study was to prove radiologically his enigmatic cause of death. In August 2005, the Iceman underwent his first multislice computed tomography examination. As the main pathologic finding, the left dorsal subclavian artery contures shows a 13 mm-long part where the vessel wall is damaged and a 3 mm-long irregular pseudo-aneurysm – a typical complication of a laceration of the subclavian artery. In the surrounding soft tissue a large haematoma is visible. Historic records highlight the fatal destiny of subclavian artery injuries e.g. due to massive active bleeding and shock-related cardiac arrest. Therefore, the Iceman's cause of death by an arrowhead lacerating among others the left subclavian artery and leading to a deadly hemorrhagic shock can be now postulated with almost complete certainty, especially when taking the environmental (3’210 meters above sea level) and historic (5’300 BP) settings into account.     

Strength,Toughness and Thermal Shock Resistance of Ancient Ceramics,and Their Influence On Technological Choice

The basic underlying theory for the strength, toughness and thermal shock resistance of brittle multiphase clay ceramics, together with the measurement procedures to determine these parameters, are first outlined. Published experimental data obtained for test bars containing different types of temper and fired to a range of temperatures are then compared both with theoretical predictions and between themselves. The results confirm that to produce pottery with high strength requires high firing temperatures and low temper concentrations. Conversely, to produce pottery with high toughness and thermal shock resistance requires low firing temperatures and high temper concentrations, with platy or fibrous temper being most effective. There is no convincing published evidence that strength and toughness requirements were a significant factor in determining the technological choices (clay type, temper type and concentration, and firing temperature) in the production of pottery used as containers for transport and storage. In contrast, the routine use of high temper concentrations and low firing temperatures in the production of cooking pots suggests that the requirement for high thermal shock resistance was a factor that at least influenced technological choice in this case. In addition, there is some evidence that limestone and shell were, on occasions, deliberately chosen as temper in cooking pots. The need to take into account the crucial role that the full range of environmental, technological, economic, social, political and ideological factors have in influencing technological choice is also emphasized. This review highlights the fact that our current understanding of the factors determining strength, toughness and thermal shock resistance of clay ceramics is still far from complete. Further systematic measurements of these parameters, together with the establishment of a systematic database of the range of technological choices associated with the production of cooking pots, are therefore to be encouraged.     

A Simple Model for Estimating Shocks in Unrestrained Building Contents in an Earthquake

Building contents that include cabinets housing electronic equipment are typically not rigidly secured to the floor, nor to the adjacent wall except in regions of high seismic activities. The behavior of unrestrained building contents in an earthquake is a cause of concern because of the consequence of damage to certain equipment or other forms of fragile items. Much of the research reported in the literature has been devoted to studying the rocking and sliding motion behavior of base-excited rigid objects and their risks of overturning. In contrast, this paper is concerned with estimating the impact acceleration that can be generated by the pounding of the rocking object onto the floor. Algebraic expressions for predicting the acceleration level, which can be translated into dynamic force values, are derived and illustrated by case studies. Importantly, the proposed expressions have been verified by comparisons with results from both simulated and physical experiments. In illustrating the use of the proposed analytical procedure, a parametric experimental study has been undertaken on a cushion material to study the sensitivity of its static and dynamic stiffness to changes in the boundary conditions of the cushion. The proposed calculation procedure, while simple to apply, can be used as a means of predicting shock and the dynamic forces that can be generated in an object in the course of the response to an earthquake.