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Precast segmental bridge construction in seismic zones
Published in Fabio Biondini, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Resilience and Sustainability, 2012
Fabio Biondini, Dan M. Frangopol
The bridge girder cross-bridge caused by ship- collision is a typical shock to decay, which is characterized by is horizontal angle value after ship- collision appearing a sudden increase and then gradually decaying in the reciprocation vibration (of course, there may be more collision, so it may also appear that the first pair of peak value is not the maximum or minimum point of the amplitude in the whole period of the impact event, and what may exist is that the peak value in the first few cycles of vibration remains unchanged or even increased slightly, then gradually decays); while, vehicles- induced vibration and wind-induced vibration are generally excited densely in a certain period of time, so it is often showing that the angle peak value is gradually increased after the alarming and then gradually reduced, in which the launch of the first peak is relatively low (Liu et al. 1998). Therefore, the first angle peak value of the first vibration cycle after activating the alarming can be selected as ship- collision characteristic indicator B of bridge girder.
Scientific Rationale for Planetary Drilling
Published in Yoseph Bar-Cohen, Kris Zacny, Advances in Extraterrestrial Drilling, 2020
H. M. Sapers, L. W. Beegle, C. M. Caudill, E. Cloutis, J. Dickson, P. Hill
The scale of geologic context can change as a function of the specific question being investigated. For an outcrop geologist studying precipitation of minerals and the shape of vugs where concretions used to be, the outcrop itself is the context. For an orbital spectroscope, that same outcrop viewed in a hyper-spectral image is at the limit of that sensor’s resolution, such that it is the primary target and the context is the crater wall within which the outcrop is found. Understanding the scale of context being investigated is essential for proper framing of what question is being addressed, and geologic context provides the scale at which proper geologic questions are asked. Drilling is expensive and labor-intensive, such that scattershot sampling without planning with the hope of sampling something of interest is inefficient and likely to fail; this is why the first vertical cores extracted from Mars or any other planet will require extensive geological reconnaissance before execution. While a planetary enthusiast would say that any core extracted from any site on any planetary body will provide valuable information, and they would be right, the context of that core promotes the data returned from the realm of trivia to geologic information pertaining to the origin and evolution of the unit under investigation. Was the core extracted from the central peak of an impact crater, representing uplifted material that existed before the impact event, or from a resurfaced crater floor, such that accessed material are units formed after the impact event? Geologic context is what gives the data extracted from the core meaning.
Flexible Protective Armor: Modern Designs
Published in Magdi El Messiry, Protective Armor Engineering Design, 2019
The total kinetic energy of the bullet lost during the ballistic impact event is equal to the total energy absorbed by the fiber reinforced polymer composite target until the time interval to pass through it. During the penetration of the bullet in the hard plate, it should have kinetic energy sufficient to overcome following resistance energies: Energy of compressive stress due to the compactness of the plate at the area of contact with the bullet tip.Frictional energy absorbed during interaction of the penetrator and laminate.Energy of delamination.Energy of matrix cracking.Energy of elastic deformation of the secondary yarns.Energy of tensile fiber failure of the primary yarns.Energy absorption because of shear plugging.Energy absorbed due to fiber-matrix debonding and pull-out.Energy absorption based on laminate parameters andEnergy absorption due to cone formation.
Compression after impact of CFRE composites immersed in distilled water
Published in International Journal of Crashworthiness, 2021
Ramzi Othman, U.A. Khashaba, Khalid H. Almitani
Fiber reinforced polymer (FRP) composite laminates are increasingly used in aerospace and aeronautical engineering because they offer high specific mechanical properties [1,2]. They are mainly used in purpose of light-weighting. In airplanes, polymer composites can be used either in fuselages, empennages, wing boxes or engines, helicopter rotor blades, etc. During service life, the composite structures are usually exhibited to low-velocity impacts, such as hammer, service collisions, bird strike, tools drop during maintenance operations or tire debris impact [3–5]. If the impact energy is higher than a critical value, the low-velocity impacts damage the composite material. At high-velocity impact the induced damage is mostly characterised in visible holes due to the penetration of projectiles [6]. On the opposite of high velocity impacts [6–8], the induced damage is barely visible and hard to detect by simple external inspection [9,10]. The intensity and type of the impact damage is extremely influenced by the environmental conditions associated with the impact event. The strength of the impact-damaged composite structures can be 50–75% less than the strength of the undamaged structures [5]. This barely visible damage is critical to aerospace composite structures [10]. It is a real menace as it can accelerate failure due to fatigue, for example [11].