The Specific Energy Modal Components of the Impact Dynamic Loads in a Solid

Carbon fibre composite tubes have high strength to weight ratios and outstanding performance under axial crushing. In this paper, square CFRP tubes and aluminium sheet-wrapped CFRP tubes were impacted by a drop mass to investigate the effect of loading velocity on the energy absorption of CFRP/aluminium tubes. A comparison of the quasi-static and dynamic crushing behaviours of tubes was made in terms of deformation mode, peak crushing force, mean crushing force, energy absorption and specific energy absorption. The influence of the number of aluminium layers that wrapped square CFRP tubes on the crushing performance of tubes under axial impact was also examined. Experimental results manifested similar deformation modes of tubes in both quasi-static and dynamic tests. The dynamic peak crushing force was higher than the quasi-static counterpart, while mean crushing force, energy absorption and specific energy absorption were lower in dynamic tests than those in quasi-static tests. The mean crushing force and energy absorption decreased with the crushing velocity and increased with the number of aluminium layers. The impact stroke (when the force starts to drop) decreased with the number of aluminium layers.

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Experimental Examination of the Impact of Tool Radius on Specific Energy in Microcutting of Granite

Journal of Engineering Materials and Technology ◽

10.1115/1.4036585 ◽

2017 ◽

Vol 139 (4) ◽

Cited By ~ 1

Author(s):

Miloš Pjević ◽

Ljubodrag Tanović ◽

Goran Mladenović ◽

Biljana Marković

Keyword(s):

Cutting Force ◽

Penetration Depth ◽

Specific Energy ◽

Brittle Materials ◽

Experimental Examination ◽

Workpiece Surface ◽

Different Shapes ◽

Tip Radius ◽

The Impact ◽

Force Intensity

The paper presents experimental results of microcutting brittle materials (granite). The analysis was conceived on the observed interaction between the workpiece and two tools of different shapes. Experiment was based on scratching the workpiece surface with diamond tools. Applied tools had tip radius R0.2 and R0.15 mm. The experiment determined the changes in the value of perpendicular and tangential components of the cutting force based on the geometric properties of tools, as well as the changes of the specific energy of microcutting granite (Jošanica and Bukovik types). The experiment has shown that reduction of tool radius causes reduction of the cutting force intensity and specific cutting energy. Because of its physical/mechanical properties, more energy is required for micromachining granite “Jošanica” than “Bukovik.” Based on the topography of the surface, the value of critical tool penetration depth was established, after which the brittle fracture is no longer present. For granite “Jošanica” values of critical penetration depth are 6 and 5 μm when micromachining with tools R0.2 and R0.15 mm, while for Bukovik those values are 6.5 and 5.5 μm. The paper should form the basis for understanding the phenomena which occur during microcutting brittle materials.

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The Specific Characteristics of Shock and Blast Impacts on Construction Sites

Occupational Safety in Industry ◽

10.24000/0409-2961-2021-9-81-88 ◽

2021 ◽

pp. 81-88

Author(s):

A.A. Komarov ◽

Keyword(s):

Dynamic Load ◽

Static Load ◽

Dynamic Loads ◽

Potential Hazard ◽

Construction Sites ◽

Static Loads ◽

Equivalent Static Loads ◽

Plane Crash ◽

Nuclear Plants ◽

The Impact

The practices of hazardous and unique facilities’ construction imply that specific attention is paid to the issues of safety. Threats associated with crash impacts caused by moving cars or planes are considered. To ensure safety of these construction sites it is required to know the potential dynamic loads and their destructive capacity. This article considers the methodology of reducing dynamic loads associated with impacts caused by moving collapsing solids and blast loads to equivalent static loads. It is demonstrated that practically used methods of reduction of dynamic loads to static loads are based in schematization only of the positive phase of a dynamic load in a triangle forms are not always correct and true. The historical roots of this approach which is not correct nowadays are shown; such approach considered a detonation explosion as a source of dynamic load, including TNT and even a nuclear weapon. Application of the existing practices of reduction of dynamic load to static load for accidental explosions in the atmosphere that occur in deflagration mode with a significant vacuumization phase may cause crucial distortion of predicted loads for the construction sites. This circumstance may become a matter of specific importance at calculations of potential hazard of impacts and explosions in unique units — for instance, in the nuclear plants. The article considers a situation with a plane crash, the building structure load parameters generated at the impact caused by a plane impact and the following deflagration explosion of fuel vapors are determined.

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Aeroelastic Tailoring of Helicopter Blades

Volume 7A: 9th International Conference on Multibody Systems, Nonlinear Dynamics, and Control ◽

10.1115/detc2013-12848 ◽

2013 ◽

Author(s):

Donatien Cornette ◽

Benjamin Kerdreux ◽

Yves Gourinat ◽

Guilhem Michon

Keyword(s):

Dynamic Behaviour ◽

Vertical Shear ◽

Dynamic Loads ◽

Modal Approach ◽

Aeroelastic Tailoring ◽

Helicopter Blades ◽

Shear Modification ◽

Elastic Couplings ◽

The Impact ◽

Aerodynamic Lift

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization is done thanks to couplings between the flapwise-bending motion and the torsion motion. The impact of elastic couplings (composite anisotropy) on the blade dynamic behaviour and on dynamic loads are evaluated in this paper. Firstly, analytical results, based on a purely linear modal approach, are given to understand the influence of those couplings in terms of frequency placement, aerodynamic lift load and vertical shear modification. Then, those elastic couplings are introduced on a simplified but representative blade (homogeneous beam with constant chord) and results are presented.

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Impact Coefficient Analysis of Curved Box Girder Bridge Based on Vehicle-Bridge Coupling

Mathematical Problems in Engineering ◽

10.1155/2022/8628479 ◽

2022 ◽

Vol 2022 ◽

pp. 1-11

Author(s):

Fei Guo ◽

Heng Cai ◽

Huifang Li

Keyword(s):

Shear Force ◽

Primary Beam ◽

Dynamic Loads ◽

Box Girder ◽

Impact Coefficient ◽

Force Impact ◽

Girder Bridge ◽

The Moment ◽

The Impact ◽

Load Weight

In the current vehicle-bridge dynamics research studies, displacement impact coefficients are often used to replace the moment and shear force impact coefficients, and the vehicle model is also simplified as a moving-load model without considering the contribution of vehicle stiffness and damping to the system in some concerned research studies, which cannot really reflect the mechanical behavior of the structures under vehicle dynamic loads. This paper presents a vehicle-bridge coupling model for the prediction of dynamic responses and impact coefficient of the long-span curved bending beam bridge. The element stiffness matrix and mass matrix of a curved box girder bridge with 9 freedom degrees are directly deduced based on the principle of virtual work and dynamic finite element theory. The vibration equations of vehicle-bridge coupling are established by introducing vehicle mode with 7 freedom degrees. The Newmark-β method is adopted to solve vibration response of the system under vehicle dynamic loads, and the influences of flatness of bridge surface, vehicle speed, load weight, and primary beam stiffness on the impact coefficient are comprehensively discussed. The results indicate that the impact coefficient presents a nonlinear increment as the flatness of bridge surface changes from good to terrible. The vehicle-bridge coupling system resonates when the vehicle speeds reach 60 km/h and 100 km/h. The moment design value will maximally increase by 2.89%, and the shear force design value will maximally decrease by 34.9% when replacing moment and shear force impact coefficients with the displacement impact coefficient for the section internal force design. The load weight has a little influence on the impact coefficient; the displacement and moment impact coefficients are decreased with an increase in primary beam stiffness, while the shear force impact coefficient is increased with an increase in primary beam stiffness. The theoretical results presented in this paper agree well with the ANSYS results.

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Empirical Analysis of the Impact Strength of Textile Knitted Barrier Meshes

Autex Research Journal ◽

10.2478/aut-2020-0030 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Zbigniew Mikołajczyk ◽

Beata Szałek ◽

Katarzyna Pieklak

Keyword(s):

Measurement Data ◽

Test Stand ◽

Dynamic Loads ◽

Measuring System ◽

Electronic Measuring ◽

Computer Data ◽

Analysis System ◽

Data Analysis System ◽

Dynamic Stress Distribution ◽

The Impact

AbstractThe assumptions of instrumental methodology for measuring dynamic loads of knitted barrier meshes were defined. A test stand was built, original in terms of both mechanical construction and electronic measuring system, connected to a computer data analysis system. Maximum values of dynamic forces in the mesh fastening strings were determined. The correctness of the strain gauges construction and measurement data transmission systems was confirmed. Tests of multidirectional resistance to dynamic loads in the mesh fastening strings were carried out. The experiment involved dropping a ball with a mass of 5 kg and a diameter of 10 cm, from a height of 1 m and 2 m onto the mesh surface. The potential impact energy equaled Ep1 = 49.05 J and Ep2 = 98.1 J. The tests showed that the highest force values were observed for meshes with square-shaped a-jour structure, and for mesh with diamond-shaped a-jour geometry the force values were lower. A symmetrical forces distribution was observed in all the strings. The highest forces were recorded in the middle strings and the lowest in the outer ones. The conducted tests confirmed the correctness of the adopted constructional solutions of test stand for identification of dynamic stress distribution in mesh fastening strings. The developed method is a useful verification tool for numerical analysis of mechanical properties of barrier meshes.

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Numerical Analysis on the Response of Deck Plates Laterally Impacted by a Rectangular Indenter

Volume 11A: Honoring Symposium for Professor Carlos Guedes Soares on Marine Technology and Ocean Engineering ◽

10.1115/omae2018-78023 ◽

2018 ◽

Author(s):

Ling Zhu ◽

Junying Gao ◽

Yinggang Li

Keyword(s):

Permanent Deformation ◽

Dynamic Loads ◽

Parametric Studies ◽

Ice Floes ◽

Maximum Impact Force ◽

Impact Energies ◽

The Impact ◽

Deformation Modes ◽

Theoretical Procedure ◽

Good Agreement

Ship deck plates are often subjected to localized dynamic loads, such as the loads of landing helicopter or impacts of ice floes. In order to investigate the dynamic response of ship plates subjected to such dynamic loads, a series of numerical simulations are performed on ship plates with different thicknesses. Parametric studies are performed on the impact response of plates, including the thickness of the plates, mass and impact velocity of the rectangular indenter. The maximum permanent deflections of the plates are obtained during the simulation. The relation between maximum force and permanent deflection is obtained and the deformation modes are analyzed. A theoretical procedure is developed to predict the deformation of plates with different initial impact energies, and a good agreement between the theoretical and numerical results is obtained. It has also been observed that the thickness of plates has little effect on the dimensionless maximum permanent deformation and dimensionless maximum impact force.

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Research of Properties of Austenitic Steels

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.887.242 ◽

2021 ◽

Vol 887 ◽

pp. 242-246

Author(s):

A.A. Peregudov ◽

S.A. Vologzhanina ◽

A.F. Igolkin

Keyword(s):

Low Temperatures ◽

Far East ◽

Austenitic Steels ◽

Dynamic Loads ◽

Complex State ◽

Corrosion Resistant ◽

The Far East ◽

Static And Dynamic Loads ◽

The Impact ◽

Strength And Ductility

Active development of the territories of Siberia and the Far East requires the use of materials that are able to work under the combined influence of low temperatures and a complex state. When operating equipment parts at low temperatures, it is necessary to take into account the impact of static and dynamic loads, as well as the influence of an external aggressive environment. The paper studies corrosion-resistant cold-resistant metastable austenitic steels, which are widely used for manufacturing parts of low-temperature equipment. Tests were performed to assess the strength and ductility characteristics of smooth samples and samples with annular notches for static stretching in the temperature range from 293 to 77 K.

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Mathematical Modeling of Impact of Possible Shock Dynamic Loads on the Modern Composite Materials

EPJ Web of Conferences ◽

10.1051/epjconf/201922402012 ◽

2019 ◽

Vol 224 ◽

pp. 02012

Author(s):

Eugenе Sosenushkin ◽

Oksana Ivanova ◽

Elena Yanovskaya ◽

Yuliya Vinogradova

Keyword(s):

Composite Materials ◽

Friction Force ◽

Equations Of Motion ◽

Elastic Fiber ◽

Dynamic Loads ◽

Friction Forces ◽

Absolute Value ◽

A Value ◽

The Absolute ◽

The Impact

In this paper, we study the dynamic processes in materials reinforced with fibers, that can be represented as composite rods. There has been developed a mathematical model of wave propagation under the impact of a shock pulse in semi-infinite composite rods. It is believed that the considered composite rod consists of two layers formed by simpler rods of different isotropic materials with different mechanical properties. The cross sections of such rods are considered to be constant and identical. When such composite materials are impacted by dynamic loads, a significant part of the energy is dissipated due to the presence of friction forces between the contact surfaces of the rods. In this regard, we study the propagation of waves in an elastic fiber-rod, the layers of which interact according to Coulomb law of dry friction. The case of instantaneous excitation of rods by step pulses is investigated. The blow is applied to a rod made of a harder material. In the absence of slippage, the friction force gets a value not exceeding the absolute value of the limit. In the absence of slippage, the friction force takes a value not exceeding the absolute value of the limit. Let us consider the value of the friction force constant. Normal stresses and velocities satisfy the equations of motion and Hooke’s law. The problem statement results in the solution of inhomogeneous wave equations by the method of characteristics in different domains, which are the lines of discontinuities of the solution. Solutions are found in all constructed domains. On the basis of the analysis of the obtained solution, qualitative conclusions are made and curves are constructed according to the obtained ratios. From the found analytical solution of the problem it is possible to obtain ratios for stresses and strain rates in composite rods and composite materials.

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Physico-Mechanical Properties of the Poly(oxymethylene) Composites Reinforced with Glass Fibers under Dynamical Loading

Polymers ◽

10.3390/polym11122064 ◽

2019 ◽

Vol 11 (12) ◽

pp. 2064 ◽

Cited By ~ 1

Author(s):

Stanisław Kuciel ◽

Patrycja Bazan ◽

Aneta Liber-Kneć ◽

Aneta Gądek-Moszczak

Keyword(s):

Mechanical Properties ◽

Glass Fiber ◽

Fiber Diameter ◽

Glass Fibers ◽

Fiber Reinforced Composites ◽

Dynamic Loads ◽

Fatigue Properties ◽

Reinforced Composites ◽

The Impact ◽

Microscopy Images

The paper evaluated the possibility of potential reinforcing of poly(oxymethylene) (POM) by glass fiber and the influence of fiberglass addition on mechanical properties under dynamic load. Four types of composites with glass fiber and another four with carbon fiber were produced. The fiber content ranged from 5% to 40% by weight. In the experimental part, the basic mechanical and fatigue properties of POM-based composites were determined. The impact of water absorption was also investigated. The influence of fiber geometry on the mechanical behavior of fiber-reinforced composites of various diameters was determined. To refer to the effects of reinforcement and determine the features of the structure scanning electron microscopy images were taken. The results showed that the addition of up to 10 wt %. fiberglass increases the tensile properties and impact strength more than twice, the ability to absorb energy also increases in relation to neat poly(oxymethylene). Fiber geometry also has a significant impact on the mechanical properties. The study of the mechanical properties at dynamic loads over time suggests that composites filled with a smaller fiber diameter have better fatigue properties.

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