Experimental investigation on mean crushing stress characterization of carbon–epoxy plies under compressive crushing mode

A challenge in numerical simulation of crashworthiness study is to be able to predict the crush damage modes, their evolution during crushing and the energy absorption in any composite structure from elementary material characterisation data. Therefore, it is important to know the behavior of one ply subjected to crushing load, and especially to determine the mean crushing stress that could be used for simulation. For that purpose, quasi-static crushing tests are performed for different configurations of two CFRP materials, UD and fabrics to determine the mean crushing stress of plies alone and inside a laminate. This study shows there is a linear relationship between crushing load and the contact surface of the plies being crushed on a metallic base which enables actually to define a mean crushing stress for a ply. The method to calculate this value is presented in this paper, based on image analysis of specific crushing tests. Experimental results show that for the UD material, the mean crushing stresses in 0° and 90° plies are very close. The value for a balanced fabric is also similar, approximately 270 MPa

Initiation and propagation mechanisms of progressive crushing in carbon-epoxy laminated plates

This article presents original experiments that enhance the understanding of the mechanisms that drive the progressive crushing of fiber-reinforced laminated composite materials and their energy absorption capability. An innovative experimental fixture has been created in order to obtain detailed monitoring of quasi-static and dynamic crushing of laminated plates. The fixture enables the development of a regular crushing front through the whole width of the plate, without parasite rupture modes, and the real-time observation of this front with a high speed camera. Results of experimental works on fabric and unidirectional Carbon-Epoxy laminated composite plates are exposed. The obtained crushing modes are analysed, their stability and energy-absorbing capability are discussed

Calculating the state parameter in crushable sands

The state parameter (y) measures the distance from the current state to the critical state line (CSL) in the compression plane. The existence of a correlation between both the peak angle of shearing resistance (�# ) and peak dilatancy and y is central to many constitutive models used to predict granular soil behaviour. These correlations do not explicitly consider particle crushing. Crushing induced evolution of the particle size distribution influences the CSL position and recent research supports used of a critical state plane (CSP) to account for changes in grading. This contribution evaluates the whether the CSP can be used to calculate y and thus enable prediction of the peak angle of �# and peak dilatancy where crushing takes place. The data considered were generated from a validated DEM model of Fontainebleau sand that considers particle crushing. It is shown that where y is calculated by considering the CSL of the original uncrushed material there can be in a significant error in predicting the material response. Where the CSP is used there is a significant improvement in our ability to predict behaviour whether the CSP is accurately determined using a large number of tests or approximated using crushing yield envelopes. It is shown that the state parameter calculated using the previously available definition can give a false sense of security when assessing liquefaction potential of potentially crushable soils. The contribution also highlights the stress-path dependency of the relationship between �# $ and y whichever approach is used to determine

Treewidth, crushing, and hyperbolic volume

We prove that there exists a universal constant $c$ such that any closed hyperbolic 3-manifold admits a triangulation of treewidth at most $c$ times its volume. The converse is not true: we show there exists a sequence of hyperbolic 3-manifolds of bounded treewidth but volume approaching infinity. Along the way, we prove that crushing a normal surface in a triangulation does not increase the carving-width, and hence crushing any number of normal surfaces in a triangulation affects treewidth by at most a constant multiple.Comment: 20 pages, 12 figures. V2: Section 4 has been rewritten, as the former argument (in V1) used a construction that relied on a wrong theorem. Section 5.1 has also been adjusted to the new construction. Various other arguments have been clarifie

Impacts of China's Food Consumption on U.S. Soybean Exports

A model examines how the international and China’s market prices impact China’s soybean imports from the U.S. and South America. Based on soybean crushing ratios and a market clearing presumption, an equation of China’s soybean oil import prices is designed to achieve the goal.China's Soybean Imports, U.S. Soybean Exports, South American Soybean Exports, Price Elasticities, Soybean Crushing Ratios, Marke Clear, GMM, Agribusiness, International Relations/Trade, Q17,

Politics are Crushing the Standards

The recent news that Oklahoma Gov. Mary Fallin signed a bill to, in the parlance of the times, repeal and replace the common-core standards in her state was surprising, to say the least, notwithstanding a legal challenge to the repeal filed in the Oklahoma Supreme Court by parents, teachers, and state board of education members on June 25. Before Gov. Fallin was against the standards, she supported them. [excerpt

PERANCANGAN MESIN PENGEPRES SAMPAH ORGANIK KAPASITAS 250 KG / JAM

Rubbish is one of the most important problems nowadays. This problem related to the huge number of rubbish. Many ways have been conducted to solve this problem. One way\ud of processing rubbish is by machine. Producing machine for rubbish commonly is crushing machine or pressing machine. The purpose of this thesis is to design pressing machine for\ud organic rubbish by capacity 250 kg/hours. This design is based on the integrated concept of cutting system from pressing result. Crushing system is designed by using knives arrangement that is rotated in its axes. The\ud pressing process is designed by using shaft wheel mechanism and pressing plate that is equipped by spring. While, cutting system by using 2 blades is positioned rotating in axes end. The design is initiated by calculation of machine capacity and is continued by calculation of driving force of electrical motor. Then, there is needed calculation of design machines components needed; they are knives, axes, pulley and belt, cone gearwheel, axis, shaft and crank mechanism. Besides, there is also needed supporting system planning contains knives seizer, crushing cylinder wall, frame and machine cover and pelat mechanism and spring.\ud The result of design is machine that consists of 3 systems; they are crushing system, pressing system and cutting system. This machine needs driving force of electric motor by 2,5 HP (1,84 kW). Crushing system by using 7 movements of cutting knife in the axis by speed of rotation 300 rpm. Pressing system is using mechanism of shaft wheel boost pressing piston. Shaft movement has speed rotation of 60 rpm, it means there is 60 times rotation in a minute. Cutting system by using 2 blades is moved by axis in 30 rpm. By this speed, then in every minute there is 60 times of cutting process to compensate pressing movement

Crushing Modes of Aluminium Tubes under Axial Compression

A numerical study of the crushing of circular aluminium tubes with and without aluminium foam fillers has been carried out to investigate their buckling behaviours under axial compression. A crushing mode classification chart has been established for empty tubes. The influence of boundary conditions on crushing mode has also been investigated. The effect of foam filler on the crushing mode of tubes filled with foam was then examined. The predicted results would assist the design of crashworthy tube components with the preferred crushing mode with the maximum energy absorption