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Properties and applications of engineering materials
Published in Alan Darbyshire, Charles Gibson, Mechanical Engineering, 2023
Alan Darbyshire, Charles Gibson
Toughness is the ability of a material to withstand impact and shock loading. The standard tests for toughness are the Izod impact test and the Charpy test. Both use the same testing machine in which a notched specimen is subjected to a sudden blow from a swinging pendulum (Figure 5.26).
Mechanical Properties of Metals and Alloys
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
Toughness is a measure of the energy required to fracture a given material. Fracture can be brittle or ductile. Brittle fracture occurs with little or no plastic deformation, while ductile fracture involves plastic deformation with cracks propagating in a stable manner to failure. Figure 4.17a shows the schematic stress-strain curves for brittle and ductile materials. Note the contrast between no plastic deformation for the brittle material and extensive plastic deformation for the ductile material. Toughness is the area under the stress-strain curve. Although we usually associate brittle materials as less tough than ductile materials as illustrated in Figure 4.17a, such association is not always true. For example, some bulk metallic glass alloys are brittle but tough; many polymers are ductile but not tough. Figure 4.17b and c compares the morphology of fracture surfaces from brittle and ductile materials: faceted appearance of the former and fine dimpled appearance of the latter are typical of these materials, respectively.
Fundamentals of Linear Elastic Fracture Mechanics
Published in Cameron Coates, Valmiki Sooklal, Modern Applied Fracture Mechanics, 2022
Cameron Coates, Valmiki Sooklal
An increase in temperature within a material implies that the kinetic energy of the atoms increases, that is the amplitude and velocity of the atomic vibrations will increase. Therefore dislocations, the mechanism responsible for plastic deformation, will occur more frequently and move at a faster rate. The material therefore tends to have increased ductility. Generally, as temperature increases, the fracture toughness of a material will increase.
Cotton fibre elongation: a review
Published in The Journal of The Textile Institute, 2022
C. D. Delhom, J. D. Wanjura, E. F. Hequet
Measuring the tensile properties of a cotton sample is performed by clamping a single fibre or bundle of fibres between two clamps or jaws. One jaw is fixed in place, while the other jaw is movable and used to apply a load along the main axis of the material until the material fractures (Figure 1). The force applied to the material is monitored, as is the elongation. The elongation of the material is the percent increase in the gauge length during the test. The gauge length is the initial distance between the two clamps. A tensile test will produce breaking strength and elongation results, and the relationship of the two properties can be illustrated by the resultant tenacity-elongation curve (Figure 2). The cotton industry has primarily focused on cotton strength, which is only one component of the tensile properties of cotton, likely due to the ease of an accurate measurement of strength. Cotton fibre elongation makes up the other component to properly characterize the tensile properties of a material. The area under the strength-elongation curve represents the energy required to break the sample. Toughness is the ability of a material to absorb energy and experience plastic deformation before rupture. When taken together, the breaking strength and elongation allow the material’s toughness to be characterized. However, fibre elongation is not part of the official classification of cotton, even if H.V.I. can report breaking elongation values (Taylor, 1986).
Influence of incinerated biomedical waste ash and waste glass powder on the mechanical and flexural properties of reinforced geopolymer concrete
Published in Australian Journal of Structural Engineering, 2022
Suresh Kumar A, Muthukannan M, Arun Kumar K, Chithambar Ganesh A, Kanniga Devi R
Toughness is a characterising property of a substance based on how much energy it can withstand during plastic deformation. Materials of poor toughness appear to show abrupt fragile degradation. Consequently, a persistent and apparent inability to preserve the system’s safety usually results in a more prolonged outage (considered essential for protected structural members). The quantity of energy needed to break the beam initially and then deflect the beam afterwards in order to the desired deflection is found by means of standardisation in ASTM C1018-1997 (also in a 4-point configuration). Table 7 summarises the toughness indices for the different beam samples. The maximum allowable strains can be described as the flexural toughness indices (i.e., I5, I10, I20, and I30), and the ratio of the energy absorbed to the energy needed to achieve the additional deflection times the number of consecutive deflections that they produce is calculated.
Performance analysis of heat treated AISI 1020 steel samples on the basis of various destructive mechanical testing and microstructural behaviour
Published in Australian Journal of Mechanical Engineering, 2022
Saurabh Dewangan, Neha Mainwal, Manwi Khandelwal, Prateek Sunil Jadhav
Charpy impact test was performed to measure the toughness of each sample. For this, an impact testing machine made by SunLabTek Equipments Pvt. Ltd., India was used. The model name of this machine is SUN-30 (ASTM) Charpy Test. It has maximum capacity and minimum scale graduation as 300 and 2 J, respectively. Toughness is defined as energy absorbed by the material up to fracturing. Hence, toughness imparts area under the stress–strain curve. In general, toughness depends on ductility of material means highly ductile material shows high toughness value. It is usually measured in Joule. In this experiment, a freely falling hammer hitting technique was used to measure the toughness. As the samples were already prepared according to ASTM standard prior to heat treatment, cleaning of the samples was only remaining work for impact testing. Initially, to check any error of the machine, the hammer was freely fall without putting any sample. An error of 5 J was recorded in the impact machine which was considered for finding the exact value of toughness. The impact test results and their analysis are shown in Figure 8.