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Materials in Additive Manufacturing
Published in G.K. Awari, C.S. Thorat, Vishwjeet Ambade, D.P. Kothari, Additive Manufacturing and 3D Printing Technology, 2021
G.K. Awari, C.S. Thorat, Vishwjeet Ambade, D.P. Kothari
Full-color sandstone provides photo-realistic full-color models and sculptures and is particularly suited to architectural models, life-like sculptures, gifts and memorabilia, and fine arts. Essentially, it is made of gypsum and has a colored texture on the surface. The brittleness of the material limits its use as functional parts or as intricately designed parts. This sandstone material is sometimes referred to as multicolor.
Engineering Mechanics and Mechanical Behavior of Materials
Published in Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu, Interdisciplinary Engineering Sciences, 2020
Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu
Let us understand in this section, the origin of brittleness in ceramic materials. As it was previously discussed in Figure 4.2, it is important to recognize that non-linear deformation in metallic materials is the resultant of the dislocation movement. Analogously, in case of ceramics, propagation of cracks determines the mechanical response, as opposed to dislocation motion in metals. Even though ceramics have outstanding combinations of hardness, elastic modulus, compressive strength, ceramics are in general known for their brittleness (e.g., hydroxyapatite, Al2O3, etc.).
Applications to Fracture Mechanics
Published in Abdel-Rahman Ragab, Salah Eldin Bayoumi, Engineering Solid Mechanics, 2018
Abdel-Rahman Ragab, Salah Eldin Bayoumi
The term brittle here means fracture with no permanent deformation and a consumption of little energy. This is opposed to ductile fracture, which occurs after attaining appreciable plastic deformation and dissipating a large amount of energy. To apply this classification to a given material, it is now well recognized that it depends markedly on service conditions. For instance, low temperatures, high strain rates (e.g., impact), and hostile environment, together with the tensile regime of stresses, all promote brittleness. A material rated as ductile under normal (room) conditions may turn out to behave as a brittle one under adverse conditions. Consequently, a structure fabricated from a material conventionally rated as ductile at room conditions (e.g., low-carbon steel) may fail in a brittle manner because of the presence of cracks. Based on this global understanding, the subject of “Fracture Mechanics” is concerned with the prediction of steady or cyclic loading conditions that will cause fracture in a structure with preexisting cracks.
Effect of cryogenic oils-on-water compared with cryogenic minimum quantity lubrication in finishing turning of 17-4PH stainless steel
Published in Machining Science and Technology, 2020
Zhiwei Lai, Chengyong Wang, Lijuan Zheng, Haisheng Lin, Yaohui Yuan, Jianzhang Yang, Weiqiang Xiong
In the case of Cryo-CA and Cryo-LN, the cryogenic gas ensured a low-temperature environment that augmented the heat transfer. Besides, the low-temperature environment caused changes in the material properties, resulting in increased brittleness, lowered ductility and decreased work hardening (Bae et al., 2016). In addition, the oil film can maintain its lubrication ability for a longer period to decrease friction, which further lowers the cutting temperature. As a result, longer tool life and better processing quality can be achieved. It is worth noting that the lowest flank wear at RT is still slightly higher than the highest at Cryo-CA and is analogous to Cryo-LN. The results suggested that ensuring a low-temperature environment is more beneficial for extending the tool life than reducing the heat generation.
Undrained monotonic shear behavior of marine soft clay after long-term cyclic loading
Published in Marine Georesources & Geotechnology, 2020
Lin Guo, Hongxu Jin, Jun Wang, Li Shi
To further investigate the brittleness of specimens after cyclic loading, Figure 11 is drawn. The εM qfand εPC qf represent the axial strain corresponding to the maximum shear strength in standard monotonic tests and postcyclic monotonic tests, respectively. It can be seen from the figure that the shear strength of all postcylic monotonic tests reaches its maximum shear strength earlier than that of the monotonic tests. The result reflects that the specimens show more brittleness after long-term cyclic loading compared to that of standard monotonic tests, and the degree of brittleness increases with the increase of CSR. It is well known that materials showing brittleness under external forces will suddenly destroy without obvious deformation, and brittle materials have poor ability to resist impact load or vibration. That is to say, although the strength of clay specimens has not changed much after long-term cyclic loading, the brittleness of materials is unfavorable in engineering construction.
Microstructural characterization and properties of selective laser melted maraging steel with different build directions
Published in Science and Technology of Advanced Materials, 2018
Chaolin Tan, Kesong Zhou, Min Kuang, Wenyou Ma, Tongchun Kuang
When a material experiences a sudden and intense impact, it may behave in a much more brittle manner than is observed in the tensile test. We measure the energy needed to fracture a material and evaluate the brittleness as well as impact toughness of a material under high strain rates in an impact test. The impact energies and fracture morphologies of AF and heat-treated SLM specimens with both horizontal and vertical building orientations are provided in Figure 8. As observed in Figure 8(a), the impact energies of heat-treated specimens (12.32–15.38 J) are much lower than AF specimens. Because, the heat treatments increased the brittleness, less energy was needed to cause a complete rupture. Besides, one can note that SAT specimens (14.68–15.38 J) present slightly higher impact energies compared with aged specimens (12.32–13.85 J), so SAT specimen obtained a superior impact toughness in these two kinds of heat treatments. This feature is consistent with the tensile performance that solution-aged specimens achieved superior tensile toughness in comparison with single aged specimens. Fracture morphologies are compared in Figure 8(b), evident lateral expansion and ductile fractures appear in AF specimens, which indicate high impact toughness. In contrast, the plain fracture surfaces almost without any plastic deformation present in the heat-treated specimens, indicating a significant increase in brittleness.