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Materials
Published in Sumit Sharma, Composite Materials, 2021
Composite materials made from low-modulus carbon fibers, typically, have a high shear strength. Compared to high-modulus fibers, these types of fibers show superior bonding ability with resins. It is believed that this behavior is a direct result of the presence of an isotropic surface layer of carbon on the low-modulus carbon fibers. The fundamental structural units of these fibers are small and have a layered structure, but are randomly oriented. Therefore, a large portion of the fiber surface will consist of exposed layer edges uniformly distributed over the surface. The exposed edges are believed to be highly reactive and may even bond chemically with epoxy resins. In contrast, high-modulus carbon fibers are more ordered due to graphitization and orientation of the crystallites during manufacture. The surface is anisotropic, consisting of relatively large areas of exposed crystallite basal planes and little exposure of edges.
Components
Published in William Bolton, Engineering Science, 2020
The shear strength of a material is the maximum shear stress that the material can withstand before failure occurs. Every time a guillotine is used to crop a material, shear stresses are being applied at a value equal to the maximum shear stress for that material (Figure 22.12). The area over which the shear forces are being applied is the cross-sectional area of the plate being cropped.
Shear flexural behaviour of high strength concrete beams
Published in Sheela Evangeline, M.R. Rajkumar, Saritha G. Parambath, Recent Advances in Materials, Mechanics and Management, 2019
Beams are one of the most important parts of any concrete structure. The beams carry loads from slabs to columns. Flexural strength is the ability of a beam or slab to resist failure in bending. Shear strength is the ability of the material to resist the shear load. A shear load is a force that tends to produce a sliding failure on material along a plane that is parallel to the direction of force. The shear strength of reinforced concrete (RC) beams is contributed by the aggregate interlock mechanism, the compression shear zone, and the dowel action of longitudinal reinforcement in the tension zone.
Microstructure and shear strength evolution of a lime-treated clay for use in road construction
Published in International Journal of Pavement Engineering, 2020
Marco Rosone, Clara Celauro, Alessio Ferrari
SEM microphotographs at low magnification (100x) of samples treated with 2% and 6% of lime 1 year after treatment (Figure 7(a,b)) highlight some peculiar characteristics of enhanced microstructures. Macropores in the order of 15–20 μm and long fissure-like pores having width of 3–10 μm between aggregate contacts are clearly visible in the clay treated with 2% of lime. On the other hand, the microstructure of clay treated with 6% of lime is characterised by aggregates with well-defined physical boundaries and intensely interlocked with one another similarly to what happens in calcareous, quartz and pumice sands subjected to very high stresses (e.g. Valore and Ziccarelli 2009; Ziccarelli 2016). This microstructural configuration can contribute to increasing the shear strength.
An overview of microstructural and material properties of ultra-high-performance concrete
Published in Journal of Sustainable Cement-Based Materials, 2019
The capacity of a material to resist the structural failure or yield in shear is called the shear strength of that material. UHPC are much better in shear resistance as compared to normal strength or high strength concrete (NSC/HSC). Hussein and Amleh [122] concluded in their study of UHPC’s structural behavior that the ultimate shear strength of UHPC was higher than NSC/HSC. Generally, UHPC show a very complex behavior under shear loading. The main factors behind the shear failure of a structure are shearing forces along with bending moments. The resistance to these shear failures is directly proportional to the volume of fibers incorporated in the mix, whereas inversely proportional to the ratio of shear span to depth [131]. There is a huge decrement of about 67% in the shear strength of UHPC having 1.5% fiber incorporation due to increase of 0.7 in the shear span to depth ratio. According to Ngo et al. [131], the shear stress–strain curve before the point of first shear cracking shows a linear change whereas a non-linear response up to ultimate shear strength has been observed afterwards (Figure 12). However, a ductile nature has been observed due to the addition of fibers. The experimental results also demonstrated that the shear strength of UHPC was always greater than its tensile strength. The shear strength of 1.5% fiber mixed UHPC was found ∼1.6 times greater than its tensile strength.
Temperature-dependent mechanical properties of defective graphene reinforced polymer nanocomposite
Published in Mechanics of Advanced Materials and Structures, 2021
Rui Sun, Lili Li, Shaoyu Zhao, Chuang Feng, Sritawat Kitipornchai, Jie Yang
It is well perceived that temperature plays a significant role in the mechanical properties of the pristine graphene and graphene reinforced nanocomposites [19–24]. Zhang et al. [19] reported that mechanical properties including the Young’s modulus, fracture strength and strain of graphene have a linear degradation relationship with increasing temperature up to 2000K. Lin et al. [20] performed an investigation on the temperature-dependent mechanical properties of graphene/PMMA nanocomposite at the atomic scale by using MD simulation and found that both Young’s modulus and shear modulus of nanocomposite become more sensitive to temperature variation as the graphene volume fraction increases. Min et al. [21] studied the shear properties of graphene using MD simulations at different temperatures. Results showed that the shear strength and strain decrease at a higher temperature, but the shear modulus increases as the temperature increases up to 800K then decreases as temperature further increases. Ramirez et al. [22] reported an experimental study on the thermal and magnetic properties of nanostructured ferrimagnetic iron oxide composites with graphene and graphite fillers synthesized via the current activated pressure assisted densification and demonstrated that the thermal conductivity can be considerably increased through the addition of graphene and graphite fillers without significant degradation of magnetization. Zhao et al. [23] investigated effects of temperature, strain rate, and structural defects on the tensile properties of a single layer graphene along the armchair direction through MD simulation and found that Young’s modulus, fracture strength, and strain decrease as temperature increases from 300 to 2400K. It also reported that the fracture strength and stain are more sensitive to temperature than to strain rate and atomic defects.