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ASTM A325 is an ASTM International standard for heavy hex structural bolts, titled Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength. It defines mechanical properties for bolts that range from 1 ⁄ 2 to 1 + 1 ⁄ 2 inches (13 to 38 mm) in diameter. [1]
In general: ductile materials (e.g. aluminum) fail in shear, whereas brittle materials (e.g. cast iron) fail in tension (see: Tensile strength). To calculate: Given total force at failure (F) and the force-resisting area (e.g. the cross-section of a bolt loaded in shear), ultimate shear strength is:
ISO 898 is an international standard that defines mechanical and physical properties for metric fasteners.This standard is the origin for other standards that define properties for similar metric fasteners, such as SAE J1199 and ASTM F568M. [1]
Torque charts are available to specify the required torque for a given fastener based on its property class (fineness of manufacture and fit) and grade (tensile strength). Spring Analogy for a Bolted Joint. When a fastener is tightened, a tension preload is develops in the bolt, while an equal compressive preload forms in the clamped parts.
ASTM A490 and ASTM A490M are ASTM International standards for heavy hex structural bolts made from alloy steel.The imperial standard is officially titled Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength, while the metric standard (M) is titled Standard Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural ...
Bolts are correctly torqued to maintain the friction. The shear force only becomes relevant when the bolts are not torqued. A bolt with property class 12.9 has a tensile strength of 1200 MPa (1 MPa = 1 N/mm 2 ) or 1.2 kN/mm 2 and the yield strength is 0.90 times tensile strength, 1080 MPa in this case.
The formula to calculate average shear stress τ or force per unit area is: [1] =, where F is the force applied and A is the cross-sectional area.. The area involved corresponds to the material face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force.
The bolts then play the role of stops: the screws endure shear stress whereas the hole endure bearing pressure. In order to increase the bearing pressure of a material, there are several factors that can be considered. One of the most effective methods is to increase the surface area of the material.