tensile strength by its tensile stress area, As Determining the strength of the threads is more complicated. The equation to calculate the thread stress area in ASTM F606-95b if found in paragraph 3.4.2, equation (1): A= 0.7854[D- (0.9743)/n]squared In the 26th Edition of Machinery Handbook, Page 1490, a topic: "Formulas for stress areas and lengths of engagement of screw threads" The above equation is given as Eq. The bolt thread shear area per inch (AS s) 5. 2a, for steels of up to 100,000 psi ultimate tensile strength, and Eq. The stressed area in a bolt can be calculated as. Thread: Nominal stress area mm²: Property class: 4.6: 4.8: 5.6: 5.8: 6.8: 8.8: 9.8: 10.9: 12.9: Min. The weakest points in a bolt is the stressed area in the thread root. The shear area of the internal thread (hole) Tensile stress area of the external thread (bolt) For steels of up to 100,000 psi ultimate tensile strength, the tensile stress area of the bolt thread At is. Don't be confused with Root area - a more conservative stress area that is still widely used such as in ASME B31.1 code. The critical areas of stress are as follows: tensile stress area of the bolt, stress area of the male thread, and stress area of the female thread. Tensile Stress Area of an external thread ( fastener, screw ) Where: A t = Tensile Stress Area D = Major Diameter. Since the male threads pull past the female threads, or vice-versa, the threads fail in shear and not in tension. 3. UN and UNR Bolts Tensile Stress Area. where. en-84-13 lnl stress analysis on screw thread a. r. yao and j. a. doran0 august 1984 luu engieerig drectrat rokiln rok linis629-50san, rea 85 09 2 0 4,,, The tensile stress area (A s) 4. getcalc.com's Tensile Stress Area of Bolt Calculator is an online mechanical engineering tool to calculate the tensile (critical) stress area or the mimimum area of threaded section of the bolt, in both US customary & metric (SI) units. Root area is based on the root or minor diameter of the threads, and therefore its stress area is smaller than the tensile stress area. A = (π / 4) (d n - … The stressed area depends on the type of threads - coarse threads reduces the stressed area compared to fine threads. The shear area of the internal thread (nut, tapped hole) When a reliable design is to be achieved screw joints are such designed that the effective cross section area is determinative for the strength of the assembly, i.e. the screw fails rather than the internal or external thread strips. Thread Tensile Stress Area (At) = Automatic recalculation. D = basic major diameter of the thread (in) n = number of threads per inch. 2b: The internal thread shear area per inch (AS n) 6. Therefore, the stripping strength of an assembly depends on the shear strength of the nut and bolt materials. D = nominal diameter, P = thread pitch, n = threads per inch, PI = 3.1416.