ASME PTB-5-2013 pdf download
ASME PTB-5-2013 pdf download.Section VIII – Division 3 Example Problem Manual.
3 EXAMPLE PROBLEMS MATERIALS 3.1 Example Problem E-KM-2.1.1 – Evaluation of Test Locations for Cylindrical Forgings in Accordance with KM-2 This problem presents an evaluation of requirements for the minimum number, location and type of tests required for the following two cases: Material dimensions Case 1 – 12 in. diameter x 18 in. long and Case 2 – 12 in. diameter x 15 ft. long (180 in.) The forgings are SA-723 Grade 2 Class 2 material with a minimum specified yield strength of 120,000 psi and a minimum specified tensile strength of 135,000 psi. The forgings are all solid cylinders and all tests are to be taken from test material on the end of the cylinders, which when remove, will leave the size of material listed in each of the cases. STEP 1 – Determine the thickness of the forging at heat treat (KM-201.2 / KM-211.2) The thickness of the forging is defined as: Case 1 – This is a cylindrical forging which the thickness is equal to the diameter of the forging or 12 inches (T = 12 in). Case 2 – This is a cylindrical forging which the thickness is equal to the diameter of the forging or 12 inches (T = 12 in). STEP 2 – Determine the location of the “datum point” for the forgings (KM-211.2) The datum point is either the mid-point of the tension test specimen or the area under the notch of the impact test specimens. This datum will be used for all of the specimens including both the tension and Charpy specimens. Case 1 – The datum point is located at a position of T/4 or 3 inches from the OD of the cylinder and 2T/3 or 8 inches from the end of the cylinder. Tensile samples shall be longitudinal and CVN samples shall be transverse. Case 2 – The datum point is located at a position of T/4 or 3 inches from the OD of the cylinder and 2T/3 or 8 inches from the end of the cylinder with a 180° offset between the test locations on each end. STEP 3 – Determine the minimum number test specimens required Case 1 – The overall dimensions of this forging at the time of heat treatment is: Diameter = 15 in diameter Length = 27 inches. Therefore, the weight of the 15 inch diameter x 27 inch long forging is approximately 1400 lb. Per KM-231(b), this means that the piece will require one tension test and one set of three Charpy V-notch specimens per component. Case 2 – The weight of this forging is in excess of 5000 lb and it is in excess of 80 inches long. Therefore, KM-231(c) requires that two tension tests and two sets of Charpy V-notch impact tests be taken at a datum point from each end of the forging 180 degrees apart. Therefore, for each forging, four tension tests (two from each end) and four sets of three impact specimens (two sets from each end) shall be taken from the forging.
c) STEP 3 – An elastic-plastic material model shall be used in the analysis for LC # 1 global design condition. The von Mises yield function and associated flow rule should be utilized if plasticity is anticipated. A material model that includes hardening or softening, or an elastic perfectly plastic model may be utilized. A true stress-strain curve model that includes temperature dependent hardening behavior is provided in KD-231.4. When using this material model, the hardening behavior shall be included up to the true ultimate stress and perfect plasticity behavior (i.e., the slope of the stress-strain curves is zero) beyond this limit. The effects of nonlinear geometry shall be considered in the analysis. The material model for the hydrostatic test pressure case was an elastic-perfectly plastic model. The true stress-strain curve from KD-231.4 was used for the analysis. The material keywords used in the ANSYS input file are shown below. See problem E-KD-2.2.4 for an example of the generation of a typical stress-strain curve using this method.
