A thermally stabilized fastener system and method is disclosed. The disclosed system/method integrates a fastener (FAS) incorporating a faster retention head (FRH), fastener retention body (FRB), and fastener retention tip (FRT) to couple a mechanical member stack (MMS) in a thermally stabilized fashion using a fastener retention receiver (FRR). The MMS includes a temperature compensating member (TCM), a first retention member (FRM), and an optional second retention member (SRM). The TCM is constructed using a tailored thermal expansion coefficient (TTC) that permits the TCM to compensate for the thermal expansion characteristics of the FAS, FRM, and SRM such that the force applied by the FRH and FRR portions of the FAS to the MMS is tailored to a specific temperature force profile (TFP) over changes in MMS/FAS temperature. The TCM may be selected with a TTC to achieve a uniform TFP over changes in MMS/FAS temperature.

A connecting element (1, 11) has a connecting part (2, 12) which has a thread (3, 13), wherein the thread (3-13) comprises a nominal diameter (d), a flank diameter (d.sub.2), a pitch (S.sub.ges), and —thread turns (n.sub.ges), wherein the pitch (S.sub.ges) of the thread (3, 13) is made up of a first pitch (S.sub.norm) and of a second pitch (S.sub.diff), wherein the first pitch is a standard pitch (S.sub.norm), in particular corresponding to the nominal diameter (d), and wherein the second pitch (S.sub.diff) corresponds to an amount of elastic and/or plastic extension under strain (f, fz) of the threaded connecting part (2, 12), wherein the extension under strain (f, fz) occurs in a predetermined operating state of the threaded connecting element (1, 11).

A connecting element (1, 11) has a connecting part (2, 12) which has a thread (3, 13), wherein the thread (3-13) comprises a nominal diameter (d), a flank diameter (d.sub.2), a pitch (S.sub.ges), and —thread turns (n.sub.ges), wherein the pitch (S.sub.ges) of the thread (3, 13) is made up of a first pitch (S.sub.norm) and of a second pitch (S.sub.diff), wherein the first pitch is a standard pitch (S.sub.norm), in particular corresponding to the nominal diameter (d), and wherein the second pitch (S.sub.diff) corresponds to an amount of elastic and/or plastic extension under strain (f, fz) of the threaded connecting part (2, 12), wherein the extension under strain (f, fz) occurs in a predetermined operating state of the threaded connecting element (1, 11).

A fastening structure (105) includes a pair of fastening members (105A) joined to each other, which is coupled with a bolt. The fastening member (105) is made of steel. A surface other than joint surfaces (Sa) has a Rockwell hardness of 50 HRC or more. The joint surfaces (Sa) have a Rockwell hardness of 30 HRC or more and less than 50 HRC. The joint surfaces (Sa) have an arithmetic mean roughness (Ra) of 0.2 μm or more and 0.5 μm or less. Production cost is suppressed, and at the same time, bending fatigue strength is secured and secondary damage due to abrasion powder generated by fretting is prevented.

The present invention discloses methods and systems for detecting the health status of a bolt which fastens a rotor blade of a wind turbine. Values of the axial stress/strain of the bolt and motion and orientation data are acquired in different aerial orientations. Values of the prestress/strain and load-stress/strain are obtained using the values of the axial stress/strain and the motion and orientation data. Values of the prestress/strain and load-stress/strain are compared with the reference values. The health status of the bolt, rotor blade, and the wind turbine system is determined based on the comparison results. The method is noninvasive and doesn't affect the function and performance of the bolt and the turbine system.

A stay rod assembly for a fluid pump has a rod with the first threaded section at one end and a second threaded section at an opposite end thereof with a stud portion located between the first threaded section and the second threaded section, and a sleeve positioned over the stud portion of the rod. The stud portion is tapered so as to narrow diameter from the first threaded section to the second threaded section. The stud portion has no shoulders thereon. The rod is received in an interior of the sleeve.

A thermally stabilized fastener system and method is disclosed. The disclosed system/method integrates a fastener (FAS) incorporating a faster retention head (FRH), fastener retention body (FRB), and fastener retention tip (FRT) to couple a mechanical member stack (MMS) in a thermally stabilized fashion using a fastener retention receiver (FRR). The MMS includes a temperature compensating member (TCM), a first retention member (FRM), and an optional second retention member (SRM). The TCM is constructed using a tailored thermal expansion coefficient (TTC) that permits the TCM to compensate for the thermal expansion characteristics of the FAS, FRM, and SRM such that the force applied by the FRH and FRR portions of the FAS to the MMS is tailored to a specific temperature force profile (TFP) over changes in MMS/FAS temperature. The TCM may be selected with a TTC to achieve a uniform TFP over changes in MMS/FAS temperature.

A thermally stabilized fastener system and method is disclosed. The disclosed system/method integrates a fastener (FAS) incorporating a faster retention head (FRH), fastener retention body (FRB), and fastener retention tip (FRT) to couple a mechanical member stack (MMS) in a thermally stabilized fashion using a fastener retention receiver (FRR). The MMS includes a temperature compensating member (TCM), a first retention member (FRM), and an optional second retention member (SRM). The TCM is constructed using a tailored thermal expansion coefficient (TTC) that permits the TCM to compensate for the thermal expansion characteristics of the FAS, FRM, and SRM such that the force applied by the FRH and FRR portions of the FAS to the MMS is tailored to a specific temperature force profile (TFP) over changes in MMS/FAS temperature. The TCM may be selected with a TTC to achieve a uniform TFP over changes in MMS/FAS temperature.

A steel for a high-strength bolt that includes from 0.50 mass % to 0.65 mass % carbon, from 1.5 mass % to 2.5 mass % silicon, 1.0 mass % or more chromium, 0.4 mass % or less manganese, greater than 1.5 mass % molybdenum, 0.03 mass % or less phosphorus and sulfur combined, and balance iron and inevitable impurities.

A steel for a high-strength bolt that includes from 0.50 mass % to 0.65 mass % carbon, from 1.5 mass % to 2.5 mass % silicon, 1.0 mass % or more chromium, 0.4 mass % or less manganese, greater than 1.5 mass % molybdenum, 0.03 mass % or less phosphorus and sulfur combined, and balance iron and inevitable impurities.