For friction stir lap welding (FSLW) process by the rotating pin greatly inserting into the bottom plate, the bending-down morphology of hook helps to obtain a high-strength lap joint, and can be more conducive to the...For friction stir lap welding (FSLW) process by the rotating pin greatly inserting into the bottom plate, the bending-down morphology of hook helps to obtain a high-strength lap joint, and can be more conducive to the joint strength when the tensile-fractured path is located in the top plate. In light of this, the reverse-flow FSLW (RF-FSLW) by a newly designed rotating tool with a right-left threaded X-shape pin (X-pin) was employed to weld 2024-T4 aluminum alloys with the same plate thickness, and the flow field simulation, in situ tensile test and EBSD analysis were utilized to understand the relations among the formation features, the fracture features and the joint strengths. The results indicated that under the integrated effects of the bending-down shape of hook, the bulging shape of nugget zone (NZ) and the bending-up shape of beginning part of cold lap near NZ outline, the RF-FSLW joint was tensile fractured in the top plate of joint. For the RF-FSLW joint, its maximum tensile strength was 412 MPa, and the corresponding joint efficiency (92.8%) was larger than that of reported friction stir welded joint of 2024 aluminum alloys in T temper condition. The RF-FSLW technology by the right-left threaded X-pin puts forward an extremely effective way for obtaining the superb-strength lap joint of aluminum alloys.展开更多
The effect of the rotation of the earth, this non-inertial system, has beenneglected in the theories of evolution. In this article, we put forward the hypothesis thatthe Coriolis force due to the rotation of the earth...The effect of the rotation of the earth, this non-inertial system, has beenneglected in the theories of evolution. In this article, we put forward the hypothesis thatthe Coriolis force due to the rotation of the earth is the primary cause of the right-leftasymmetry of body structures of the vertebrate. Theoretical deductions were made andcompared with available observations. Generally we found no contradiction. Afterwardsways for further validation are discussed.展开更多
基金supported by the National Natural Sci-ence Foundation of China(Nos.52074184 and 52374393)the Natu-ral Science Foundation Project of Liaoning Province(No.2023-MS-238)+1 种基金Liaoning Revitalization Talents Program(No.XLYC2203009)the Fundamental Research Funds for the Universities of Liaon-ing Province.
文摘For friction stir lap welding (FSLW) process by the rotating pin greatly inserting into the bottom plate, the bending-down morphology of hook helps to obtain a high-strength lap joint, and can be more conducive to the joint strength when the tensile-fractured path is located in the top plate. In light of this, the reverse-flow FSLW (RF-FSLW) by a newly designed rotating tool with a right-left threaded X-shape pin (X-pin) was employed to weld 2024-T4 aluminum alloys with the same plate thickness, and the flow field simulation, in situ tensile test and EBSD analysis were utilized to understand the relations among the formation features, the fracture features and the joint strengths. The results indicated that under the integrated effects of the bending-down shape of hook, the bulging shape of nugget zone (NZ) and the bending-up shape of beginning part of cold lap near NZ outline, the RF-FSLW joint was tensile fractured in the top plate of joint. For the RF-FSLW joint, its maximum tensile strength was 412 MPa, and the corresponding joint efficiency (92.8%) was larger than that of reported friction stir welded joint of 2024 aluminum alloys in T temper condition. The RF-FSLW technology by the right-left threaded X-pin puts forward an extremely effective way for obtaining the superb-strength lap joint of aluminum alloys.
文摘The effect of the rotation of the earth, this non-inertial system, has beenneglected in the theories of evolution. In this article, we put forward the hypothesis thatthe Coriolis force due to the rotation of the earth is the primary cause of the right-leftasymmetry of body structures of the vertebrate. Theoretical deductions were made andcompared with available observations. Generally we found no contradiction. Afterwardsways for further validation are discussed.
