Abstract: A spot welding method including: a main energization step of energizing a pair of opposing electrodes in pressure contact with both outer surfaces of a set of sheets where multiple sheet materials are stacked, thereby to cause melting between facing surfaces of the sheet materials; and a pressing variation step of, prior to the main energization step, causing a pulsation of pressing force applied to the set of sheets from the electrodes. A resin material such as an adhesive or a sealant may be interposed between the facing surfaces of at least a pair of the sheet materials. The period of the pulsation is 0.01 to 0.7 seconds. The amplitude of the pulsation is 10% to 90% with respect to a reference value of the pressing force. The set of sheets may include a first and a second steel sheet, and an aluminum alloy sheet that are stacked in order.

Abstract: A novel spot welding method for steel sheets and an aluminum alloy sheet, includes stacked sheet materials from a pair of opposing electrodes to join the sheet materials by resistance heating. The pair of opposing electrodes are in pressure contact with both outer surfaces of the sheet sets. The sheet sets include at least a first and second steel sheet, and an aluminum alloy sheet stacked in this order. A first energization step forms a molten pool between facing surfaces of the first and second steel sheets without melting the aluminum alloy sheet. A second energization step causes a melting reaction between facing surfaces of the second steel sheet and the aluminum alloy sheet. The first and second steel sheets are joined via a first nugget. The second steel sheet and the aluminum alloy sheet are joined via a second nugget including an intermetallic compound generated by the melting reaction.

Abstract: A method of manufacturing a member for fastening by joining a nut with a tubular joint portion extending from a main body formed with an internal thread to a panel with a mounting hole for the nut on an aluminum base material. The joint portion has a rotation-preventing portion with a concave and convex shaped outer peripheral surface and a guide portion extending from the rotation-preventing portion to one side. After the guide portion is inserted into the mounting hole, the nut is energized by electrodes in contact with both nut end surface sides. The nut then generates heat, and the periphery of the mounting hole is heated and softened. When the nut is pressurized with the electrodes, the rotation-preventing portion bites into the mounting hole, and the one end portion of the guide portion is swaged to become a retaining portion on one surface side of the panel.

Abstract: A metal joined body has an iron base body and an aluminum base body that are joined together via a joint layer. The joint layer has a first layer composed of a first intermetallic compound formed on the iron base body side and a second layer composed of a second intermetallic compound formed on the aluminum base body side. The first layer has one or more first protrusions that merge integrally into the iron base body and extend in a pile shape into the first intermetallic compound. The second layer may have one or more second protrusions that are composed of a second intermetallic compound and extend in a columnar shape into the aluminum base body. The first intermetallic compound may contain Al5Fe2, and the second intermetallic compound may contain Al3Fe. The total thickness of the first layer and the second layer is, for example, 2 to 15 ?m.

Abstract: A novel spot welding method for steel sheets and an aluminum alloy sheet, includes stacked sheet materials from a pair of opposing electrodes to join the sheet materials by resistance heating. The pair of opposing electrodes are in pressure contact with both outer surfaces of the sheet sets. The sheet sets include at least a first and second steel sheet, and an aluminum alloy sheet stacked in this order. A first energization step forms a molten pool between facing surfaces of the first and second steel sheets without melting the aluminum alloy sheet. A second energization step causes a melting reaction between facing surfaces of the second steel sheet and the aluminum alloy sheet. The first and second steel sheets are joined via a first nugget. The second steel sheet and the aluminum alloy sheet are joined via a second nugget including an intermetallic compound generated by the melting reaction.

Abstract: A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is ?4?t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

Abstract: An electrode tip for resistance spot welding includes a main body with tip and base portions. The tip portion has a bottomed and substantially cylindrical shape. The base portion has a substantially cylindrical shape and merges into the tip portion. The main body is made of a copper alloy such as chromium copper. The tip portion has a bottom part and a barrel part. The bottom part has a pressure-contact surface that is not recessed with respect to a workpiece to be pressed. The barrel part has a substantially cylindrical shape and merges into the bottom part. The electrode tip may have an inner diameter ratio (inner diameter of the barrel part to an outer diameter of the base portion) of 0.4 to 0.6, and may also have a bottom thickness ratio (thickness of the bottom part to the outer diameter of the base portion) of 0.15 to 0.5.

Abstract: A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is ?4?t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

Abstract: A natural frequency and a calculated mode vector are calculated by using a finite-element method models for analysis which include an object of analysis including a plurality of components and a plurality of elements which are positioned between the components of the object of analysis and indicate a boundary condition between the components, the calculated mode vector having high degree of correlation for an experimental mode vector is extracted and set to a pair, and identifying the boundary condition of the elements based on the extracted calculated mode vector and the natural frequency corresponding to the extracted calculated mode vector.

Abstract: A method of supporting a user in mechanically analyzing a performance of an object, including the steps of: graphically displaying a generalized model which is constructed as a numerical analysis model for the object such that the generalized model has been generalized with respect to at least configuration of the object, and has been specialized with respect to a function of the object; displaying an item for letting the user enter data in order to define a specialized model which is constructed as a numerical analysis model for the object by specializing the displayed generalized model with respect to the at least configuration thereof; and mechanically analyzing the performance of the object, on the basis of the specialized model defined, a numerical analysis approach predetermined in correspondence with the function of the object, and a numerical analysis condition.

Abstract: A natural frequency and a calculated mode vector are calculated by using a finite-element method models for analysis which include an object of analysis including a plurality of components and a plurality of elements which are positioned between the components of the object of analysis and indicate a boundary condition between the components, the calculated mode vector having high degree of correlation for an experimental mode vector is extracted and set to a pair, and identifying the boundary condition of the elements based on the extracted calculated mode vector and the natural frequency corresponding to the extracted calculated mode vector.

Abstract: A method of supporting a user in mechanically analyzing a performance of an object, including the steps of: graphically displaying a generalized model which is constructed as a numerical analysis model for the object such that the generalized model has been generalized with respect to at least configuration of the object, and has been specialized with respect to a function of the object; displaying an item for letting the user enter data in order to define a specialized model which is constructed as a numerical analysis model for the object by specializing the displayed generalized model with respect to the at least configuration thereof; and mechanically analyzing the performance of the object, on the basis of the specialized model defined, a numerical analysis approach predetermined in correspondence with the function of the object, and a numerical analysis condition.