Abstract: A vehicle roof stiffener includes at least one fiber reinforced polymer (FRP) portion and at least one metal or metal alloy portion. The FRP portion includes at least one transition structure including a metal or a metal alloy. At least some of the fibers of the FRP portion are embedded in the transition structure. The metal or metal alloy portion is secured to the transition structure of the FRP portion. In an example vehicle roof stiffener, the metal portion extends parallel to a longitudinal axis of a vehicle, and the FRP portion extends transverse to the longitudinal axis. The example vehicle roof stiffener may include a front FRP portion, a rear FRP portion, and two metal side portions. The metal side portions and the FRP portions may be joined by welding the transition structures to the metal portions.

Abstract: A method for welding a stack of sheets having a plurality of sheets of different materials is provided. In an aspect, the stack of sheets includes an aluminum sheet and a galvanneal steel sheet. In an aspect, the method includes resistively spot welding the galvanneal sheet to a hot-stamped steel sheet placed between the aluminum sheet and the galvanneal sheet, the sheet of hot-stamped steel including stress relief sections. The method further includes placing a metal foil on the aluminum sheet and vaporizing the metal foil to project portions of the aluminum sheet through the stress relief sections of the hot-stamped steel sheet to weld the portions of the aluminum sheet to the galvanized steel sheet. In another aspect, the method includes placing the metal foil on a raised portion of the aluminum sheet and projecting the raised portion of the aluminum onto the galvanneal steel sheet.

Abstract: A vehicle roof stiffener includes at least one fiber reinforced polymer (FRP) portion and at least one metal or metal alloy portion. The FRP portion includes at least one transition structure including a metal or a metal alloy. At least some of the fibers of the FRP portion are embedded in the transition structure. The metal or metal alloy portion is secured to the transition structure of the FRP portion. In an example vehicle roof stiffener, the metal portion extends parallel to a longitudinal axis of a vehicle, and the FRP portion extends transverse to the longitudinal axis. The example vehicle roof stiffener may include a front FRP portion, a rear FRP portion, and two metal side portions. The metal side portions and the FRP portions may be joined by welding the transition structures to the metal portions.

Abstract: A vehicle roof stiffener includes at least one fiber reinforced polymer (FRP) portion and at least one metal or metal alloy portion. The FRP portion includes at least one transition structure including a metal or a metal alloy. At least some of the fibers of the FRP portion are embedded in the transition structure. The metal or metal alloy portion is secured to the transition structure of the FRP portion. In an example vehicle roof stiffener, the metal portion extends parallel to a longitudinal axis of a vehicle, and the FRP portion extends transverse to the longitudinal axis. The example vehicle roof stiffener may include a front FRP portion, a rear FRP portion, and two metal side portions. The metal side portions and the FRP portions may be joined by welding the transition structures to the metal portions.

Abstract: A method for welding a stack of sheets having a plurality of sheets of different materials is provided. In an aspect, the stack of sheets includes an aluminum sheet and a galvanneal steel sheet. In an aspect, the method includes resistively spot welding the galvanneal sheet to a hot-stamped steel sheet placed between the aluminum sheet and the galvanneal sheet, the sheet of hot-stamped steel including stress relief sections. The method further includes placing a metal foil on the aluminum sheet and vaporizing the metal foil to project portions of the aluminum sheet through the stress relief sections of the hot-stamped steel sheet to weld the portions of the aluminum sheet to the galvanized steel sheet. In another aspect, the method includes placing the metal foil on a raised portion of the aluminum sheet and projecting the raised portion of the aluminum onto the galvanneal steel sheet.

Abstract: A vehicle roof stiffener includes at least one fiber reinforced polymer (FRP) portion and at least one metal or metal alloy portion. The FRP portion includes at least one transition structure including a metal or a metal alloy. At least some of the fibers of the FRP portion are embedded in the transition structure. The metal or metal alloy portion is secured to the transition structure of the FRP portion. In an example vehicle roof stiffener, the metal portion extends parallel to a longitudinal axis of a vehicle, and the FRP portion extends transverse to the longitudinal axis. The example vehicle roof stiffener may include a front FRP portion, a rear FRP portion, and two metal side portions. The metal side portions and the FRP portions may be joined by welding the transition structures to the metal portions.

Abstract: A method for welding a stack of sheets having a plurality of sheets of different materials is provided. In an aspect, the stack of sheets includes an aluminum sheet and a galvanneal steel sheet. In an aspect, the method includes resistively spot welding the galvanneal sheet to a hot-stamped steel sheet placed between the aluminum sheet and the galvanneal sheet, the sheet of hot-stamped steel including stress relief sections. The method further includes placing a metal foil on the aluminum sheet and vaporizing the metal foil to project portions of the aluminum sheet through the stress relief sections of the hot-stamped steel sheet to weld the portions of the aluminum sheet to the galvanized steel sheet. In another aspect, the method includes placing the metal foil on a raised portion of the aluminum sheet and projecting the raised portion of the aluminum onto the galvanneal steel sheet.

Abstract: Crashworthiness designing of a structure using a Hybrid Cellular Automata (HCA) algorithm where field states are computed using finite element analysis (FEA) and the material distribution of the structure is updated at each iteration using cellular automata method. The HCA algorithm optimizes the topology of the structures to achieve certain performance within the limits of various constraints applied to ensure crashworthiness of the structures. The HCA algorithm may also be applied to designing of structures to be fabricated by an extrusion method having the same cross section along the direction of extrusion or stamped structures having thickness varying across the structure.

Abstract: Crashworthiness designing of a structure using a Hybrid Cellular Automata (HCA) algorithm where field states are computed using finite element analysis (FEA) and the material distribution of the structure is updated at each iteration using cellular automata method. The HCA algorithm optimizes the topology of the structures to achieve certain performance within the limits of various constraints applied to ensure crashworthiness of the structures. The HCA algorithm may also be applied to designing of structures to be fabricated by an extrusion method having the same cross section along the direction of extrusion or stamped structures having thickness varying across the structure.