Staked Fastener Cold Heading, Installation and Pull Test Simulation
A DEFORM-2D simulation modeled the multi-station cold heading, mechanical joining installation and "pull-out" performance testing of a "drawform stud" staked fastener product.
Product: DEFORM Premier; DEFORM-2D
Courtesy: Whitesell Corp.
Summary:
The Fabristeel Corporation utilized DEFORM-2D to predict the mechanical joint strength of a "drawform stud" staked fastener. Drawing, forming, installation and "pull test" performance operations were studied. The entire process chain was modeled in the DEFORM-2D Multiple Operation environment. Once the workflow was defined, the entire chain was simulated, automatically, from start to finish with no user intervention. The mechanical joint strength, predicted prior to production, was within 10% of the actual result. The pull test results were 15% more accurate by accounting for the full manufacturing process history in the product performance analysis.
Case Study:
The development of complex forming processes such as self-penetrating fasteners, staked studs and rivets involve complexities over and above traditional forming operations. In these applications, the interactions among multiple plastic deforming bodies need to be considered. Unlike forming with hard dies, the forming surface for any object is a ‘moving target’. Another consideration is that the installation is influenced by plastic strain (work hardening) induced during cold forming operations. Therefore, it isn’t practical to perform installation trials with machined blanks.
The Fabristeel Corporation of Taylor, Michigan used computer simulation to develop their self-piercing mechanically staked fasteners for sheet metal parts. The patented drawform stud was fully developed using simulation. The development process included cold forming the stud, an installation process and a pullout test. The entire manufacturing process was developed with the aid of process simulation. Based on damage values in the sheet, the original design was modified to prevent fracture in the panel.
Pullout loads are one of the acceptance criteria for this type of part.
A failed pullout test requires the designers to go back to the drawing board. The pullout loads predicted by DEFORM were within 5% of experimental values. Such accuracy was not possible without capturing the strain from the cold forming process.
By comparison, an installation and pull test were simulated on a part with no prior strain. This replicated physical testing of a machined stud. Simulation results indicated a different uninstalled stud shape and a 15% reduction in joint strength. This supported the stance that machined prototypes were not a suitable replacement for cold formed parts in performance testing.
Mechanical joining simulations such as this are not possible without the ability to model multiple deforming objects in a very complex forming operation. DEFORM is routinely used to model such phenomena.
Смотрите видео Staked Fastener Cold Heading, Installation and Pull Test Simulation онлайн без регистрации, длительностью часов минут секунд в хорошем качестве. Это видео добавил пользователь SFTC DEFORM 09 Апрель 2021, не забудьте поделиться им ссылкой с друзьями и знакомыми, на нашем сайте его посмотрели 5,22 раз и оно понравилось 3 людям.