Friction welding (FW) is a high quality, nominally solid-state joining process, which produces welds of high structural integrity. Rotary friction welding (RFW) is the most commonly used form of FW, while linear friction welding (LFW) is a relatively new method being used mainly for the production of integrally bladed disc (blisk) assemblies in the aircraft engine industry. Numerous similar and dissimilar joints of structural metallic materials have been welded with RFW and LFW. In this review, the current state of understanding and development of RFW and LFW is presented. Particular emphasis is placed on the process parameters, joint microstructure, residual stresses, mechanical properties and their relationships. Finally, opportunities for further research and development of the RFW and LFW processes are identified.

No abstract

ABSTRACT:Tensile and dynamic mechanical properties of improved ultrathin polymeric films for magnetic tapes are presented. These films include poly(ethylene terephthalate) or PET, poly(ethylene naphthalate) or PEN, and aromatic polyamide (ARAMID). PET film is currently the standard substrate used for magnetic tapes; thinner tensilized-type PET, PEN, and ARAMID were recently used as alternate substrates with improved material properties. The thickness of the films ranges from 6.2 to 4.8 m.Young's modulus of elasticity, F5 value, strain-at-yield, breaking strength, and strainat-break were obtained at low strain rates by using a tensile machine. Storage (or elastic) modulus, EЈ, and the loss tangent, tan ␦, which is a measurement of viscous energy dissipation, are measured by using a dynamic mechanical analyzer at temperature ranges of Ϫ50 to 150°C (for PET), and Ϫ50 to 210°C (for PEN and ARAMID), and at a frequency range of 0.016 to 29 Hz. Frequency-temperature superposition was used to predict the dynamic mechanical behavior of the films over a 28 decade frequency range. Results show that ARAMID and tensilized films tend to have higher strength and moduli than standard PET and PEN. The rates of decrease of storage modulus as a function of temperature are lower for PET films than those for PEN and ARAMID films. Storage modulus for PEN films are higher than that for PET films at high frequencies, but this relationship reverses at low frequencies. ARAMID has the highest modulus and strength among the films in this study. The relationship between polymeric structure and mechanical properties are also discussed.

No abstract

No abstract

Friction welding (FW) is a collection of a series of friction-based solid state joining processes which can produce high quality welds of different components with either similar or dissimilar materials and has been attracting increasing attention. Due to the extreme condition encountered during FW and the highly thermomechanical coupled nature of FW, finite element methods have been widely developed to study the FW process. In the light of reasonable simplification, we developed several effective methods based on the ABAQUS environment. Initially 2D models were developed to investigate the complete FW process, where an implicit method with remeshing and map solution techniques and an explicit method with the Arbitrary Lagrangian Eulerian (ALE) adaptive mesh controls were proposed to effectively overcome the excessive element distortion by using the ABAQUS Standard and Explicit packages, respectively. In addition, a 3D model was also developed to obtain better simulation results with the help of the ALE adaptive mesh controls in the ABAQUS/Explicit package and the map solution technique in the ABAQUS/Standard package combined with the HYPERWORKS software. The experiments validate the feasibility and accuracy of the developed models.

No abstract

No abstract