Comparison of the Mechanical Behavior of Filamentary Reinforced Aluminum and Titanium Alloys

Abstract

The tensile behavior, erosion/impact resistance, mechanical fatigue strength, thermal fatigue behavior, and creep strength of filamentary reinforced aluminum and titanium alloy matrix composites were briefly compared. Parallel to the filament direction, aluminum matrix composites are slightly stronger than titanium matrix composites up to a temperature of about 600°F (314°C). Titanium matrix composites, however, have shown significant off-axis strength advantage even at room temperature. B/SiC-Ti has shown a five-fold advantage in transverse strength over B-A1 at a test temperature of 500°F (260°C). The erosion rate of fiber-reinforced composites was found to be controlled by the matrix until the filaments became exposed. The titanium matrix, having an order-of-magnitude stronger matrix yield strength, exhibited greatly improved ballistic impact resistance, when compared to the aluminum matrix system. The low-cycle fatigue strength of titanium composite was superior to that of comparable aluminum composite. On the other hand the high-cycle fatigue strength in the 0 deg orientation for the titanium composite was significantly lower than that of a comparable aluminum composite. The resistance to thermal fatigue damage, when measured by tensile strength degradation, delamination, and dimensional distortion, was in favor of titanium composites. The transverse creep strength of B/SiC at 800°F (427°C) was shown to be ten times better than that of B/SiC-A1 at 575°F (302°C).

Analytic hierarchy process methodology in part selection for fused deposition modelling in the South African railway industry

“…Toth and Vilakazi 8 investigated the feasibility of using the FDM process to 3D print design optimised grease plate brackets. These brackets are used to support the grease plates to the rail gauge, and a material change was investigated due to increased theft and vandalism.…”

“…Past case studies have shown the benefit of AM within the railway environment for light-weighting, assembly-part consolidation, spare parts, material change, prototypes and new designs. 1,4,[7][8][9] Identifying and selecting parts that will benefit from the AM process, particularly the Fused Deposition Modelling (FDM) technology for the railway environment, depends on several factors considered at the conceptual design stage. 7 Part size and printer parameters such as build volume limit the production to specific parts and components.…”

“…The influence of printing parameters and technical characteristics affect the mechanical performance of as-printed parts. 8,[10][11][12][13] In the case of material properties, the FDM process is limited to selecting polymer materials and metal-polymer materials, which requires sintering to produce final parts, and the printer's capabilities must be factored into the decisionmaking process at the conceptual design stage. [14][15][16] Finally, the environmental characteristics of as-printed parts must be considered prior to operating in the railway environment.…”

“…Figure 3. Wayside lubricator (a) lubricator tooling (b-d) replacement grease plate brackets (e) prototype weather station (f) [7][8][9]. …”

Using Topology Optimisation to Influence the Infill Placement of Fused Deposition Modelled Parts

“…In the AM sector, topology optimisation (TO) techniques and algorithms are a standard method that designers use to improve strength-to-weight performance and to reduce the costs of 3D-printed parts, which are typically manufactured using powderbased AM technologies [4]. In comparison, the use of TO techniques for the FDM technology for internal (infill) and external structures remains relatively immature and not fully adopted [5], [6], [7]. Commercial and open-source slicing software packages for FDM technologies use traditional 2D infill geometries and infill density scaling to 3D-print the internal contours of a part.…”