Browse Topic: Tensile strength
Metastable β-titanium alloys have attracted considerable interest for structural applications, owing to their superior specific strength and the ability to obtain enhanced ductility through phase transformations induced by deformation. Nevertheless, in recently developed Ti-Zr-Al-V alloy systems, the interactions among dislocation slip, strain-induced martensitic transformation, and the consequent work-hardening response remains largely unclear. Under room-temperature uniaxial tension, this work systematically investigates how the microstructure evolves and how the alloy deforms for a metastable β-type Ti-42Zr-12Al-4V (at.%) alloy. To track the progression of strain-induced α″ martensite and dislocation activity across varying strain levels, techniques including quasi-in-situ scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and focused ion beam (FIB) were employed. Findings indicate that the dominant strengthening mechanism stems from the strain-induced α″ martensite blocking dislocation motion, alongside dislocation cross-slip. Although the martensite volume fraction rises with increasing strain, its growth rate diminishes at higher strains. The martensite and the β matrix exhibited a clear Burgers-type orientation relationship, namely [001]α″//[110]β. Moreover, the appearance of martensite inside both primary and secondary slip bands generates a dynamic Hall-Petch effect, which reduces the dislocation mean free path and thereby supports continued strain hardening. These results provide deeper insight into the transformation-induced plasticity (TRIP)-assisted deformation mechanisms active in β-type titanium alloys and could guide the development of strong yet ductile materials.
Due to their high specific modulus and specific strength, carbon fiber reinforced polymer (CFRP) composites have been widely adopted in the aviation field. However, CFRP components produced by conventional vacuum assisted resin transfer molding (VARTM) often exhibit defects such as Pores and dry spots. To address these limitations, this study develops a large-area, highly uniform vibration-assisted VARTM (UAVR) system and conducts ultrasound-assisted experiments. The results demonstrate that ultrasonic treatment at various frequencies consistently improves moulding uniformity. In particular, when the ultrasound frequency is 22 kHz, the tensile strength increases by up to 13.23%, and the compressive strength increases by up to 8.48%. This study has practical significance for improving the performance of CFRP.
Live-line operation is a critical technique for maintaining the reliability and continuity of power supply in modern distribution networks. Insulating mats serve as essential protective equipment during such operations by providing both electrical insulation and mechanical shielding. In practical service conditions, insulating mats are subjected to repeated mechanical contact and friction against conductors, metallic fittings, and ground surfaces, which progressively deteriorates their surface integrity and compromises operational safety. Current performance standards for insulating mats emphasize dielectric and tensile properties, while tribological durability remains unaddressed. In this study, an EVA – PA6 composite film fabricated via the tape casting method was selected as the representative outer insulating layer of insulating mats. Reciprocating friction tests were conducted using an SDR339 abrasion tester to evaluate the effects of normal load and sliding speed on wear behavior. The results indicate that wear mass increased monotonically with friction cycles at a given speed, whereas the incremental wear rate gradually decreased due to contact area evolution. A pronounced transition from mild surface abrasion to severe material removal was observed when the applied load reached 5 N, accompanied by surface scratching and exposure of the internal fibrous layer. These findings demonstrate that the wear resistance of the EVA – PA6 composite film is insufficient for long-term service under realistic frictional conditions. The results provide experimental evidence supporting the necessity of incorporating standardized wear resistance evaluation into performance criteria for insulating mats used in live-line operations.
This Purchasing Specification, AMS6885/3, specifies the batch release and delivery requirements for unidirectional carbon fiber tape epoxy prepreg used for repair. This specification is applicable only when the unidirectional carbon fiber tape epoxy prepreg is used as part of the repair system defined in AMS6885 and AMS6885/1. This specification also defines the procedure and requirements for storage life extension of materials purchased against this specification. It is only applicable for materials qualified against AMS6885 (refer to PRI-QPL-AMS6885) and shall be carried out within the responsibility of the purchaser and under control of its Quality organisation.
This Technical Specification gives information about technical requirements and qualification procedures of adhesive paste with or without thickening agent for core restoration of aircraft components.
Foam material models for automotive structural analysis typically require tensile and compressive data at multiple strain rates. The testing is costly and may require a long time to complete. For many applications, foams of similar chemistry are used and the foam structural responses, such as stiffness and compression force deflection, are controlled by the foam density. In such cases, Machine Learning (ML) lends itself as an ideal tool to detect the trends in material response based on density and strain rate. In this paper, two sets of polyurethane (PU) foams of different densities were tested at four strain rates ranging from 0.01/s to 100/s. ML models capable of predicting compressive stress-strain response for a range of densities were developed. The models demonstrated good prediction capability for intermediate strain rates at all foam densities and in extrapolating stress-strain curves at higher densities at all strain rates. The strain rate trends for density outside of the training data set were also correctly predicted by the models. This demonstrated that ML tools can successfully be used to estimate material stress-strain response thus significantly reducing the testing cost and time.
Aluminum alloy wheels have become the preferred choice over steel wheels due to their lightweight nature, enhanced aesthetics, and contribution to improved fuel efficiency. Traditionally, these wheels are manufactured using methods such as Gravity Die Casting (GDC) [1] or Low Pressure Die Casting (LPDC) [2]. As vehicle dynamics engineers continue to increase tire sizes to optimize handling performance, the corresponding increase in wheel rim size and weight poses a challenge for maintaining low unsprung mass, which is critical for ride quality. To address this, weight reduction has become a priority. Flow forming [3,4], an advanced wheel rim production technique, which offers a solution for reducing rim weight. This process employs high-pressure rollers to shape a metal disc into a wheel, specifically deforming the rim section while leaving the spoke and hub regions unaffected. By decreasing rim thickness, flow forming not only enhances strength and durability but also reduces overall wheel weight. This study investigates and compares the mechanical properties of conventional GDC and LPDC cast alloy wheels with flow-formed counterparts, focusing on the rim region. Results reveal that the flow-forming process facilitates a 30% thickness reduction in the rim section. Furthermore, it leads to a slight increase in yield and tensile strength while significantly improving elongation in parallel to the flow-forming direction. The study also examines microstructural changes, including the deformation behavior of silicon dendrites [5].
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