A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

The faults in welding design and process every so often yield defective parts during friction stir welding (FSW). The development of numerical approaches including the finite element method (FEM) provides a way to draw a process paradigm before any physical implementation. It is not practical to simulate all possible designs to identify the...

Mesoscale process modeling of a thick pultruded composite with variability in fiber volume fraction

Pultruded fiber-reinforced polymer composites are susceptible to microstructural nonuni-formity such as variability in fiber volume fraction (V_f ), which can have a profound effect on process-induced residual stress. Until now, this effect of non-uniform V_f distribution has been hardly addressed in the process models. In...

Numerical analysis of the effect of the scan strategy on the residual stress in the multi-laser selective laser melting

The inevitably formed residual stress in the Selective Laser Melting (SLM) process leads to distortion, crack and even delamination of the workpiece. Single laser is commonly applied during SLM processing. However, its productivity is much lower than multiple lasers. In addition, the research of residual stress with multi-laser condition...

Residual stresses in thermite welded rails: significance of additional forging

The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel...

Residual stress effects on fatigue crack growth rate of mild steel S355 exposed to air and seawater environments

In this paper, the parameters of fatigue crack growth rate for Q355J2 steel exposed to air and seawater were presented using the “Paris' law” based on the stress intensity factor (SIF), J-integral, crack tip opening displacement (CTOD) and crack tip opening angle (CTOA). The residual stress of a compact tension specimen is analysed by...

The residual stress characteristics and mechanical behavior of shot peened fiber metal laminates based on the aluminium-lithium alloy

The effect of shot peen forming on the mechanical behavior of fiber metal laminates (FMLs) based on aluminium-lithium alloy was investigated to reveal the strengthening mechanism and to dispel the suspicion that shot peen forming may result in the performance deterioration of FMLs. The interlaminar, static strength and fatigue properties of...

The evolution of residual stress in rib-diaphragm joints of orthotropic steel decks subjected to thermal cutting and welding

Residual stresses change the stress ratio of fluctuating stresses, hence seriously affect the fatigue life of orthotropic steel decks (OSDs) under traffic loading. Residual stress distributions near the U rib-diaphragm joints are very complicated and need to be investigated further. In this paper, a systematic method has been proposed for...

On process-step parallel computability and linear superposition of mechanical responses in additive manufacturing process simulation

We study linearity assumptions in the transient macroscale mechanical aspect of additive manufacturing (AM) process simulation. Linearity assumptions are often resorted to in combination with calibrated inelastic deformation components to arrive at computationally tractable yet reasonably accurate AM process models. We point out that...

Residual ultimate strength of damaged seamless metallic pipelines with combined dent and metal loss

The combination damage induced by mechanical interference, in reality, is more likely to happen. In this paper, numerical models on pipes with combined dent and metal loss in terms of a notch are developed and validated through tests (diameter-to-thickness ratio D/t of test pipes around 21), capable of predicting the residual ultimate...

Airgap-based MEMS optical filters: For the ultraviolet-visible spectrum

Rolling contact fatigue in relation to rail grinding

Spalling defects of a periodic nature are sometimes observed on heat-treated pearlitic steel rails. Defect properties suggest a relationship between maintenance grinding on a regular basis and the initiation of rolling contact fatigue (RCF). In this work, the effects of maintenance grinding are investigated experimentally for both standard...

Residual Strains in Thick Thermoplastic Composites: An Experimental Approach

Thermoplastic composites are currently investigated for application in windmill turbine blades for their recyclability. A suitable manufacturing technology for these thick structures is liquid resin infusion followed by in-situ polymerisation of Anionic Polyamide-6 (APA-6). During manufacturing of thick composite structures, temperature...

An investigation of crack resistance in composite reinforced face sheets of sandwich panels

Aluminium sandwich paaiels provided with carbon-epoxy uniaxial reinforcing strips were fatigued and subsequently tested for residual strength, Although both analysis ajid fatigue tests indicate that the crack tip zone is affected onlywhen the zone is in the immediate vicinity of a stiffener the reinforcement considerably increases crack...