Browsing by Author "Mansoor, Asif"

Now showing 1 - 6 of 6
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    Instant dynamic response measurements for crack monitoring in metallic beams
    (British Institute of Non-destructive Testing, 2019-04-01) Zai, Behzad Ahmed; Khan, Muhammad A.; Mansoor, Asif; Khan, Sohaib Z.; Khan, Kamran Ahmed
    This paper investigates the interdependencies of the modal behaviour of a cantilever beam, its dynamic response and crack growth. A methodology is proposed that can predict crack growth in a metallic beam using only its dynamic response. Analytical and numerical relationships are formulated between the fundamental mode and crack growth using the existing literature and finite element analysis (FEA) software, respectively. A relationship between the dynamic response and the modal behaviour is formulated empirically. All three relationships are used to predict crack growth and propagation. The load conditions are considered the same in all of the experiments for both model development and model validation. The predicted crack growth is compared with the visual observations. The overall error is within acceptable limits in all comparisons. The results obtained demonstrate the possibility of diagnosing crack growth in metallic beams at any instant within the operational conditions and environment.
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    A novel approach for damage quantification using the dynamic response of a metallic beam under thermo-mechanical loads
    (Elsevier, 2019-12-06) Zai, Behzad Ahmed; Khan, Muhammad A.; Khan, Kamran Ahmed; Mansoor, Asif
    This paper investigates the interdependencies of crack depth and crack location on the dynamic response of a cantilever beam under thermo-mechanical loads. Temperature can influence the stiffness of the structure, thus, the change in stiffness can lead to variation in frequency, damping and amplitude response. These variations are used as key parameters to quantify damage of Aluminum 2024 specimen under thermo-mechanical loads. Experiments are performed on cantilever beams at non-heating (room temperature) and elevated temperature, i.e., 50 °C, 100 °C, 150 °C and 200 °C. This study considers a cantilever beam having various initially seeded crack depth and locations. The analytical, numerical and experimental results for all configurations are found in good agreement. Dynamic response formulation is presented experimentally on beam for the first time under thermo-mechanical loads. Using available experimental data, a novel tool is formulated for in-situ damage assessment in the metallic structures. This tool can quantify and locate damage using the dynamic response and temperature including the diagnosis of subsurface cracking. The obtained results demonstrate the possibility to diagnose the crack growth at any instant within the operational condition under thermo-mechanical loads.
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    Prediction of crack depth and fatigue life of an acrylonitrile butadiene styrene cantilever beam using dynamic response
    (ASTM International, 2019-04-10) Zai, Behzad Ahmed; Khan, Muhammad A.; Khan, Sohaib Z.; Asif, Muhammad; Khan, Kamran Ahmed; Saquib, Ahmad N.; Mansoor, Asif; Shahzad, Majid; Mujtaba, Ahmed
    n this article, a methodology is proposed that can be used to predict the crack growth and fatigue life of a cantilever beam made of Acrylonitrile Butadiene Styrene (ABS) manufactured with fused deposition modeling. Three beam configurations based on length (L = 110, 130, and 150 mm) are considered. Empirical relationships are formulated between the natural frequency and the crack growth. The analytical and experimental results are found to be in good agreement for all configurations. Using the experimental data, a global relation is formulated for the crack depth prediction. This global relation is useful for an in situ crack depth prediction with an error of less than 10 %. Later, a residual fatigue life of these specimens is compared with a metallic structure (Aluminum 1050) of similar configuration available in the literature. It is found that the ABS material has more residual fatigue life compared with the metallic structure at the same frequency drop. Based on the remaining fatigue life, ABS material can be a potential material to manufacture machine components under cyclic loads.
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    Realizing surface amphiphobicity using 3D printing techniques: A critical move towards manufacturing low-cost reentrant geometries
    (Elsevier, 2021-01-06) Shams, Hamza; Basit, Kanza; Khan, Muhammad Ali; Saleem, Sajid; Mansoor, Asif
    Amphiphobic surfaces are obtained by lowering the surface energy through changes in surface geometry. These changes can be designed on the surface, thereby altering its wettability, and in turn rendering it amphiphobic. The main geometrical entities behind this phenomenon are reentrant geometries which prevent the solid-liquid interface tension from breaking, thereby resulting in contact angles greater than 90°. The science behind modelling and manufacturing of these reentrant geometries is well established apart from manufacturing them via extrusion-based 3-Dimensional printing processes. This review paper in identifying this gap summarizes various characterization parameters for surface wettability followed by identifying the role of surface reentrant geometries to introduce superamphiphobicity in polymers. The focus of the paper then moves towards achieving amphiphobicity using 3D printing processes where the current state of research is discussed in terms of reentrant profiles and achievement of high static contact angles. Role of the most common yet rarely reported Fused Deposition Modelling technique is discussed in more detail and a preliminary investigation based on characteristics flow and printing parameters used in Fused Deposition Modelling has been presented. The surface amphiphobicity is achieved in a one-step process characterized by high static contact angles with low and high surface tension liquids owing to air entrapment in characteristic layer-by-layer deposition features obtained in Fused Deposition Modelling.
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    Scalable wear resistant 3D printed slippery liquid infused porous surfaces (SLIPS)
    (Elsevier, 2021-10-02) Shams, Hamza; Basit, Kanza; Khan, Muhammad Ali; Mansoor, Asif; Saleem, Sajid
    Surface wettability is a measure of adhesion and repulsion of liquids on a material’s surface, where surface wettability may be altered by creating a new interfacial surface between the base material and the target liquid on top. Where the interface comprises of a liquid that is locked in the pores or ridges of the base material, it is then termed as liquid infused surface (LIS). LIS alters the wettability due to the distinctive properties of the interfacial liquid which now forms the new surface. If the interfacial liquid is repellent towards polar (hydrophobic) and non-polar (oleophobic) liquids, the overall surface becomes slippery (amphiphobic) and prevents any new target liquids from adhering. This phenomenon leads to the definition of slippery liquid infused porous surfaces (SLIPS), where this term not only describes its role but also its fabrication route. Here a two-step facile method is presented to quickly transform any 3D printable polymeric material into robust SLIPS, irrespective of the wettability properties of the original polymer. The complex geometrical porosity required for locking the interfacial liquid is achieved using Fused Deposition Modelling (FDM) setup. Surface wettability characteristics of the 3D printed porous structure are then enhanced by increasing the liquid-adsorption sites where the locking of the infused interfacial (repellent) liquid takes place. The SLIPS demonstrate low rolling-off (sliding) angles with both polar and non-polar solvents of up to 2 degrees with high resistance to mechanical abrasion undergoing sliding frictional wear. The robust SLIPS as produced can be quickly scaled up using existing processes used in the laboratory.
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    Vibration analysis approach to model incremental wear and associated sound in multi-contact sliding friction mechanisms
    (American Society of Mechanical Engineers, 2023-07-04) Basit, Kanza; Shams, Hamza; Khan, Muhammad Ali; Mansoor, Asif
    This paper proposes a simplistic approach toward estimating incremental wear in a multi-contact scenario using a vibrational analysis approach and in turn goes a step forward to model its associated sound. Predicted wear depth and frictional sound are compared to the experimental values obtained using a standardized pin-on-disc tribometer setup affixed with a free-field microphone to capture air-borne noise. The results show good conformity between the proposed analytical model values and the standardized experiments, hence ensuing that within certain limitations, the proposed model and the intended approach can effectively be used as a good estimator of wear and its sound in a multi-contact scenario.