scholarly journals Experimental Study of Drilling Temperature, Geometrical Errors and Thermal Expansion of Drill on Hole Accuracy When Drilling CFRP/Ti Alloy Stacks

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3232 ◽  
Author(s):  
Vitalii Kolesnyk ◽  
Jozef Peterka ◽  
Marcel Kuruc ◽  
Vladimír Šimna ◽  
Jana Moravčíková ◽  
...  
Keyword(s):  
Experimental Study ◽  
Thermal Expansion ◽  
Time Delay ◽  
Ti Alloy ◽  
Element Analysis ◽  
Machine Method ◽  
Drilling Temperature ◽  
Measuring Machine ◽  
The Impact ◽  
Delay Factor

The drilling of holes in CFRP/Ti (Carbon Fiber-Reinforced Plastic/Titanium alloy) alloy stacks is one of the frequently used mechanical operations during the manufacturing of fastening assemblies in temporary civil aircraft. A combination of inhomogeneous behavior and poor machinability of CFRP/Ti alloy stacks in one short drilling brought challenges to the manufacturing community. The impact of the drilling temperature and time delay factor under various cutting conditions on hole accuracy when machining CFRP/Ti alloy stacks is poorly studied. In this paper, the drilling temperature, the phenomenon of thermal expansion of the drill tool, and hole accuracy are investigated. An experimental study was carried out using thermocouples, the coordinate measuring machine method, and finite element analysis. The results showed that the time delay factor varied from 5 (s) to 120 (s), influences the thermal-dependent properties of CFRP, and leads to an increase in hole roundness. Additionally, the thermal expansion of the drill significantly contributes to the deviation of the hole diameter in Ti alloy.

Experimental Study on the Mitigation Effect of Polyurethane Foam Densities on the Cylindrical Objects Entering Water at High Velocity

2019 ◽  
Vol 950 ◽  
pp. 103-109
Author(s):  
Hai Tao Qian ◽  
Shun Shan Feng ◽  
Zhi Yu Shao ◽  
Si Yu Wu
Keyword(s):  
Finite Element Analysis ◽  
Experimental Study ◽  
Polyurethane Foam ◽  
Water Entry ◽  
Analysis Software ◽  
Element Analysis ◽  
Impact Experiment ◽  
Simulation Results ◽  
The Impact ◽  
Foam Plastics

Polyurethane foam has the properties of energy absorption and mitigating the impact, it has been used in internal protection head cap of cylindrical objects as cushion material, its theory and simulation has been widely discussed by the domestic and foreign scholars, but little experimental research is involved. In this paper, a dynamic loading water-entry impact experiment was designed for polyurethane foam plastics with different densities. In addition, ANSYS/LS-DYNA finite element analysis software was used to simulate water-entry process of cushion materials with different densities. The experimental and simulation results show that the 0.18 g/cm3 polyurethane material can effectively protect the cylindrical head, reduce the stress and have a good cushion effect on it.

Methods of Describing Plastic Gear Geometry After a Temperature Change With Application to the Prediction of Gear Load Distribution

2011 ◽  
Author(s):  
Sumanth Kashyap ◽  
Donald R. Houser ◽  
Zan Smith ◽  
Senthilvelan Selvaraj ◽  
James M. Casella ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Load Distribution ◽  
Gear Tooth ◽  
Linear Thermal Expansion ◽  
Transmission Error ◽  
Distribution Analysis ◽  
Element Analysis ◽  
Slope Change ◽  
Measuring Machine ◽  
Plastic Gears

In Polymer gears, the rise in temperature not only influences gear rigidity but also tooth geometry. This paper presents methods to represent the influence of temperature by change in micro-geometry and macro-geometry parameters of the gear tooth. These macro and micro-geometry parameters of gear are entered into advanced gear analysis programs such as those for performing load distribution analysis and transmission error prediction. This theoretical model assumes linear thermal expansion of the material of the gear. This model is verified using a Finite Element Analysis (FEA) of the gear tooth. Two approaches were successfully used to model the thermal expansion of the material, one being to change the module of the gear and the other being to apply a pressure angle slope change to the tooth form. The profile change was verified by elevating the temperature of plastic gears of several materials and then measuring them on a Gear–Co-ordinate Measuring Machine. The two approaches were used in compatible load analysis programs that produced essentially identical transmission error predictions.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact
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