scholarly journals Preparation and thermodynamic analysis of the porous functionally graded bolted joint

2019 ◽  
Author(s):  
Wenbin Zhou
Keyword(s):  
Stress Concentration ◽  
Thermal Protection ◽  
Space Vehicle ◽  
High Strength ◽  
Functionally Graded ◽  
Bolted Joints ◽  
Service Reliability ◽  
Bolted Joint ◽  
Graded Materials ◽  
Thermodynamic Simulations

Ceramic-metal functionally graded materials (FGMs) have been extensively used in aerospace engineering where high strength and excellent heat insulation materials are desired. In this paper, the thermodynamic behavior of the Thermal Protection System (TPS) used bolted joints made up of porous ZrO2/(ZrO2+Ni) FGMs is investigated by finite-element (FE) modeling. The bolted joint is subjected to reentry heating corresponding to the Access to Space Vehicle. Thermodynamic simulations are carried out to yield the transient response of the porous ZrO2/(ZrO2+Ni) functionally graded bolted joint (FGBJ). The effects of the preload on the thermomechanical behavior and service reliability of the bolted joint are numerically analyzed in detail by ABAQUS codes. It is found that the preload relaxation of the bolted joint occurs at elevated temperature, and the preload has significant influence on service reliability of the bolted joint under transient thermomechanical circumstances. With the increase of the preload, stress concentration which occurs at the root of the first thread of the bolt increases rapidly and predominates in service reliability. Proper preload is thus defined to balance the service reliability and tightness of the bolted joint. Further studies show that the shape of the nut has a great effect on the stress concentration of the thread, the optimized nut is designed to reduce the stress concentration of the thread, and thus the reliability of the bolted joint is also improved.

scholarly journals Load distribution in threads of porous metal-ceramic functionally graded composite joints subjected to thermomechanical loading

2019 ◽  
Author(s):  
Wenbin Zhou
Keyword(s):  
Load Distribution ◽  
Thermal Protection ◽  
Space Vehicle ◽  
Porous Metal ◽  
Functionally Graded ◽  
Service Reliability ◽  
Bolted Joint ◽  
Modulus Ratio ◽  
Total Load ◽  
Metal Ceramic

Metal-ceramic functionally graded materials (FGMs) have been extensively used in aerospace engineering where high strength and excellent heat insulation materials are desired. In this paper, load distribution in threads of the Thermal Protection System used bolted joint made up of porous ZrO2/(ZrO2+Ni) FGMs is investigated by ABAQUS codes. The bolted joint is subjected to reentry heating corresponding to the Access to Space Vehicle. Effects of bolt-nut parameters including thread tooth profile, thread pitch, and modulus ratio of bolt to nut on load distribution in threads are analyzed in detail. It is found that uneven load distribution in threads occurs at elevated temperature, which mainly focuses on the first two threads closest to the nut bearing surface, with the first thread carrying 74% of the total load. Bolt-nut parameters have great effects on load distribution in threads, with trapezoidal thread, extra fine thread and greater modulus ratio of bolt to nut leading to more evenly distributed load. Further studies show that nut shape has significant effects on load distribution in threads, the optimized nut is designed to make the maximum load bearing ratio of the thread decrease to 30.21%, and thus the service reliability of the bolted joint is greatly improved.

Additive manufacturing of Inconel625-HSLA Steel functionally graded material by wire arc additive manufacturing

2021 ◽  
Vol 118 (5) ◽  
pp. 502
Author(s):  
Jiarong Zhang ◽  
Xinjie Di ◽  
Chengning Li ◽  
Xipeng Zhao ◽  
Lingzhi Ba ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Primary Dendrite ◽  
Hsla Steel ◽  
High Strength ◽  
Phase Evolution ◽  
Functionally Graded ◽  
Graded Materials ◽  
Graded Material ◽  
Wire Arc Additive Manufacturing

Functional graded materials (FGMs) have been widely applied in many engineering fields, and are very potential to be the substitutions of dissimilar metal welding joints due to their overall performance. In this work, the Inconel625-high-strength low-alloy (HSLA) Steel FGM was fabricated by wire arc additive manufacturing (WAAM). The chemical composition distribution, microstructure, phase evolution and mechanical properties of the FGM were examined. With the increasing of HSLA Steel, the chemical composition appeared graded distribution, and the primary dendrite spacing was largest in graded region with 20%HSLA Steel and then gradually decreased. And the main microstructure of the FGM transformed from columnar dendrites to equiaxed dendrites. Laves phase precipitated along dendrites boundary when the content of HSLA Steel was lower than 70% and Nb-rich carbides precipitated when the content of HSLA Steel exceeded to 70%. Microhardness and tensile strength gradually decreased with ascending content of HSLA Steel, and had a drastic improvement (159HV to 228HV and 355Mpa to 733Mpa) when proportion of HSLA Steel increased from 70% to 80%.

Conjugate heat transfer study of hypersonic flow past a cylindrical leading edge composed of functionally graded materials

2021 ◽  
pp. 095440622110481
Author(s):  
Bibin John ◽  
Sudhanva Kusuma Chandrashekhara ◽  
Vivekkumar Panneerselvam
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Functionally Graded Materials ◽  
Isotropic Material ◽  
Conjugate Heat Transfer ◽  
Thermal Protection ◽  
Leading Edge ◽  
Functionally Graded ◽  
Graded Materials ◽  
Flow And Heat Transfer

Aero-thermodynamic analysis of a cylindrical leading edge placed in a hypersonic stream is carried out using an in-house developed conjugate heat transfer (CHT) solver. Isotropic and functionally graded materials (FGM) are tested as heat shields to understand the effects of the material property on the flow structure and aerodynamic heating associated with the mutual coupling of fluid flow and heat transfer. A simplified partitioned approach is employed to couple the independently developed fluid flow and heat transfer solvers to perform conjugate heat transfer studies. This framework employs a cell-centred finite volume formulation with an edge-based algorithm. Both strong and loose coupling algorithms are implemented for the data transfer across the fluid–solid interface. A test case of hypersonic flow over a cylindrical leading edge composed of an isotropic material is considered to validate the accuracy and correctness of numerical formulation adopted in the in-house solver. The significance of solid domain materials on the conjugate heat transfer has been studied by considering both isotropic material and FGM. The loosely coupled CHT solver required 10 times less simulation time when compared with the strongly coupled CHT solver. The interface heat flux evolution over time showed a decreasing trend, whereas an increasing trend was for the interface temperature. The current study strongly recommends CHT analysis for the design of thermal protection system of space vehicles. The thermal performance of FGMs composed of various volume fractions of Zirconia and Titanium alloy (Ti6Al4V) is assessed. The temperature distributions obtained from the CHT analysis shows that FGM with a power index of unity is a good material choice for thermal protection systems.

Neutron Diffraction Studies of Residual Stresses in Functionally Graded Alumina/Zirconia Ceramics

2008 ◽  
Vol 571-572 ◽  
pp. 309-314 ◽  
Author(s):  
Petr Lukáš ◽  
Miroslav Vrána ◽  
Jef Vleugels ◽  
Guy Anné ◽  
Omer Van der Biest
Keyword(s):  
Neutron Diffraction ◽  
Residual Stresses ◽  
High Performance ◽  
Construction Material ◽  
High Hardness ◽  
High Strength ◽  
Functionally Graded ◽  
Graded Materials ◽  
Lattice Strains ◽  
Constituent Phase

Graded Al2O3/Y-ZrO2 ceramics are developed to receive a construction material combining favourable properties of both constituent components, alumina (low wear rate, high hardness) and zirconia (high strength and toughness). The high performance of this material can be reached by optimising the internal residual stress distribution resulting mainly from phase specific stresses after cooling from the sintering temperature. For this purpose, non-destructive neutron diffraction mapping of residual stresses has been employed. However, the application of the conventional method does not provide straightforward results on macroscopic residual stresses. This experimental technique uses the crystal lattice plane as a built in microscopic strain gauge and the measured quantities are then lattice strains detected in each constituent phase separately. Based on these experimental resources, the paper proposes a procedure of separation of the residual macroscopic stress from phase specific stresses. The application of the presented method is demonstrated on functionally graded materials (FGM) prepared by electrophoretic deposition (EPD).

EXPERIMENTAL STUDY ON SLIP COEFFICIENT OF HIGH STRENGTH BOLTED JOINT WITH METAL SPRAYED CONTACT SURFACE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Yusuke Nakanishi ◽  
Kunitaro Hashimoto ◽  
Yasuo Suzuki ◽  
Kunitomo Sugiura
Keyword(s):  
Steel Structures ◽  
High Strength ◽  
Treatment Method ◽  
Construction Cost ◽  
Bolted Joints ◽  
Maintenance Cost ◽  
Bolted Joint ◽  
Slip Coefficient ◽  
Surface Conditions ◽  
Contact Surfaces

There are several ways to reduce the number of bolts of frictional bolted joints from the viewpoint of the construction cost and the maintenance cost for steel structures. For example, there are the ways which are strengthening the material of bolts, or increasing the slip coefficient. This study is focused on the slip coefficient with metal thermal sprayed contact surfaces. The objective of this study is to investigate the effects of different surface conditions on the slip coefficient. Therefore, slip tests were conducted in consideration of 9 patterns of surface treatment method (3 kinds of thickness, 3 kinds of material of sprayed metal).

Self-propagating high-temperature synthesis of functionally graded materials as thermal protection systems for high-temperature applications

2003 ◽  
Vol 18 (2) ◽  
pp. 448-455 ◽  
Author(s):  
N. Bertolino ◽  
M. Monagheddu ◽  
A. Tacca ◽  
P. Giuliani ◽  
C. Zanotti ◽  
...  
Keyword(s):  
High Temperature ◽  
Functionally Graded Materials ◽  
Thermal Protection ◽  
Functionally Graded ◽  
Temperature Synthesis ◽  
Thermal Tests ◽  
Graded Materials ◽  
Thermal Barriers ◽  
High Temperature Synthesis ◽  
Spatial Composition

Self-propagating high-temperature synthesis was used to prepare boride-based functionally graded materials (FGMs) as thermal barriers for space re-entry vehicles. FGMs are characterized by inhomogeneous spatial composition, resulting in different spatial characteristics. In this work, the FGMs were composed of a ceramic [i.e., MB2 (M = Ti, Zr, Hf)] and a metallic (i.e., NiAl) side, joined together by composite layers of graded stoichiometries of the two components. Thus, in the same material, the boride end gives thermal insulation, while the intermetallic end offers an easy junction to the structure of the space aircraft. The prepared FGMs showed good adhesion between the layers and global compactness after preparation and thermal tests. The microhardness along the samples was measured, and their insulating capabilities were evaluated.

scholarly journals Paint Coating Removal by Heating for High-Strength Bolted Joints in Steel Bridge and Its Influence on Bolt Axial Force

2021 ◽  
Vol 2 (4) ◽  
pp. 728-738
Author(s):  
Tomonori Nakahara ◽  
Mikihito Hirohata ◽  
Shinsuke Kondo ◽  
Toru Furuichi
Keyword(s):  
High Strength ◽  
Bolted Joints ◽  
Maximum Temperature ◽  
Steel Bridge ◽  
Bolted Joint ◽  
Paint Coating ◽  
Axial Forces ◽  
Ceramic Heater ◽  
Coating Removal ◽  
Series Of Experiments

A series of experiments were carried out for developing a paint coating removal method for high-strength bolted joints in steel bridges. The paint-coated bolted joint specimens were heated to the target temperature of 200 °C by using a sheet-type ceramic heater. The maximum temperature of specimens could be controlled within 10% of the target value. The paint coating was easily removed by using general tools after heating. The behaviour of bolts with thermal expansion and shrinkage was monitored by strain gauges attached to the bolts during heating. It was estimated that the axial forces of the bolts were reduced by 2.6% of the initially installed axial forces, on average.

Controlling microstructure

Impact ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 46-47
Author(s):  
Takahiro Kunimine
Keyword(s):  
Mechanical Properties ◽  
Materials Science ◽  
High Hardness ◽  
High Strength ◽  
Assistant Professor ◽  
Functionally Graded ◽  
Japan Society ◽  
Graded Materials ◽  
Coarse Grains ◽  
Properties Of Materials

Most conventional materials have a microstructure comprised of minute, usually coarse, grains. One branch of materials science targets this microstructure as a means to manipulating the mechanical properties of materials to offer greater strength and hardness. Dr Takahiro Kunimine, an Assistant Professor from the Faculty of Mechanical Engineering at Kanazawa University, has recently completed a project focused on using severe plastic deformation (SPD) to develop nanostructured materials with high strength. His current project has been focusing on processing functionally graded materials with high hardness and toughness by additive manufacturing. These works, supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grant, led to the development of much stronger materials.

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