航空材料学报

2022 Vol. 42, No. 3

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2022, 42(3)

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Abstract:

Review

Research progress in airworthiness conformity verification method and technology of civil aircraft materials

JIN Haipeng, YE Lei, LIU Shiying, LI Jiarong

2022, 42(3): 1-11.

[Abstract](155) [FullText HTML] (68) [PDF 524KB](58)

Abstract:
The airworthiness development status of civil aircraft in China was taken as the starting point of review. The airworthiness alternative methods of compliance method of the materials used in civil aircraft products were sorted out, and the relevant provisions requirements of materials used in civil aircraft products such as civil aircraft, engines and helicopters in China’s civil airworthiness regulations were analysed. In the process of materials airworthiness conformity verification, the establishment of standards (specifications) based on statistical analysis is the core of material conformity verification. MOC1, MOC2, MOC4 methods are mainly used to verify airworthiness conformity of materials approved with the model. Facing the future, the application of materials with independent intellectual property rights, the construction of materials independent verification technology and capacity are the key to realize the industrialization development of advanced civil aircraft.

Research Paper

Repair of 30CrMnSiA high strength steel pull rod by laser cladding

LIU Wei, YAN Taiqi, SUN Bingbing, CHEN Bingqing, ZHANG Feng, PANG Yibin

2022, 42(3): 12-20.

[Abstract](69) [FullText HTML] (22) [PDF 6149KB](19)

Abstract:
According to the repair demand of aircraft 30CrMnSiA high-strength steel pull rod, the laser cladding process research and pull rod repair were carried out using gas atomized 30CrMnSiA powder as cladding material. The effects of different process parameters on forming quality were compared. The microstructure, mechanical properties and wear resistance of the cladding area under the optimal laser process were studied, and the damaged part of the pull rod was repaired by this process and dimensional measurement was carried out. The results show that using the optimal laser cladding process, the cladding layer with good metallurgical bonding with the base metal and dense microstructure can be obtained. The cladding layer is composed of columnar or honeycomb shaped ferrite and surrounding martensite. The microhardness of the cladding layer is about 475HV, about 36% higher than that of the base metal, and the average tensile strength of the joint is about 9% higher than that of the base metal. Compared with forged 30CrMnSiA steel, the depth of wear track of the cladding layer is reduced by 27.7%, and the width of wear track is also reduced by 35.2%, which means better wear resistance. By using this process, a repaired pull rod with good cladding quality, satisfactory dimensional accuracy and basically no thermal deformation is obtained, so the qualified products are delivered.

Effect of Cd content in Ni-Cd alloy plating on corrosion resistance of the plating

YAN Baoqiang, FEI Jingyin, ZHANG Man, WANG Jun, HAN Xizheng, ZHAO Lina

2022, 42(3): 21-27.

[Abstract](84) [FullText HTML] (29) [PDF 1482KB](30)

Abstract:
A Ni-Cd alloy plating is applied to the surface of steel component by brush plating, which can realize the double protection of sacrificial anode by cathodic protection and mechanical protection. The effect of concentration of Cd²⁺ in plating solution on the corrosion resistance of the plating was studied by using the control variable method. The corrosion potential, polarization resistance and corrosion resistance of the coating with different concentrations of Cd²⁺ were measured by polarization curve, AC impedance spectroscopy, full immersion corrosion test and salt solution immersion test. The results show that the co-deposition of Ni-Cd alloy with Cd of mass fraction of 15%-90% can be realized when the mole fraction of Cd²⁺ changes from 0.5%-5%, which belongs to abnormal co-deposition. When the molar fraction of Cd²⁺ is 4 %, that is, the mass fraction of Cd²⁺ in the coating is 69.40 %, and the corrosion resistance of the alloy brush coating is the best.

Effect of pre-deformation on mechanical property and anti-corrosion resistance of spray deposited Al-Cu-Li alloy

DU Changbing, XIAO Kai, GUAN Ruichun, PENG Jing, TANG Qidong, XU Jinjun

2022, 42(3): 28-37.

[Abstract](106) [FullText HTML] (32) [PDF 2891KB](32)

Abstract:
The effects of pre-rolling and pre-stretching deformation on microstructure, mechanical properties and corrosion behavior of Al-Cu-Li alloy in subsequent peak-aging were investigated by means of microstructure observation with mechanical and intergranular properties tests. The test results show that the pre-deformation treatment before aging promotes the precipitation of a large number of uniform and fine T₁ phase with dispersed distribution in the alloy grain, and reduces the number of precipitates on the grain boundary, so as to improve the comprehensive mechanical properties of the alloy. In addition, this precipitate microstructure can balance the potential difference between the grain boundary and the grain interior, reduce the intergranular corrosion sensitivity of the alloy, reduce the corrosion rate and enhance the intergranular corrosion resistance of the alloy.

Nonlinear mechanical behavior of graded porous material beam subjected to moisture-heat-mechanics loads

LI Qinglu, WANG Siyao, ZHANG Jinghua

2022, 42(3): 38-44.

[Abstract](75) [FullText HTML] (41) [PDF 1226KB](17)

Abstract:
The nonlinear mechanical behavior of graded porous material beams under the uniform distributed follower load “ that the load direction was changed with the deformation of structure ” was studied. Considering two kinds of porosity models with symmetrical and asymmetric distribution in gradient porous material beams, it was assumed that the material properties change continuously in thickness, and the one-dimensional temperature field and humidity field only relate to the thickness direction and change linearly. First, the two-point boundary value problem consisting of the governing differential equation and the boundary condition was converted to the initial value problem. The non-linear mechanical behavior of a porous gradient material simply supported beam made of open metal foam material was analyzed by using the shooting method. The equilibrium path and the equilibrium configuration of the two kinds of porous material beams under random load were given under different heterogeneous heating and non-uniform humidity. The influences of porosity coefficient, temperature rise and humidity on the post buckling or bending behavior of beams were discussed. The results show that there are three equilibrium configurations of symmetric porous beams under the same follower load in hot and humid environment. When $ {e_0} > 0.48 $, the bending configuration increases monotonically with the load.

Design, fabrication and properties of sandwich composites with metamaterial absorbers integrated

RUAN Xinyi, YANG Jiahua, QIU Yiping, YAO Lan

2022, 42(3): 45-54.

[Abstract](143) [FullText HTML] (45) [PDF 2985KB](44)

Abstract:
In order to achieve a kind of composite material with both wave absorbing property and certain mechanical load bearing function, the metamaterial absorbers and sandwich composite were combined. By simulation, the metamaterial absorbers satisfying dual-band and broadband electromagnetic wave absorption were designed, and the wave absorbing performances were characterized. The aforementioned metamaterial absorbers were then integrated into the sandwich composite, in which the glass fiber/epoxy composite was used as the top layer, the PMI foam was used as the core layer, and the carbon fiber/epoxy composite was used as the bottom layer. The measured electromagnetic wave absorbing performance of the final sandwich composites shows that the dual-band composite has the absorptivity of 94.13% and 99.99% at the frequency of 8.65 GHz and 10.30 GHz respectively, while the broadband composite has the absorptivity of 90.02%-99.91% at 8.25-11.61 GHz frequency range. The bending test results exhibit that the dual-band composite has the bending strength and modulus of 68.81 MPa and 7.72 GPa, and the broadband composite has the bending strength of 145.76 MPa and modulus of 9.13 GPa. The SEM photos of after-fracture cross sections show that a small area of delamination can be observed and the overall laminates bonding performance is good.

Preparation and characterization of matrix-graded polyimide composite along thickness direction

NI Hongjiang, LI Jun, XING Yu, ZHANG Daijun, CHEN Xiangbao

2022, 42(3): 55-62.

[Abstract](68) [FullText HTML] (14) [PDF 2012KB](16)

Abstract:
A resin-transfer-molding (RTM) polyimide resin, RTM-PI, was developed, and the matrix-graded polyimide composite along thickness directions was fabricated with RTM processing. The matrix-graded composite was composed of surface layers with polyimide matrix having high thermal stability, and core layers with RTM-PI matrix. The RTM processing parameters were established based on thermogravimetry, rheology and curing data of PI resins. The results show that RTM-PI resin exhibits the properties of low viscosity, super long processable time, and high thermal resistance. The lowest viscosity is below 0.1 Pa·s, processable time is longer than 300 min, and glass-transition-temperature reaches 445 ℃. The internal quality of the matrix-graded polyimide composite along thickness direction is excellent, and the reduction of mass loss after the thermal ageing at 350 ℃ for 100 h is more than 48% lower than that of the pure RTM-PI composite.

Properties of rosin based epoxy resin carbon fiber reinforced composites cured at medium temperature

LIU Yanfeng, LIU Qingman, CHEN Xu

2022, 42(3): 63-69.

[Abstract](86) [FullText HTML] (31) [PDF 688KB](16)

Abstract:
Biomass maleopimaric anhydride (MPA) was used as curing agent and petroleum based E-54, AG-80 and 014U mixture was used as epoxy resin to study the thermal and mechanical properties of rosin based epoxy resin matrix and its composites, in order to further evaluate the possibility of its application in advanced resin matrix composites for main load-bearing structures of aircraft and to broaden the application field of biomass epoxy resin. The results show that the cured epoxy resin has high mechanical properties and thermogravimetric temperature. The glass transition temperature of formula F2 resin is 156 ℃, the tensile strength is 82.6 MPa, the tensile modulus is 3.05 GPa, the elongation at break is 4.2%, 5% thermal decomposition temperature is about 370 ℃. The dry glass transition temperature of composite laminates prepared from F2/U3160 prepreg is 158 ℃ and the wet glass transition temperature is 123 ℃. The dry mechanical properties are equivalent to those of 3261/HT3 composites which have been applied to helicopter rotor system, and have a high retention rate of wet mechanical properties.

Prediction method for curing deformation of conical C-shaped shell of fiber reinforced composite

TAO Yumei, ZHENG Zijun, SHAO Jiaru

2022, 42(3): 70-79.

[Abstract](83) [FullText HTML] (46) [PDF 1157KB](23)

Abstract:
The shape of fiber-reinforced composite work-piece cured in autoclave usually deviates from the original design after demoulding, which influences the product quality. In order to study the cure deformation law of curved parts, the geometry of conical C-shaped shell was described by only five parameters: generatrix length, radius at half height, center angle, half apex angle and shell thickness. Based on the virtual work principle and small deformation hypothesis, the analytic solution of the cure deformation caused by the temperature drop in the curing process was deduced. It is revealed that after curing, the thickness, half-height radius, generatrix length and apex angle decrease, while the center angle of the arc increases. Compared with the finite element simulation orthogonal test, which validates the analytical solution. A simplified scheme of finite element curing simulation by use of the path-dependent constitutive law is given. This simplified finite element deformation prediction method can cut the computing time by 80% and the implementation is much easier. By using this formula, thermoelastic finite element model and path-dependent finite element model, the curing deformation of the nose cover of a small fixed-wing aircraft is calculated, and the predicted average reduction of half-span length is 8.1 mm,7.6 mm and 6.1 mm respectively, which are basically consistent with the measured value of 7.7 mm. The assembly deformation characteristics of the part can also be explained based on the proposed analysis.

Residual compression mechanical properties after low-speed impact for laminated stitched carbon fiber reinforced aluminum matrix composite

GU Shu, CAI Changchun, YU Huan, XU Zhifeng, WANG Zhenjun

2022, 42(3): 80-88.

[Abstract](133) [FullText HTML] (49) [PDF 3904KB](30)

Abstract:
Using aluminum alloy ZL301 as matrix and carbon fiber laminated suture fabric as reinforcement, carbon fiber reinforced aluminum matrix (C_f/Al) composites with laminated stitch were prepared by vacuum pressure infiltration process. Through the drop hammer impact test at room temperature, the behavior of impact load and energy change with time was studied. The impact damage morphology was observed by optical microscope and industrial digital X-ray imaging system, and the impact damage mechanism was analyzed. Through the post impact compression (CAI) experiment, the residual strength of the composite along the warp direction under different impact energies was studied, the macro and micro fracture morphologies of the compressed sample were observed, and the compression failure mechanism was analyzed. The results show that the laminated stitched C_f/Al composites have significant local damage under impact load, with obvious pits appeared in the front damage area, and obvious meridional cracks appeared on the back. The crack length increases with the increase of impact energy. The main damage modes are matrix cracking and fiber fracture pulling out. The meridional compressive strength after impact decreases with the increase of impact energy. The compressed composites have transverse cracks extending from the end of the impact crack along the weft direction to the edge of the sample. The severity of yarn structure damage in the macro fracture of compression increases with the increase of impact energy, The micro fractures after compression show uneven morphology after fiber shear fracture.

Enhancing interlaminar fracture toughness of carbon fiber/epoxy resin composite with graphene oxide coated hydroxy iron oxide under magnetic field-style="padding-top:17.4pt"

CHEN Guan, MA Chuanguo, FU Zehao, WANG Jing, WANG Yazhen

2022, 42(3): 89-96.

[Abstract](120) [FullText HTML] (53) [PDF 2474KB](38)

Abstract:
To effectively improve the interlaminar toughness of carbon fiber/epoxy resin (CF/EP) composite laminates, toughening nanoparticles (GO@FeOOH) were prepared by electrostatic self-assembly technology, which was the needle-like hydroxy iron oxide coated with graphene oxide. Dispersed in EP matrix and induced by magnetic field, the toughening effect of GO@FeOOH nanoparticles was significantly improved. The modeⅠinterlaminar toughness (G_IC) of GO@FeOOH/CF/EP laminates was examined by double cantilever beam test. The effects of GO@FeOOH and magnetic field induction on G_IC were investigated. The results show that the GO@FeOOH can significantly enhance the interlaminar properties of CF/EP composite even at a low content of 0.5%(mass fraction), and the initial crack G_IC (0.53 kJ·m^-2) and crack propagation G_IC (0.71 kJ·m^-2) of GO@FeOOH/CF/EP are 34.2% and 44.9% higher than those of CF/EP, respectively. On the other hand, the magnetic field induced GO@FeOOH orientation along the magnetic field direction, further significantly improved the toughening effect, the initial crack G_IC and crack propagation G_IC increased 112.6% and 93.9% compared with CF/EP, respectively. The interlaminar toughening mechanism of the composite mainly includes the pull-out and debonding of the nanoparticles and the local plastic deformation of the matrix, and the pull-out of particles becomes the dominant toughening mechanism after the induction of magnetic field.

Acoustic emission characteristics of ϕ480 mm composite shell with structure and heat protection integration during water pressure test

HUI Xuemei, ZHANG Gang, HOU Xiao, CUI Hong, ZHANG Chengshuang, BAO Yanling

2022, 42(3): 97-103.

[Abstract](129) [FullText HTML] (33) [PDF 1238KB](24)

Abstract:
In order to meet the high requirements of future high-speed and high acceleration tactical missiles for shell bearing capacity and heat protection function, the integrated structure-heat protection ϕ480 mm composite shell was prepared by dry winding process, in which the structure layer adopted T700 carbon fiber/cyanate ester composite, and the heat protection layer adopted composite heat protection structure. The internal pressure, acoustic emission and hydraulic burst tests had been done for integrated structure-heat protection ϕ480 mm shell. The strain variation law, the damage type and damage location of ϕ480 mm composite shell were researched. The structural integrity of external heat protection materials was evaluated. The capacity of bearing internal pressure load was also assessed for the integrated structure-heat protection ϕ480 mm composite shell. The results show that the strain of ϕ480 mm composite shell is linear with the pressure and increased with the raising pressure. The acoustic emission signals, such as resin cracking, monofilament fracture, fiber bundle fracture and delamination are distributed in the dome areas under the internal pressure. The Felicity ratio of ϕ480 mm composite shell is 0.96 after secondary loading. The bursting pressure of ϕ480 mm composite shell is 18.6 MPa, and the vessel characteristic coefficient reaches 42.1 km. The fiber fracture occurs in the dome areas. A small amount of fiber fuzzing, broken wire and whitening appear on the surface of the heat resistant layer material, and no delamination and shedding occur, maintaining good structural integrity.

Simulation analysis of structural strength of 12 -strand two-dimensional braided PBO rope

WANG Zhe, ZHAO Haitao, LIU Yang, CHEN Ji’an

2022, 42(3): 104-112.

[Abstract](102) [FullText HTML] (38) [PDF 2978KB](16)

Abstract:
Two-dimensional braided rope is widely used in engineering, aerospace and many other fields, among which 12-strand two-dimensional PBO braided rope has excellent properties. Taking the 12-strand two-dimensional braided PBO rope as the research object, assuming that the cross section of the fiber bundle was circular, the braiding law and mechanical properties of the rope were studied. Using the circular braiding method for reference, the rope models with different knot diameter ratios were obtained. The representative volume elements of the rope model were intercepted and the periodic boundary conditions were applied for finite element simulation. The rope tensile experiments with different knot diameter ratios were carried out to explore the influence of knot diameter ratio on the rope strength. The simulation results were compared with the experimental results. The results show that with the increase of knot diameter ratio, the maximum tensile force that the rope increases significantly at first and then basically remains unchanged. An appropriate knot diameter ratio can effectively give play to the tensile performance of 12-strand two-dimensional braided rope, it promotes the study of mechanical properties of two-dimensional braided rope.