Friction stir processing (FSP)
Has been used to refine the particle structure in sheet metal and weld based on stirring friction (FSW)
Principles for the development and acquisition of patents by Cambridge TWI Co. , Ltd. in 1991 [1,6, 7].
Friction stir processing (FSP)
The tool generates heat through friction and pressure, making the material plastic without melting.
The tool then mixes the base material in a circular motion across the material horizontally (Figure 1).
2D or 3D nanoparticles can be added (Figure 2)
Change the stiffness of the material (Young's modulus).
When the rotational mixing speed is high relative to the propulsion speed, people get better material mixing.
If processed from both sides, the RHA plate can be processed to a depth of 1/4 "or 1/2.
For example, the hardness and wear resistance of the friction-stirring tib2-particle cast iron resultedin 2x ASTM G35 (Figure 3)[2, 3,8].
Since FSP is not a forming process, the pattern of the rib can be any 2D pattern (
Straight, round, spiral, etc. ).
Main focus of TheNano-
The enhanced FSP is to achieve an increase in local stiffness with minimal local material density to achieve lightweight.
The addition of nano-
In addition to the particle refinement of the local microstructure, the particles also improve mechanical properties, such as higher yield strength (YS)
Elastic modulus 
Before evaluating the effect of the FSP reinforcement, the FSP simulation method is necessary to establish the basic materials: the explosive and ballistic properties of aluminum 5182 and 7075 alloys and the equivalent weighted rolling uniform armor (RHA)steel.
Figure 4 shows the 4'x4 'blasting and ballistic plates used in the simulation.
The aluminum 5182 and 7075 plates weigh 282 kg and are 31. 8 mm thick.
The mass equivalent is 10. 9mm thick.
Two FSP reinforcement modes were selected to analyze the local stiffness of Al 5182 and 7075 basic metals.
The spacing of the FSP ribs is 4 inch and the thickness is half an inch.
Figure 5 shows that the material properties of the two FSP rib pattern simulation matrices and material properties FSP ribs selected in this study are estimated to be a change in the properties of base metal alloys (Table 1).
In this particular study, the elastic modulus of the FSP ribs increased by 100%, the YS increased by 50% relative to the substrate material, and the density increased by 10%.
Table 2 shows the matrix of the simulation studies carried out.
The baseline was Al 5182.
The mass equivalent of RHA is also simulated (equivalent RHA).
In order to study which aspect of nano-materials has the greatest influence, the elastic modulus and yield strength of nano-materials were studied respectively.
Finally, in order to gain an in-depth understanding of the ridge structure, the ribs were studied only in the Y direction, X & Y direction, and the AL 5182 substrate was completely covered.
The explosion simulation is through the use of the ministry of defense and development of Canada (DRDC), plate model.
The simulation engine is LS-
Explicit Nonlinear solver.
Figure 6 shows the simulation settings of the explosion model.
C4 is used as an explosive material, buried 2 inch (50 mm)
Deep in the soil.
As shown in the figure, the spacing between the plate and the ground is 16 inch.
Place the absolute quality of 10,620 kg on the top of the fixed frame to simulate the quality of the light armored vehicle (LAV).
Arbitrary lagoons in Euler (ALE)
This method is used to simulate the explosion.
In ALE, a background solid grid is created and fixed, and the material passes through each unit as a volume fraction.
High explosive is characterized using mat_high _ plosve_burn and eos _ jwl.
High explosion (HE)
The definition of geometry usingINITIAL_VOLUME_FRACTION_GEOMETRY.
The dimensions used in this study are 254 in diameter and 76 in diameter.
2mm height, density 1630 kg /[m. sup. 3]
The explosion speed is 6930 m/s.
Air is represented as MAT null by eos _ ideal gas.
There are many different soil models available for reference, and this study uses mat_elastic _ plstice _ water_spall (EPH)
Dry Density 1852 kg /[m. sup. 3]
Bulk modulus (K)of 50. 00 GPa.
Basic metal plates and FSP ribs are modeled with johnson-
Cook strength and failure model and Mie Glenson equation of state model (EOS). The LS-
Figure 7 shows a dynamic material card with AL 5182 strength and failure parameters.
The material properties of the FSP Rib come from the AL5182 model (Figure 8).
According to Table 1, the properties of FSP rib materials are amplified from AL5182base metal.
Due to the limited availability of strain rate effects and damage parameters of the FSP rib, it was decided to use all strain rate effects, damage parameters of the al5182.
The sound speed of FSPribs is based on the following relationship. c = [check]E/[rho]
= 6940 m/s explosion simulation results measured the peak vertical displacement of the central plate and compared with the different FSP rib modes of the explosion simulation.
Figure 9 shows a peak vertical displacement of 287mm for the AL5182.
Figure 10 shows the pressure distribution of the plate at the center and 8 inch away from the center.
Pressure waves are mainly stretched and reflected inward, especially away from the center.
For the first two milliseconds, the tensile pressure is dominant and quickly dispersed after 2 milliseconds.
This can be attributed to the decay of the explosive material after the explosion.
In general, the explosive detonation product shows a peak pressure at about 0. 5 ms (Figure11).
The pressure distribution at the center of the plate for blasting simulation is shown in Figure 10.
As can be seen from the displacement diagram, the yield strength (YS)
The impact is greatest in reducing peak displacement.
Increase the YS of AL 5182 by 50%, and reduce the peak vertical displacement of the plate from 287mm to 235mm.
The FSP rib shape in X direction only reduces the peak displacement of the plate by 8 mm to 279mm, and the FSP rib shape in x & y direction reduces the vertical displacement of the plate from 287mm to 268mm
Using FSP across the board results in a 50% increase in strength.
This means that more FSP is used to modify the plate, I. e.
The wider and denser the ribs, the better the performance due to the increase in yield strength.
At 5182 mms, the vertical displacement of the equivalent RHA plate is much higher than that of AL 318.
Although the RHA has higher strength, the thickness of the plate is much smaller in the same mass as AL 5182.
This will result in a weaker overall plate, thus showing a higher vertical displacement.
Figure 12 Figure 13 highlights the pressure distribution on the reinforcement bars inserted by the AL 5182 plate and the fsp, where the first 3 milliseconds, most of the explosion load is absorbed by the plate.
Compared to the AL 5182 and FSPinserted reinforcement pattern, the explosive pressure on the RHA plate shows a higher compression and tensile pressure, as shown in Figure 15.
This is due to the lower thickness of the equivalent RHA plate.
The internal energy of the board is shown in Figure 15.
It can be clearly seen from Fig. 15 that the higher the stiffness of the material, the lower the internal energy absorption.
Table 3 summarizes the displacement and pressure of different combinations of AL5182, FSP ribs and equivalent RHA plates.
Figure 16 captures a snapshot of the deformed board at different time steps.
The results of the explosion are summarized in Table 4.
With the addition of the FSP rib, the peak displacement and energy absorption decrease.
This is due to the higher YS of FSP Nanomaterial.
In fact, when FSP nano-
The material is mixed throughout 
The tensile and compression pressure of AL 5182 base metal is low, while the FSP rib shows high tensile pressure due to local hardening.
Next, replace the substrate from AL5182 to AL7075 with a higher yield strength.
In this analysis, the substrate was modified from a single plate 31.
8mm thick is divided into two groups of layered composite materials: 15 layers in one layer.
87 MMS messages, and 7 on the 4 th floor.
0/90 in 9375/0 and 0/90/90 modes, as shown in Figure 17.
Figure 18 shows the strength and damage properties of Johnson Cook.
Figure 19 draws the center displacement of the plate.
Plotclear showed a decrease in peak displacement from 287mm to 200mm due to a significant increase in YS of 548 Mpa compared to YS of 250 Mpa.
Ballistic simulation studies the ballistic impact performance of AL5182, AL5182 with FSP ribs and RHA plates.
The purpose of this study is to understand the ballistic properties of FSP rib pattern on base aluminum alloy I. e.
, AL5182 and al7075.
The same DRDC board from blastsimulation was cut into small coupon samples, placed vertically and tested for impact with a gentle steel plate proofing bombDTL-
1225 as shown in Figure 20.
This particular simulation device was successfully associated with another experimental test.
The item is 37mm in diameter and 100mm in length.
The initial speed of the projectile is set to 414 m/s.
The same projectiles are used in all experiments.
All the simulations and calculations are carried out in accordance with the formula of the Lagrange element, in which the nodes and materials are taken as a whole.
The pressure wave distribution on the AL5182 plate is shown in Figure 21.
Due to the penetration of the bullet, the center pressure wave is zero, and the pressure wave is more vulnerable at 37mm from the center pressure wave.
At the contact point, the shock wave travels through the plate and the projectile.
Pressure and speed when matching contact media.
One way to estimate impact conditions is to estimate impedance matching, which is derived from the continuity of pressure and velocity on the boundary between the bullet and the target plate.
In addition to the scope of this project, this includes a more detailed analysis of shock Hugoniot.
Figure 22 shows an animated snapshot of different time steps.
M & S is well positioned to capture residence on ballistic missiles, formation and blockage of the crater.
Figure 23 and Figure 24 show the pressure distribution due to bullet impact and bullet speed.
Ballistic pressure wave (Figure 25)
More obvious than in the explosion (
Figure 13 and Figure 14)
: The wavelength is 10 times shorter and there are many reflections.
It is also interesting that in both cases of FSPribs, the wave is reversed almost immediately.
This reversal is not FSP nano-
Material distribution in (
Modulus by intensity and density).
This means that the boundary between the pattern and the substrate material has a certain impact.
This is difficult to understand, however, because wave reflection is a function of material density, only 10% different.
While this effect has no direct effect on these results, it is worth noting that this is an interesting phenomenon that should be studied further.
Ballistic simulations were performed on AL7075 and FSP ribspatteron from AL7075, using 0/90 and 0/90/0/90 layered composite modes to evaluate performance.
Figure 26 shows the throwing kinetic energy, and Figure 27 shows the throwing speed.
The higher yield strength of the AL7075 compared to the al5182 did prevent the projectiles altogether.
Also note that as shown in Figure 27, the AL 7075 projectiles stop and bounce at a positive rate.
In all of these ballistic simulations, the initial velocity direction of the projectile is a negative X direction.
An animated snapshot of the deformed bomb and the AL7075 board is captured in Figure 28.
Due to the high strength of AL 7075, cracks appear on the back of the ballistic plate and prevent the projectile from penetrating, resulting in a rebound of the projectile.
The projectile slows down and transmits more kinetic energy to the target plate, expanding in diameter to form mushrooms.
As shown in the snapshot of figure 28.
The ballistic results are summarized in Table 5.
All the shells penetrated the plate.
Due to the increase in the yield strength of the insert, the FSP insert slows down the projectile and absorbs more kinetic energy.
Table 6 shows the shot kinetic energy, the pressure on the ballistic board at 37mm from the center, and the speed.
It is clear from the AL5182 and AL7075 simulations that yield strength plays a key role in preventing projectiles from penetrating the plate.
FSP ribs do have a slight benefit in reducing the level of items in x & mode.
A detailed simulation model was created to evaluate the explosive and ballistic performance of FSP enhanced AL 5182 and al7075. LS-DYNA 
The explosion and ballistic simulation responses of the AL5182, AL7075, RHA and FSP insert reinforcement bars were analyzed using a nonlinear explicit solver.
The FSP ribs exhibit effective rigidity.
Increasing yield strength is the main benefit.
Therefore, the application of nano-
Materials using the FSP process throughout the base material are better than local tearing or other stiffness enhancements.
However, the tearing does seem to lead to a phase reversal of the ballistic wave.
This aspect has not yet been well understood.
One recent benefit of FSP nano
The material reported in the literature is an increase in surface hardness .
This and phase changes should be studied to determine whether FSPNano material scans are used in armor solutions that counter kinetic threats.
This analysis assumes that FSP nanometers
Compared to Johnson, the material is of the same sex
Cooking strength and damage performance.
However, an increase in the elastic modulus and yield strength often results in plastic loss, and the assumption of the same-sex direction may not apply in reality.
In cases where the material exhibits brittle behavior, a brittle material model is required for simulation analysis, such as Johnson-
Or brittle damage model.
In addition, high representation
The strain rate properties and EOS variables of this material should be carried out.
Insert these FSPrib into the material for non-
The advantages of load-bearing parts are low density and light weight. REFERENCES [1. ]Mishra R. andMa Z.
50 pages of material science and engineering of "stirring friction welding and processing. 1-78, 2005. [2. ]Saumyadeep J. , Mishra R. S. andGrant G.
, Stirring friction casting modification for improving structural efficiency: stirring friction welding and processing a roll in the book series, Butterworth-Heinemann,2015. [3. ]Eberhardt J. J. , Arbegast B. , Stone G. , Howard S. andAllen C,"H.
Stirring friction connection and processing of advanced materials including MMCs.
"Department of Energy, 2005. [4. ]Sudhakar I. , Madhu V. , Reddy G.
Madhusudhan and rao K.
Srinivasa, "wear resistance and ballistic resistance properties of armourgrade AA7075 aluminum alloy enhanced by stirring friction processing", Defense Technology, pp. 11(1):10-17, 2015. [5. ]Komarasamy M. , Mishra R. S. , Baumann J. A. , Grant G. andHovanski Y.
"Processing, microstructure and mechanical properties of A1-related
B4C surface composites produced by friction stirring processing[6. ]Mahoney M. W.
Welding and connection ,(Jan/Febl997):p. 14-16 [7. ]Dawes C. J. and Thomas W. M.
, Welding log, 75 ,(1996):p. 41 [8. ]Charit I. , Mishra R. , and Jata K.
TMS proceedings, friction stirring welding and processing, November. 4-8, 2001, pp. 225-234. [9. ]
Livermore software technology company, Livermore CA contact information, if you have any questions, please contact Venkatesh Babu, author of Venkatesh. babu. civ@rnail. mil Dr.
Richard Gerth @ Richardj. gerth. civ@mail.
Friction mixing process
Stir friction welding RHA-
Rolled uniform armor PNNL-
National Laboratory of Pacific Northwest
Yield strength LAV-
DRDC, light armored vehicle-
EOS-National Defense R & D center, Canada
The equation of state of the US military Richard Gerth, US military taldese: 10. 4271/2017-01-