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Ultrasound technology has widely used in military

2017/6/3      view:
Two-way laser welding corrugated beam structure.
In our country now on active service and in the research of aircraft proposed extending its using life spans of an actual emergency needs.The use of aircraft structural life spans not only with the details of the plan, the body material and soar load related, more parts manufacturing quality and its chosen with the ultrasonic technology are inseparable.These techniques include connection technology, equipment, technology and strengthening technology, etc.
Body structure become pass by various methods of coupling force bearing as a whole, and "force" in the tens of thousands of distributed in the connection point on the structural unit (fasteners, plastic nail holes, solder joints, weld, contact, etc.) between the transfer process, continue to structure the body of repeated effect cause of fatigue damage, which in turn affect the use of aircraft structure life spans., the connection point of manufacture and equipment quality through the passing of "force" and affect the structure of the influence of the attack using become old, yea, through a variety of technology path to improve the technology of the connecting point (surface quality, collaboration, properties, structure, methods, etc.) can advance the use of the body structure taking comprehensively.According to statistics, 75% ~ 80% of the fatigue damage and damage attacks in the connection part of the body structure, it serves to show the primacy of aircraft structure fatigue life.
Full connection structure is one of the primary determinant of full body structure, guarantee the secure connection structure, used in plane reservation period not attack function to reduce or failure, is the first purpose of long life spans connection technology used for discussion.Foreign active beat the airframe in this kind of technology used are do connection technology, electromagnetic riveting technology, a variety of reinforcement technology, a variety of welding technology.All of these technologies in different parts of the structure is reasonable use ensures it has longer life spans.
Composite materials do connection technology
A new generation of airframe large scale using composite material structures has become a inevitable trend, the composite/metal composite sandwich structure connection for discussion and analysis in structural plan of the first notice.Meddle connection technology combination of bushing and the bolt/metal composite sandwich structure of the composites of the connecting pin holes to trace kneading, improve nail hole surface condition, to advance the fatigue life of metal nail hole or to improve the effect of load distribution is obvious.
In meddle connection technology, is difficult to do volume, the choice of relevant technical personnel to save capital, to do the amount of mixed and disorderly doubt simplified, chose the limited data combination, open the corresponding experimental research work, the following results:
1) do join along/metal composite sandwich composite connection of fatigue life spans, ahead of the ups and downs are more than 1 times.
2) do join can make the pin load distribution is relatively uniform, along with the close degree of collaboration with hole to add, in the first row of studs load gradually decreases, and the second row nail load gradually add, biggest nail by the first row is transferred to the second row.
3) amount of meddle too much exacerbate nail load distribution inhomogeneity, nail load difference near the XX %, even higher than the gap.
4) form the composite shaft; its flowerlike type fastener nondestructive equipment start technical disciplines and view the assessment method.
5) to small specification (Ф Ф 4 ~ 6) do independent small batch production, bushing, bolt bushing of the percent of pass can go beyond 85%.

6) for small specification (Ф Ф 4 ~ 6) do join the domestic technical maturity has arrived in grade 6, can be used in the research and development of type inspection.

Fastening hole table kneading reinforcement technology
Fastening hole table kneading strengthening technology is depend on the contact force sheet metal sandwich nail hole kneading, the elastic zone and the plastic zone around attacks, the elastic zone effect of the plastic zone compressive stress condition, hole wall attacks on metal nail hole of the fatigue life of a long life to strengthen technology.Fastening hole structure connection area table to improve the resume the spindle, mandrel rolling kneading technology were conducted, rely on slotted liner contact mandrel, avoid attacks of hole wall contact harm slotted liner kneading strengthening technology will have broad prospects.
Domestic research and development of contact type and related preparatory programme in recent years, for aluminum alloy, titanium alloy and its mix of sandwich structure system of hole and kneading strengthening technology for discussion and analysis, the corresponding experiment first assignments and conclusions are as follows:
1) single titanium alloy material (domestic) sandwich structure experiment chooses X % kneading, stature has not grown weary, and drop of XX % above, this means that X % kneading quantity influence the fatigue life of titanium alloy interlayer structure is negative.More than X % of kneading good for forward single titanium alloy laminated structure fatigue life, gain the highest near the XXX %.
2) single aluminum alloy (domestic) choose X % kneading for sandwich structure test of aluminium alloy fatigue life gain is small, the weary stature gain is not obvious, can be neglected.When arrived in 7.0.x.x % amounts of kneading, fatigue life significantly add, close to the XXX %, when kneading volume continue to increase until X %, fatigue life spans will be lower again, decline about XX %.
3) for the distribution of titanium/aluminum composite sandwich structure (see many this combination plane) three screw joint specimens, needs to plan as a whole system of two materials summarized consider hole parameters.Choose 7.0.x.x % kneading amount is a reasonable choice, but as a whole of the single titanium, aluminium alloy fatigue life spans, the influence of but increase fatigue life is limited, most add XX %.
4) in the internship plane structure with single aluminum or titanium alloy sandwich structure, also often distribution of titanium/aluminum composite sandwich structure, choice of reinforcement amount of kneading, should not only consider the above experimental research result, also want to consider internships nail uneven load causing fatigue load amplitude difference structure taking a greater impact.
Laser welding technology
Laser welding with high power density laser irradiation on the material surface, through the surface of a material to absorb light energy and converted into heat energy to weld temperature melt into a liquid, in the process of the subsequent cooling condensing end connection of two materials.It is a kind of high speed, high efficiency, high precision of high energy beam welding method, welding joint quality with electron beam welding than, but without vacuum environment, do not attack of x-rays, particularly suited to the new high temperature resistant welding combination of aeronautical structure materials.
Domestic 2006 to 2.5 mm thick 1420 al-li alloy plates for YAG laser welding, the technology of YAG laser welding parameters and weld forming and welding joint of stretching function was tested for discussion.
Dual beam laser welding means using two laser beams in the process of welding, the beam configuration method, interval, two beams of light into the light beam Angle, collections, bearing as well as the two beams of light energy than is related to set parameters of dual beam laser welding.In general, in the welding process, double beam configuration method, generally there are two, one is along the direction of welding in tandem arrangement, this method can reduce the configuration of molten pool cooling rate, reduce the weld tendency of hardenability and porosity of attacks.Another is in on both sides of weld configuration or side by side with configuration, before into the adaptability to weld gap.
Affect the primary technical parameters of laser welding are: type and the laser power, spot diameter and welding speed, laser incidence, electrode shape and standards, characteristics of shielding gas, etc,.Now, the domestic laser welding of titanium alloy sheet maturity level has greatly forward, dual beam laser welding of titanium alloy sheet structure maturity level have greater progress.
Active flux argon arc welding technology
Active flux argon arc welding technology is made by welding parts coating method of active material and the deflation of welding arc, improve the activities of the molten pool, to reduce the heat affected zone and weld quality.
Active flux argon arc welding technology in China in "fifteen", during the period of "11th five-year plan", over many engineering using the discussion homework, has achieved obvious technical progress.The use of titanium alloy corrugated web beam structure has obvious representative, for the welds scales, mechanical grinding grain, manual and so on can influence the value of fatigue life of the weld joint experiment for deepening engineering detail question for discussion.

The connecting weld surface ultrasonic shock processing technology
Ultrasonic surface strengthening is using ultrasonic wave energy, impact surface of metal parts, the parts surface compressive stress layer, to improve the surface of the parts.Ultrasonic shock processing technology in China is now in use during the seminar, during the period of "11th five-year plan" to use the technology of titanium alloy weld reinforcement processing and test analysis, welding after ultrasonic impact treatment (UIT) can effectively change the stress distribution on the surface of the weld, the tensile stress to compressive stress, the mean to - XXXMPa above.On this basis, the plan for tooling flux activity of laser welding and argon arc welding of corrugated web beam structure of weld reinforcement, has obtained certain effect and engineering experience.
Super molding/mar
Titanium alloy laminated technology
Titanium alloy laminated molding/mar connection technology is to choose super molding/mar connection technology, in the form of the structure of the multilayer of titanium alloy sheet a dysfunctional connection point between faying surface, structure fatigue resistance ability.Domestic titanium alloy SPF/DB technology while in plan and Numbers and abroad have a certain interval, but in the frame, large flap, fairing, etc bearing components have been installed on them, and opened the stacking structure of titanium alloy DB test for discussion.By titanium alloy laminated structure crack broaden the function comparison test found that the surface crack broaden the function of laminated structure, through crack expand functions and the opening Angle of tensile crack expand functions have obvious advantages, as a kind of slow crack broaden the structure, can be applied to the main bearing member on the durability of the structure, it is using the prospect of a structure method.
Laser forming and connection technology
Laser forming and connection technology is made fine powder, titanium alloy after laser melting made independent structural unit, after each structural unit processing, then join into plan appealed to the whole thing.
Domestic open the laser direct metal forming technology research units now first with Beijing university of aeronautics and astronautics, Beijing nonferrous metal research institute, northwest industry university and tsinghua university and other units.
In addition to A - 100 steel structure manufacturing domestic laser forming are also makes an exploratory research.