Winter season started, Stressmen 16

Local mountains are covered by snow:

And the rain forest is soaking:

Last boat is heading home with the hold full of sockeye:

And my story is continued with the episode where another boat is involved. Stressmen 16

Some of summers I spent in expeditions. For example, in 1978 Kostya Cedric arranged my work as a diver for the Laboratory of Sturgeon Efficiency in the Central Institute of Sturgeon Fishery in Astrakhan.

Early morning one day in July the Yak-40 took off Kurumych runway. The Grushinsky festival field looked as a dirty patch on the green Volga’s meadows. After couple of hours we landed in Astrakhan with its cholera. We were very careful and didn’t eat in the cafes or restaurants. On the first day in the river port we took our Kazanka motorboat, bought big sac of vobla and eat only this dried fish in day time, avoiding public places and public transportation using our boat for reaching different places in this city with many water branches and canals inside. In the evening we had hot homemade food, like soup, supplemented by glass of vodka. After several days of my contract negotiations and signing it in the Central Institute of Sturgeon Fishery I got my paper for field work in the Laboratory of Surgeon Efficiency. The laboratory was analyzing efficiency of seven artificial hatcheries in Astrakhan. The goal was to define which technology of feeding is better and what age and size the baby fishes have to be when they are freed for wild life.

The “field” was on the last Volga delta island in the Caspian Sea. Initially Kostya planned to put me on the aquarium boat that cruised between hatcheries and Caspian Sea transporting baby fiches there and providing field camp with samples. Unfortunately aquarium trip was scheduled only in the end of month. Therefore Kostya using all his links in Astrakhan managed to arrange my trip aboard Academician Lomonosov boat that belonged to another research institute, Caspian Scientific Institute of Fishery. They were going to South Caspian for analysis of sprat catching efficiency.

10 a.m. of the 9th of July Kostya and I were staying on the bridge of the Academician Lomonosov vessel. The captain, head of the expedition, navigator and radioman had a morning drink there discussing last events. Kostya reacted to this very positively and proposed our bottle of vodka to their table. It was accepted and the Russian mariner’s breakfast was continued. I described the reason of my presence aboard and the place of my destination. The beacon #95 is the place where boat has to stop for my landing to the lab camp. Kostya made simple sketch of the camp area and pinned this pies of paper on the window frame. This saved me in 12 hours.

Lomonosov managed to push off only after 11 a.m. when the crew refilled their vodka stock in liquor store which was opened at 11 a.m. and not a minute earlier. The sailing by Volga-Caspian channel was blind drunk. The boat moored and several villages on the way where crew had a quick trip to local liquor store for additional vodka supply. By my fortune there were several trainee sailors whom vodka was not allowed. One of them was steersman and I explained him why I am here and where I would like to escape from this vessel.

After sun set captain was on the bridge looking at the water ahead. The beacon #84 happened to attract his attention.

“Stop engine!” – he commanded and changed engine order telegraph to STOP position – “Dinghy overboard!” – and then, addressing to me – “Slavka, I know this place!” – fingering to open water around the boat.

Knowing well how stubborn the captain is and difficulties to take off his command I decided to play by his rules:

“Steersman! Report the number of the beacon we pass!” – I demanded by very loud command voice.

“Number eighty four, Sir!” – young sailor supported my game.

“What is the number of the beacon of my destination?”

“Number ninety five, Sir!”

“Full speed!” – I commanded and steersman changed telegraph for FULL SPEED position.

Captain left the bridge and I didn’t see him again.

It was dark when we approached beacon #95. There were only two sober guys on the boat: steersman and I. And I started to act. I put telegraph into VERY SLOW and switching on loud-hailer started to outcry:

“Levin! Dingy to the boat! Levin! Dingy to the boat!”

And I used search light, beaming to the camp shack that was seen on the right.

I was so lucky that Sasha Levin, the head of the lab, was in place, jumped to the dinghy, switched motor and managed to catch the boat.

Being under overboard, looked at the deck he asked without big surprise:

“All are drunk, of course”.

“Yes, take my backpack, please” – I replied and jumped to the dinghy.

It took us close to one hour to be back to the camp.

Missile Force and Artillery Day, Stressmen 15

Strange title? Not really. The November 19th as the “Missile Force and Artillery Day” existed as a holiday in the Soviet Union since 1964. I remembered about this occasionally through my Russian blog. And I marked this event with a walk and several photos which look nostalgic like they could be made in Russia, at least the fist two of them.

The birch alley:

The slough in golden decoration:

But two other are returning to the Lulu Island.

Golden November delta in sunny day:

Great Blue Heron takes a nap on the willow:

And the piece of my story today has several nostalgic notes too. Stressmen 15

The structural research wasn’t the only thing we were doing. And I will try to show some details of the lifestyle we had in those times. Of course this is individual subject, but there are some general facts that can be interesting for the reader. The working week had 40 working hours and two days for the weekend in average. Leisure time can be filled with cinemas, theaters, exhibitions, libraries, concerts, swimming pools, gyms, restaurants, dancing clubs and bars. Even so expensive activities like downhill skiing, sailing, scuba diving, paragliding, tennis, aviating, were affordable and mainly free of charge. If you had a wish, for example, for aviating, you had to become a member of aviation club, attend all training lessons and show good test results.

Dacha is another very peculiar time spending tool. Dachas (piece of agricultural land with country house) were affordable for every family in the Soviet Union. Starting from April and till November agricultural works could take all your spare time. Camping was alternative to dacha and there were many so called “tourist bases” providing simple services for those who prefer more active even than dacha way of leisure time style.

We used all these opportunities. I was a member of two sport clubs, scuba diving and sailing, and had two vessels under my command: six rows yawl and centerboard of M class. Yawl belonged to divers club and we used it for Volga river tours. And sail club centerboard was a good mean to get some adrenalin if the wind is strong. My family had a dacha but not spend all our spare time there.

As a researcher in academic institution, I was lucky to have one and half month of vacation every year in July-August. Four weeks of this time my family and I prefer to spend on the Volga islands, just 40-50 kilometers upstream from Samara, with famous Shiryaevo and Solnechnaya just villages across the river. The Rainbow tourist base of my wife’s company provides us with spacious cottage equipped by fridge, stove and TV, small boat “Ruff” and coupons for base’s dining.

The life on the island was intensive: pleasant jogging in the morning with short swimming after morning exercises; forest walk and berries picking after breakfast; boating to the sand island in the middle of the Volga River after lunch, bathing, swimming, playing badminton till evening there; dinner and different kind of sport games till the sunset. Fishing, sailing, crawfish hunting, excursions to the villages and Ghiguly Mountains cross the river, meeting with the friend that visited us on the island have to be added to the list. Several times during these four weeks we visited our dacha to collect ripe tomato, cucumbers, apples, black currant, carrot, peas and other 100% organic fruits and veggies that were growing at our land without big attention from our side.

Mushrooms and Stressmen 14

The fall forest is beautiful:

And we have second shot of honey mushrooms:

They are very tasty as fried and marinated.

Stressmen 14 is still about my PRASAK time.

PRASAK was a real software product with appropriate user’s manual including installation package. We had sixteen clients from defense design bureaus mostly. What is interesting from today software industry problem viewpoint the first software pirating in the USSR happened in the end of seventies with our program. One of our clients, from the “Universal” factory if I remember the name correctly, used PRASAK for their air-deployed heavy equipment platforms design. The stress leader in this organization, Mr. Khitrov, was good engineer and even scientist in his soul. He had his own ideas related to finite element method realization and he was not bad in M-20 programming. As a result of such combination of knowledge, experience and analysis demands in his area he started his own modification of the PRASAK software without informing NIG-1 authority. Modification was not significant but Mr. Khitrov called it PRASAK-M and began his own marketing campaign. Fortunately the finite element analysis world was so small in those times that we knew about this unsanctioned sale intention very soon and stop it. Mr. Khitrov became NIG-1 official partner and distributor after this.

Many interesting airplanes and other flying machines were analyzed and improved with the help of PRASAK. For example, the Be-30, one of very effective regional turboprop; the M-15, agricultural jet, effective duster designed and manufactured in Poland; windows reinforcement for the Tu-154; antenna pylons for the A-50; missiles launch equipment created in Kovrov; something that they are still producing in Arazamas-16, which is known as Sarov today; modifications of the R-7; ecranoplans; the Tu-160. I wasn’t involved in all of these analyses but had a chance to watch at least some of the results.

Tupolevs didn’t have ability for wing-body blend structure analysis during their Product 70 (known as the Tu-160 today) design. And they had no even appropriate BESM-4 or M-220 computer in their possession for PRASAK installation. Therefore two Tupolevs engineers arrived to KuAI with secret mission for wing-body simulation and analysis.

One night I arrived to Building #1 where our computers were installed to continue my analysis of the Il-76 structure. The BESM-4 was still occupied by the Tupolevs team under Sergey Rychkov’s supervision. Plotter was busy with drawing something very familiar. The B-1 contours of the central airframe with wing hinge were on the paper. The Tupolevs engineers looked confused by my presence. They didn’t want somebody had a look at what are they doing here. My time started at ten, but after short discussion and Sergey’s explanations of the priority and their plan to free computer for me in couple of hours, I decided do not insist on my privilege.

It was 10 pm of the nice late August night. Windows in the computer hall situated on the first floor were opened, night city beckoned by after hot day freshness.

“Okay, I’ll be back at noon. Do not lock the window” – I told to Sergey and escaped through the window.

I had intention to walk to Volga embankment and maybe had a swim. But my plans were changed by Dima Chegodaev and Valya Sabilo whom I met soon on the Krasnoarmeiskaya Street.

“What the hell are you doing here?” – Dima asked me.

“Killing time before my night shift starts” – was my answer.

“Nice, we are on same way. Let’s go and drink vodka”.

I accepted this invitation. Dima was very interesting and popular person who had huge amount of friends. Every meeting with him was a bright event.

We went to Ghiguly restaurant. It was busy time and all tables were occupied. Doorman waited some cash from us but we didn’t pay attention to his expectations and headed inside. No way, this guy looking like ex-KGB sergeant stopped us showing to me and saying:

“I do not allow you to go inside because you have no socks!”

This was true. I really had no socks, only light summer sandals. Valya who was wearing shoes told me:

“Let’s go out and I will give you my socks”.

We went out and I showed them café Sneghinka (Snowflake) on the opposite side of the street:

“I think that this is a better place. Let’s go there”.

My proposal was supported and in a minute we were greeted by waitress in this more democratic place. Two hours were spent in warm conversation and in quarter after noon in the morning I was back at the BESM-4 room.

Quiet fall life on Lulu Island and Stressmen 13

Oval is opened and ready for the 2010:

The doors are really opened and you can come in:

Nice modern facilities inside but I prefer my outside exercises in the places like this:

Then it’s great to watch pilots landing skills together with eagles:

Or other pilot technique to navigate this huge bulker through our delta:

The story is continued with Stressmen 13

There were many other interesting problems in the Ilyushin Design Bureau in the end of seventies. One of them, analysis of the Il-102 frame, gave me a chance to look at very unusual structure. Ground attack aircraft had armor panels as fuselage structural elements. The wing had huge landing gear what left nothing except leading edge for torsion balancing. But it worked and only small modifications of the initial project were done on the base of our analysis and airplane was built. Looking ugly with its humped fuselage it was sitting in the assembling rig close to the Il-86.

Same time Volodya Peresypkin was looking for the effective wing structural scheme for the future Il-96. Solovov’s sandwich element was used for this purpose. Analysis of internal forces and theoretical material distribution gave good hint for the new scheme. Different backswept wing boxes with landing gear beam were analyzed too. All of them including Il-86, Boeing-707, Boeing-747, A-300 showed that there is undesirable interaction between landing gear beam and wing box in the area where beam is attached to the rear spar. The new scheme was found with small triangle thin-wall box behind the spar between spar and beam, which makes this interaction softer. The scheme was protected by patent and really implemented in the Il-96 wing structure.

Trips to Moscow were often. I liked Ilyushin Design Bureau and used every opportunity to walk through its experimental plant to see what new they have in production. Huge rigs for the Il-86 and small for the Il-102, the riveting, cutting, stamping, machining, assembling – I still remember sounds and smells of this walk. During lunch time we visited very nice canteen with good food that was much diverse and tastier than we had in KuAI. Moscow was announced as a “city of communist style of life” and Muscovites really lived better life than people from the provinces.

Ilyushins used not only PRASAK in that time, but Systema-4 which was TsAGI’s production, created by Vitaly Chuban’s team. It was written in FORTRAN for the BESM-6, Soviet super computer. I liked to go to BESM-6 hall to see this giant alive. But Our M-220 was situated on the B territory, 15 minutes walk from main facilities. And we liked this too as it gave us a chance for shopping and even drinking couple of beers on the way from one place to another.

There were several places for beer drinking in vicinity of Central Aerodrome area. The most popular between us was a very simple beer-bar in Petrovsky Park near Petrovsky Palace which was occupied by Air Force Academy named after Ghukovsky. Great Russian history is presented here everywhere. It was pleasant to drink the bear in the place that is surrounded by Russian aviation historical artifacts and discuss current aviation problems that really face us. Many solutions were found here during friendly conversations supported by Ghigulevsky beer and pickled herring on the piece of black bread.

Fall Urban Views and Stressmen 12

Rainy day in Vancouver is what we got used too. And I like such days and my walk in Kitsilano Beach and Granville Island in rainy weather.

The harbor is very quiet:

Downtown looks attractive from under the bridge:

Aquabus has rainbow colors what makes it cheerful:

This boat had a very high tide one day:

Granville Island is wearing fall colors:

And I continue my story, Stressmen 12

One morning at the end of November 1977 Ekaterina Alekseevna told me that I have to go to Moscow and resolve the problem of the Il-86 nose landing gear box collapse.

“Last night Abramov gave a call and informed me that during towing test they turned the nose leg inside out. Ghenya Makeev and Nina Kell will go with you. You have to create the model, simulate the test, understand well the reasons of the failure and find repair variants in two weeks” – was the order.

In the next day morning Aeroflot’s Tu-154B brought our team to Domodedovo airport. We took the bus outside the terminal and in one and half hour arrived to the Ilyushins Design Bureau check-point. Our passports and so called warrants were examined and recorded, the First Department (State Security) certificates taken out to be returned on our way back. Only after this we got our passes to enter inside the fence.

The Airframe Strength team was situated on the second floor of the old design office building. Valery Ivanovich was glad to see us:

“Let’s go and have a look at the airplane” – was his proposal after several words of greeting.

“OK, but let’s take our hotel orders on the way” – I answered, knowing well, that if we do not do this now, later they will close the service office and we will sleep on the street.

“Yes, let’s do this too. But sorry, guys, all rooms on Pilot Nesterov Street are occupied now, therefore we booked your rooms in Zarya.

“Holly smoke! Have you ever been there yourself?” – Ghenka exclaimed. We had the experience of staying in these Altay, Vostok, Zarya row of hotels that were built for 1957 World Youth Festival and well known now as a chip places that are very popular between people from Caucasus and Middle Asia Republics.

“What can I do, guys! I have no hotel and my two bedroom apartment is not good for your staying too”.

“OK, we will survive this time as did this before” – I put a period into discussion.

And the work started.

The front leg niche (thin wall box type of structure) is pressurized as it is situated in the fuselage pressurized area. The thin wall structure was stiffened by ribs, positioned inside the fuselage, leaving outside wall surfaces smooth. The stiffening of the box was designed to prevent buckling of this thin wall structure under internal fuselage pressure. Working very closely with designers, who provided us with geometrical and material data, we created finite element model during the first week. Then, through calculations, we found that ground towing load case leads to high compressions in some areas of the box structure, which never happens in flight conditions with pressurized fuselage. This compression was a reason of buckling and structural collapse. The effective repair variant was found too, what was reinforcement of the existing system of stiffeners in particular area.

Beautiful Fall and Stressmen 11

It was a nice walk in the neighborhood. What the impressive colors around! Look at this:

And at this:

The bays are covered by thin veil of mist:

And forest is really golden:

And this is continuation, Stressmen 11

My first scientific public presentation happened at TsAGI’s “Young Scientists Conference”, which Sergey Rychkov and I attended in 1978. I reported on the issues of the Il-76 wing-fuselage interface and its modification, Sergey presented problems of the Il-86 rear fuselage structure and fuselage-empennage interaction.

We arrived to Moscow week earlier with our usual tasks at Ilyushins. The conference placards were prepared in the company’s hotel room on the 7 Pilot Nesterov street at night time after our main work in design office. The conference took place in the TsAGI’s Palace of Culture in Ghukosky downtown. Electrical train was common means of transportation to this place from Moscow. You have to take it on Kazansky railway station and in one hour of pleasant trip in Moscow suburbs the Otdykh (The Rest) platform surrounded by pine forest is a place of your destination. I like the walk from railway platform to TsAGI through pine forest and quiet small town streets.

The personnel of the TsAGI’s third department were our major listeners, reviewers, referees and critics. Vladimir Fedorovich Kutyinov, the Head of this department, paid attention to the event and asked his people to take part in the conference actively. Therefore it was a chance for me to make acquaintance with Georgy Zamula, Eugeniy Lipin, Victor Biryuk and other TsAGI leads. There were many questions to the presentation, our illustrations of structural behavior were really interesting for audience. Georgy Zamula stressed importance of detailed structural analysis on the base of finite element calculations. He praised our reports and told that these are examples of structural analysis he would like to see his guys provided him.

Conference banquet was very impressive by its excellent buffet with big amount of food and drinks. But, what was really important, there were many young engineers and researchers, not all of them mails, good music and very good new acquaintance.

After successful presentation in TsAGI I had another public affair: examination on the Marxist Leninist Philosophy. We had it on Tuesday of the week after our return from Moscow. Of course I was not prepared but something told me that this test can’t be serious. The event took part in the philosophy classroom in the first building of KuAI. Docent Taller met us and we got our questions. I read them and then started to look on the walls which were covered by placards with major dogmas and communist leaders’ citations. Of course I found several of them that suited to my questions. And when docent asked if somebody is ready I raised my hand.

Robert Taller looked at my piece of paper and understood the situation clearly. But instead of asking additional questions and digging dipper into my knowledge of the subject he started conversation about my research work. I told him the fresh story of my participation in the conference and what kind of research I reported there. He was really interested and asked many questions about the Il-76 structure, the situation in the Ilyushin design bureau and my future career in structural analysis field. We spend ten minutes in this conversation when Docent Kwitnoy entered the room. Robert took my student record-book and announced:

“Excellent”

But Mr. Kwitnoy stopped him by saying:

“Wait, wait, let me have a look”.

He took my paper, had a look, understood everything and acted in a wink:

“Tell me, what else Vladimir Ilyich told about class definition except what you rewrote from the wall?”

I had no answer to this question ant to three other questions he asked me after first one.

“Very bad” – was his verdict and he tried to take my record-book from Robert’s hands. But Robert kept it and asked to step out for negotiations. They went out the room and in couple of minutes returned back. Robert announced:

“Passably” – and put mark into examination log and into my record-book.

I do not know what kind of discussion they had, but of course I was mad about Kwitnoy uprising in examination room. It was upset event but I forget about this in fifteen minutes after returning to my routines of NIG-1 research duties.

Walking in the rain and Stressmen 10

It was hot and dry summer this year. September and half of October were unusually dry and warm too. But finally rain came back and we have usual weather which still pleasant for cows in Delta:

And it still pleasant to walk in parks like this:

And of course, in the forest:

Such walks helps to remember some events, therefore I continue, Stressmen 10

The Il-76 was not the only problem that NIG-1 had in hands in those times. Sergey Rychkov analyzed the rear fuselage of the Il-86, Russian “respond” to the A-300. The first assembled airframe of the Il-86 was tested for static load cases in the Inlyshin’s huge testing facilities close to assembling shop and there were several problems with the structure. Volodya Peresypking managed engineering aspects, Katya Ivanona provided administrations. She pushed Volodya to start writing his PhD thesis. And in parallel to this very important problem of the future Il-96 wing to fuselage interface was under analysis and optimization in the NIG-1 too.

Our travels to Moscow were often. We prefer to take train as a mean of transportation. It took us 18 hour by “Ghiguly” speed train to reach Moscow. You board the train in Kuibyshev in the afternoon and next early morning step off on the platform of Kazanskaya Station in Moscow. Comfortable enough compartments gave you a chance to have good chat, informal information exchange, and even some rest and good sleeping. There was one other reason why we liked railway better than air transportation. There was shortage of the food and goods in the USSR in that time. But Moscow, as a city of communist style of life, was supplied much well than other cities and regions of the country. Therefore every trip to Moscow was the trip for shopping. For example, I had special 60 liter backpack for my Moscow travels. And every time on my way back it was filled up with such things like apples, oranges, meat, coffee, candies, cheese, bananas, sausage, bottles of vines and other similar stuff. The weight of such loaded backpack can be heavier than 40 kilograms, but Aeroflot, the only airline in the Soviet Union, allowed you to take 20 kilograms aboard and the price for extra weight was high enough.

NIG-1 as a scientific research group had to have personnel with highest level of qualification. There were two doctorate degrees in the USSR and still are two in Russia: Candidate of Science, what is equivalent to the Western PhD, and Doctor of Science, what is higher than PhD and has no equivalent in North America, but has something similar in Germany and France. Being researcher we were motivated to get doctorate degree, but this was not simple. First of all we had to attend two courses: English language and Marxist Philosophy and then, finishing them, took two examinations on these subjects. We were assigned to this course together with Sergey Rychkov. English language lessons were very interesting for me. I understood importance of English for my career. But it was obvious for me even in the middle of 70s that Marxist Philosophy was absolutely inapplicable to real life. I attended only one lesson of Professor Taller and understood well that he has same opinion.

And of course, being researches we had to take part in conferences with our own reports. Publishing of our articles was compulsory too. One of my first scientific papers was written in collaboration with Valery Mischuk and Volodya Peresypkin. It is based on the analysis of the Il-76 wing to fuselage interface.

Fall colors and Stressmen 9

I like this bog area on Lulu Island:

It’s interesting that blueberries are still here:

And they are tasty:

And I continue the story, Stressmen 9

3. PRASAK time

My first serious structural analysis task was related to the Il-76 wing-fuselage interface. The ground fatigue test revealed low life for several primary structural elements in the zone where the fuselage was attached to the wing. First of all it was the upper part of the frame #41, which is the main frame attached to the rear wing spar. There was a fast propagating crack in the frame web.

Drag angle that connected stringer #9 and rib #4 had fatigue damages too. And there were two more places with fatigue problems: fasteners that connected stringers #0 and #2 to wing ribs and panels, and insulation web between rear spar and fuselage flat pressurized panel behind the wing.

NIG-1 office was situated in the KuAI’s building #3 on Moskovskoe Shosse street but BESM-4 was placed in the building #1 in Kuibyshev downtown on Molodogvardeiskaya street. This means that we traveled often in the city. But the major peculiarity of our computer work was its scheduling for the night shifts. For several years I had approximately one night shift per week. And this was not only for me but for major personnel of the NIG-1.

Soon we got another computer with M-20 command system. It was M-222, a little bit advanced in comparison with BESM-4, with magnetic dram and wider magnetic tapes, what made it faster.

My new task demanded often travels to the Ilyushin Design Bureau. They were situated in Moscow near central airfield the former Khodynskoe Pole. Sukhoy, Yakovlev and Mikoyan are placed near by too. The Ilyushin’s “strength of the airframe” brigade headed by Valery Abramov were our clients. Finite element method was not popular in the design bureau in that time. Most of analyses were hand calculations. Certification requirements were covered by natural tests. For the Il-76 fatigue evaluation they used to stands: fuselage and wing. The fuselage stand included the major portion of the fuselage itself and short wing imitator. And wing test consisted of the wing itself and short part of the central fuselage.

Our model was much more accurate for wing-fuselage interface analysis in comparison with what analytical methods. And very soon we proved that there are stress concentration in the fatigue damaged areas. Visualization of the displacements and stresses in the area revealed the reasons of crack concentrations very soon. Our illustrations were used for repair decision making.

Russian geese back and Stressmen 8

Russian snow geese arrived:

I call them Russian because they were born in Russia on the Wrangler Island. It looks that they like Lulu Island and enjoy their staying here:

My story is continued, Stressmen 8

Sergey Rychkov graduated from KuAI one year later than I but he wasn’t enlisted for the military service and started his job at NIG-1 one year earlier. Sergey has good brains and interest to what he is doing. The interest led him to programming in M-20 machine codes, and, after some exercises, he started to realize new ideas for the PRASAK development.

The first idea was implementation of the Fully Stressed Design (FSD) algorithm. This is important tool for structural optimization at early design stages. Sergey programmed the simple recurrence relation for membrane element thicknesses and rod cross section areas. The program worked successfully and was used for so called theoretically optimal material distribution search. Some researches are still playing with similar programs calling them topological optimizer. And this was and still is practical approach. Fully stressed algorithm deletes materials from the zones where it is not loaded and adds material in places where stresses are higher than allowables. Such fully stressed design gives good hints for designer how the structural scheme can look like. And even more important for designer is the knowledge about internal forces distribution in the FSD. Internal forces are the base for real detailed design. This technique was used effectively for structural design of the fuselage main frames for blended wing-body schemes in particular.

The second idea was programming for plotter. It’s so difficult now even to imaging how we managed to debug finite element model without visualization. Yes, it was not simple. But we had no not only monitor screens, but plotters too. Therefore, to see what our model is we made visualization by hands using squared paper. All this changed when KuAI obtained the first plotter, named Vector. Vector was one pen two axis plotter with simple command system. There was only one computer, BESM-4 to which we could connect it. However there was no software even in M-20 codes for the Vector in our possession. Somebody told us that programmers in Novosibirsk University wrote this software for Vector attached to BESM-4. In January 1977 I was sent for business trip to Novosibisk Academ Gorodok (Campus of the Siberia Branch of the Russian Academy of Sciences) with the order to make copy of their software. I made two copies and brought them back. The software realizes the basic plotter command like “lift the pen”, “drop the pen”, “make horizontal incremental step”, “make vertical incremental step”. These four commands were enough for Sergey to write a program which made our work much more effective.

Six year anniversary and Stressmen 7

Six years ago we landed here:

Six years are a children age and we still continue to wonder the beauty of the Beautiful British Columbia.

Walking on the beach I was thinking about continuation of my story. Stressmen 7

The NIG-1 had a bicipital leadership in the faces of Katya Ivanova and her husband, Volodya Peresypkin. Katya was a good manager and Volodya provided engineering supervision. The first successful algorithms and programming of the finite element method was done by Volodya. PRASAK is the name of the software written in M-20 machine codes and working at such computers like BESM-4, M-220 and M-222. As usually the first version of the PRASAK had lots of bugs and Ghenya Makeev was a person who debugged it effectively, tested, made some modifications and shaped finally into commercial version, which could be distributed. The PRASAK’s finite element library contained several elements: rod, triangle, shear panel, membrane panel and I-beam. Four triangles were used for panel creation. Internal node was eliminated during triangles combining. I-beam element was a combination of web (membrane panel) and two caps (rods). In the early 70-s, knowing nothing about “shear locking”, Peresypkin and Makeev resolved problem of excessive shear stiffness by redistribution material between web triangles. Beam’s caps had eccentricities and element was very effective for simulation of the spars, ribs and frames.

There were several part-time researchers in the NIG-1. One of them, Alexander Solovov, created effective tool for the wing topological optimization in the PRASAK’s package. The tool allowed defining of the number and position of spars and ribs, their orientations and mass properties together with mass properties of the skins. Special eight node ”sandwich” element was a base of this tool. The “sandwich” consisted of two membrane skins and pure shear core between them. Such elements were used for wing structure simulation at the earliest design stages. Several critical load cases have to be applied. Structural mass was minimized and von Mises stresses in the skins and shear stresses in the core were constrained by their allowable values. Fully stressed design algorithm was applied to the model. The convergence was reached fast due to the fact that such structure behaves like statically determined. Main internal loads distribution in the skins and core were used as major output. Their analysis gave a good idea about spar positioning, their orientation, rib’s pitch and orientation. So called “theoretical weight” was defined by this model too. This is a weight of such fully stressed sandwich model. “Theoretical weight” is a good criterion for different structural schemes comparison at early design stages.