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Kırık çizgili amortisörler ile sürekli amortisörlerin taşıt titreşimlerindeki etkilerinin karşılaştırılması

Başlık çevirisi mevcut değil.

  1. Tez No: 66512
  2. Yazar: AHMET SALİH KAYHAN
  3. Danışmanlar: PROF. DR. ALİ IŞIK ERZİ
  4. Tez Türü: Yüksek Lisans
  5. Konular: Makine Mühendisliği, Mechanical Engineering
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 1997
  8. Dil: Türkçe
  9. Üniversite: İstanbul Teknik Üniversitesi
  10. Enstitü: Fen Bilimleri Enstitüsü
  11. Ana Bilim Dalı: Makine Mühendisliği Ana Bilim Dalı
  12. Bilim Dalı: Otomotiv Bilim Dalı
  13. Sayfa Sayısı: 68

Özet

ÖZET Bu çalışmada, taşıt titreşim modellerinin irdelenip, üç kütleli bir taşıt modeline ait hareket denklemleri çıkartılarak incelemeler yapılmıştır. Bu incelemeler sayın Prof. Dr. AIşık ERZİ tarafından hazırlanan TEST F ve VÎBRAT programlan yardımıyla yolun dijital olarak bilgisayar ortamında yaratılarak ve bu yaratılan yolda taşran simülasyonu hesaplanıp sonuçlara FFT uygulanmış sürekli ve kıtık çizgili amortisörlerin farkları ortaya konmuştur. Bu amaçla önce yol düzgünsüzlüğü ve yolun yaratılmasıyla ilgili aritmetik ortalama değer, karesel ortalama değer, standart sapma, güç yoğunluğu spektrumu deyimleri tanımlanmıştır. Burada yol düzgünsüzlüğü raslantısal bir fonksiyondur ve yoldan gelen uyanlar tekerleğe dik olarak gelmektedir. Non - lineer modeller için yol düzgünsüzlüğünün yaratılması, güç yoğunluğu spektrumunun frekans aralığında dilimlere bölünüp, integrasyonu alınarak güç yoğunluğu olarak verilmiş olan yol düzgünsüzlüğü sonlu sayıda harmonik fonksiyonun toplamı şekline getirilir. İntegrasyon aralığının bölümü eşit dilimler olacak şekilde alınarak yol yaratılmış ve yaratılan yol düzgünsüzlüğüne FFT ile güç yoğunluğu analizi uygulanarak güç yoğunluğu spektrum eğrisi bulunmuştur. Yaratılan yolda üç kütleli bir taşıt modelinin simülasyonu hesaplanarak sonuçlara FFT uygulanmış sürekli ve kırık çizgili amortisörde farkları ortaya konmuştur. Buna göre ilke olarak uyan cevabı kırık çizgili amortisörde gövde ve aks frekansında güç yoğunluğu spektrum değerinin daha yüksek olduğudur. Bununla beraber hızın etkisi, hız arttıkça her iki amortisörde de standart sapma değerlerinin de artmasıdır. Bütün hız aralığında kırık çizgili amortisörle hesaplanan standart sapmaların, sürekli amortisörle hesaplanan standart sapmalara oram sabit kalmaktadır. Bunun dışında bütün hız aralığında kırık çizgili amortisörün kırklığının etkisi kendini en çok dinamik tekerlek basıncında en az gövde ivmesinde hissettirmektedir. Boyutsuz sönüm katsayısının etkisi hesaplanan standart sapma değerlerine göre, genel olarak boyutsuz sönüm katsayısı arttıkça standart sapma değerleri azalmaktadır. Ancak iskemle ivmesi, gövde ivmesi ve dinamik tekerlek basmanda büyük değerdeki boyutsuz sönüm katsayılarının etkileri, küçük değerdeki boyutsuz sönüm katsayılarına göre daha fazladır. Bununla beraber boyutsuz sönüm katsayısının etkisinin en az hissedildiği kısmı taşıtın iskemle bölümü, en çok hissedilen kısmı da dinamik tekerlek basıncında olmaktadır. Kırıklık oranın 1 olmasıda amortisör süreklidir ve uyan cevabında standart sapma değeri enazdır. Buda amortisörün kırık çizgili özelliğinde sürekli özelliğine yaklaşması amortisörü iyi yönde etkiliyecektir. XI

Özet (Çeviri)

SUMMARY This thesis that is named as the comparison of the effects of continuos and fractured lined shock absorbers on vehicle vibrations, constitutes from six sections. Sections have been searched in the order of introduction, vehicle vibration models, model's movement equations, creation of the way, searching of the fractured lined shock absorbers in warning by a single harmonic, and stocastically warning by using continuos and fractured-lined shock-absorbers in vehicle model that is three blocked. In the first section; the defining of the problem has been made. In the second section; vehicle vibration models have been presented. In reality; vehicle vibration model is quite complex. The solution of this complex model is very difficult. In order to avoid from this difficulty models with smaller independence degree have been presented. In the third section; the movement equations of three blocked system have been found by sorting from single blocked vehicle model. The solution of these movement equations constituted is the solution of differential equation system which is not homogenous and which is second degreed. In the fourth section, the way has been created. In this section; the definition of way irregularity has been made and it's accept that the way irregularity is not a function of chance. When Fourier Analysis has been applied to this chance function; way profile has been explained as the sum of endless harmonics. The definitions of Arithmetic average value, square average value, standard differentiation have been made and have been explained by mathematical terms. Power intensity of way irregularity has been defined several times and the definition made by Braun has been used in accounts. According to this, it's more meaningful to make the definition of a general way irregularity with way circular frekans ( Q, ) since time circular frekans (to ) depends on the movement speed due to the equation of m = vQ Way irregularity spectrum intensity depending on way circular frekans, ^(Q)=lim- (h(Q))2 (1) X is the amount of way gone during T period, and is found by v movement speed. X=vT (2) xiiFrom the comparison of spectrum intensity of way warning and spectrum of way irregularity; ** = (») = -**(*>) (3) v is obtained. Therefore, if </>h(Q) is defined; we may pass to h{(o) with the help of movement speed and we continue to count at a basis of time circular frekans. For finding of #k (Q), way irregularity measurements made by Brawn in M.I.R. A., have been used. The solutions of these measurements have been shown in double logarithmic axis in Figure 4.6 According to these measurements, it has been seen that; when spectrum intensity of way irregularity in double logarithmic axis, they have been represented well by lines. These lines may be defined by the equation of ^(n) = ^(Q0X^-r (4) Having that Ho, is the basic circular frekans, h (D.0 ) is the spectrum intensity of the way in this frekans. )dto (5) The frekans of this single harmony is taken as a middle frekans of this series. xiiiWay irregularity that has been given as power intensity may be become as the sum of harmonic function in endful numbers. For a good way irregularity; it's explained that 40 harmonics are enough, generally. In said program, 300 harmonics have been used. Power intensity spectrum has not been giving information for phase angles of harmonics to themselves. So; chance numbers creation function has been used in Q Basic Program and phase angles have been counted according to this. A problem in the method used in creation of the way, is how the parts said in power intensity function can be find. For there, two methods may be thought: a- Receiving of part widths as it will constitute a series with equal intervals. b- Receiving of part widths as it will constitute a series with logarithmic intervals. In the first method, due to the features of power intensity function; the effect of low frekans to square average; is bigger than of high frekans. In the second method, due to receiving of the areas of part equality, effects of harmonics in low and high frekans, to square average have been becoming equal. By receiving the frekans intervals equally, way irregularity profile and a way profile like and addition of small vibrations over a sinus wave that is large amplitudded, have been created. This situation has been showing itself with a curve with two extremum, in the classification of way heights. When power intensity analysis has been applied to created way irregularity, spectrum curve (as it is expected) has been increasing continuously. The showing of spectrum curve obtained, in double logarithmic axis, is a lire that will fit in to the power intensity spectrum. In the way profile created with logarithmic division, the effects of small vibrations added to a large sinus wave doesn't exist. Classification curve, is closer to the thesis that way irregularity in literature, is suitable to the Gauss Bell Curve. In contrasts when spectral analysis is compared wit the previous analysis, it becomes uncontinious. At the result of created ways, zigzag shape of the power intensity spectrum curve obtained in logarithmic division, may be explained that a power intensity spectrum value doesn't meet with every frekans point. There is a confusion about which division will be selected. But; at the end, dividing to the equal widths has been preferred due to the reasons that will be showed later. A division has been applied in the thesis of Niehus. In this thesis, suspension dry function effects have been searched, creation of the way has been made by the inverse application of FFT, and this means the division of integration interval to equal frekans intervals. xivEven if Niehus has been adding that irregularity is suitable to the Gauss differentiation in the doctoral thesis; curves given about this subject have been accepted as principle curve by not being counted with the created way. In the fifth and the last section; the comparison of continuous and fractionated lined shock-absorbers has been made. There are two important points in searching of the vehicle vibrations. There are way irregularity and the dynamic of vehicle vibration. In this search in three blocked model, input is the way irregularity and the output is stool, body movements and dynamic tire pressure. When; vibration comfort is searched in definition of way irregularity fih(Q.), evaluation is made over standard deviations. Standard deviations of acceleration of standard deviations of dynamic tire pressure are important criteria for searches. In three blocked system; the stochastic warning of non-linear shock-absorber, has been searched by using the program named as VIBRAT prepared by Prof. Dr. A. Işık ERZİ. In this program, simulation of three blocked vehicle has been counted in the created way (as equal frekans intervals). FFT has been applied to the results, standard deviation values have been counted by finding out the situations according to continuos and fractioned lined shock-absorbers. According to this, warning reply of fractioned lined shock absorber is a continuous curve and warning reply of continuous shock-absorber is a continuous curve. Stochastic warning repires have been seen as higher in fractioned lined shock absorbers in body and axis frekans. In Test F way creation program, with the effect of the speed, different ways for 10, 20, 30, 40, 50 m/s speeds have been created. For these ways created, by working the VIBRAT program in the given speeds, body, dynamic tire pressure standard deviations of continuous and fractioned lined shock absorbers have been counted. According to the values counted, as the speed raises standard deviation values have been increases. But the effects of high speeds in body, dynamic tire pressure have been staying same than low speed. The points of the vehicle in that the effect of the speed is felt, least, is at the body and most, is at the dynamic tire pressure. Effect of dimensionless extinction coefficient, has been counted as (D2) body, dynamic tire pressure standard deviations fro different dimensionless extinction coefficient between 0.1 and 0.37 in the program named VIBRAT in the way created. It's definite that the effect of D2 is at minimum between 0.15 and 0.22; like the effect of counted values to dimensionless extinction coefficient given as D2 =, 2 (6) 2V(Ci+c2)m2 With the increasing of dimensionless extinction coefficient in dynamic tire pressure; the effects will decrease. XVToll acceleration, body acceleration and dynamic tire pressure standard deviations have been counted for different fraction coefficients (kç/(kç+kb)) between 0 and 2 in program VIBRAT in the way created in searching of effects of fraction ratio of fractioned lined shock-absorbers. With the value counted; it's seen that fraction ratio value changes between 0 and 2. It's seen that stool, body accelerations and dynamic tire pressure standard deviations (0.5-1.5) take the minimum values in fraction ratios. Together with this; at a situation that the fraction ratio is one (1) standard deviations are rninimum. The situation that the fraction ratio is one (1); defines the feature of shock-absorber that it is a continuous shock-absorber. XVI

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