加入VIP 上传考博资料 您的流量 增加流量 考博报班 每日签到
   
主题 : 东大机械设计考试样卷
级别: 初级博友
显示用户信息 
楼主  发表于: 2007-11-14   

东大机械设计考试样卷

(1)     For a tight bolted connection with transverse load, the bolt is carried by     .  j<"nO(  
_{~] /k  
A. shear stress             B. tensile stress x|eeRf|  
K t#, ]]  
C. shear stress and tensile stress   D. shear stress or tensile stress N_75-S7Cm  
{F|48P;J  
(2)     For a tight bolted connection with axial tensile load F and preload , the resultant tensile force in the bolt is       . #ZiT-  
/)uM[ dnai  
A.   B.   C.   D. 0"[`>K~7a8  
c#xP91.m  
(3)     If the performance grade of a bolt is 6.8, then the yield limit stress of the bolt material is       MPa. wHsB,2H  
oQ+61!5>  
A. 600       B. 800       C. 680       D. 480 o07IcIo  
N<z`yV  
(4)     The lubricating method of a journal bearing is dependent on     . UEzi*"-v2  
,ZI\dtl  
A. average intensity of pressure p   B. circle velocity of journal v   C. pv   D. +yt6(7V*  
JhR W[~  
(5)     For a hydrodynamic radial journal bearing, the valid method for increasing is to     . hv)7H)|l~]  
L*?!Z^k  
A. increase relative clearance     B. increase oil supply `{FwTZ=6{  
,=[*Lo>O  
C. decrease     D. replace lubricating oil with lower viscosity <rK=9"$y(t  
SlT*C6f  
(6)     For a hydrodynamic radial journal bearing, the relative clearance is the ratio of     . k ~6- cx  
VTe.M[:  
A. diametral clearance and journal diameter   B. radial clearance and journal diameter heD,& OX  
|#5 e|z5(  
C. minimal clearance and diametral clearance |9NIGg'n  
J l7z|QS  
D. minimal clearance and journal diameter xNdIDj@  
-a) T6:e  
(7)     The axial preloading for rolling bearings is for _______. >BqCkyM9Kf  
uzorLeu  
A. increasing loading capacity     B. decreasing noise 9d[qh kPu)  
u2qV6/  
C. improving running precision   D. avoiding shaft displacement aMCO"66b  
Ge}$rLu]0  
(8)     The inner ring and outer ring of the     bearing are separable. y' tRANxQ  
|"}4*V_*  
A. deep-groove ball   B. self-aligning ball   C. tapered roller   D. self-aligning roller F ! )-|n}  
}bfn_ G  
(9)     In an important application, if the reliability of rolling bearings is increased to 95%, then the relation between the dynamic load rating relative to 95% reliability to the basic dynamic load rating C is _______. `facFt[\  
Ku%6$C!,  
A.     B.     C.     D. uncertain Fd !iQ  
IrO +5w  
(10)   For a cylindrical helical compressive spring, the maximal shear stress on spring wire happens at the ______. o8D{dS>,PL  
me'(lQ6^  
A. inner side of spring coil   B. outer side of spring coil 0(TvQ{  
+{&+L0DfH~  
C. center of spring wire     D. arbitrary position on spring wire -lp"#^ ;  
MuSaK %  
(11)   For a cylindrical helical compressive spring with working coils being 12, if the number of working coils is decreased by 3, then spring stiffness is _____. ;F,qS0lzE  
@DCJ}h ud  
A. decreased to 3/4 of the original value   B. decreased to 9/16 of the original value T 'i~_R6  
4I.1D2 1jA  
C. not changed         D. increased to 4/3 of the original value :1BM=_WwI  
z+6QZQk  
(12)   For a static balanced rigid rotor, its mass center is     located at the rotating axis. pDhY%w#  
nhT;b,G.Z  
A. certainly       B. not always       C. certainly not T/7vM6u  
iwkJ~(5z  
(13)   Shown in the figure is a cylindrical cam with uniform material, accurate manufacture and installation. When it rotates round the axis A-A, the cam is under the state of _________. afy/K'~  
:tlE`BIp  
A. static imbalance   B. static balance   C. complete imbalance   D. dynamic balance Gx;xj0-"  
7AeP Gr  
NY 4C@@"  
:R3P 58>  
(14)   The installation of flywheel in machinery is to       . n\* JaY  
kXCY))vnn  
A. eliminate speed fluctuation     B. realize steady running n`QO(pZ6+  
`;}H%  
C. decrease speed fluctuation     D. balance the inertia forces @4&, #xo  
,N0uR@GN  
(15)   In order to decrease the flywheel weight, the flywheel should be installed on the       。 !3QRzkJX~  
/Bm#`?(ia  
A. equivalent link               B. crankshaft with lower rotating speed Kc-4W6?$  
'Y ,1OK  
C. crankshaft with higher rotating speed   D. spindle of machinery k~R{Y~W!!  
$wgc vySx  
 ?;+^  
@$EjD3Z-  
2.     (7 points) In a tight bolted connection with axial tensile load, both the preload and the axial working load are constant. If the metal gasket between the connected components is replaced by a leather one, explain, with force-deformation diagram, the changes of the resultant tensile force in the bolt and residual compressive force on the connected components. }D Z)W0RDe  
CQ$::;  
">4PePt.n  
@~s~ /[  
w LpkUa  
_HLC>pH~#  
;m ' '9z)2  
 . uBO  
Ny.*G@&  
mF}c-  D  
[7'#~[a~  
2YE7 23H=Z  
uC- A43utv  
% Oz$_Xe  
phr2X*Z/)Y  
L+8=P<]  
Q,D0kS P  
J6eJIKK  
R$Zv0a&  
3R'.}^RN  
@+iC/  
L'13BRu`  
`'*F 1F  
"Ys_ \  
>~h>#{&  
xy$vYDAFw  
(L`l+t1  
f9vcf# 2  
_t$lcOT  
N )'8o}E  
3.     (10 points) Shown in the figure are the four structure schemes of the moving pulley shaft system in a lifting device. In each structure scheme, the lifting load is constant; the shaft diameter, shaft material and method of heat treatment are the same, respectively. ^OsA+Ea\  
`@4 2jG}*  
(1)   Determine the loads carried by the shaft and shaft types in each structure scheme. hK:#+hg,  
L& I` #  
(2)   Determine the stresses on the shaft and their changing characteristics in each structure scheme. ? UxG/]",  
{`+bW"9  
(3)   Compare the strength difference of the four shafts. o,g6JTh  
-" 2<h:#  
c zZrP"  
^:qpa5^"  
(a)             (b)           (c)             (d) dK:l&R  
WH{cJ7wCL  
imo'(j7  
<FXQxM5"  
J%:WLQo  
2v"wWap-+  
9c"0~7v  
on ]\J  
&i4 (s%z#  
=@bXGMsV!  
p +u{W"I`  
?whRlh  
2z.k)Qx!Z  
F7k4C2r  
G/x3wR  
;s}-X_O<  
4.     (8 points) Shown in the figure is a transmission layout for a belted conveyer. The arrangement for speed reduction is as follows: 1(motor)→2(chain drive)→3(gear reducer)→4(belt drive)→5(conveyer). Point out the unreasonable aspects of the arrangement and give a correct order represented with the drive number. H=JP3ID>{  
y}(_SU  
e1f^:C  
OhA^UP01-  
5.     (15 points) Shown in the figure, a helical gear shaft is supported by a pair of angular contact ball bearings (7208AC) with ; the radial loads acting on the bearings are , ; the externally axial load on the shaft is ; the rotating speed of the shaft is . Y}V)4j  
a(Gk~vD;"  
(1)   Find the axial forces on the two bearings: , . J,dG4.ht  
`~w%Jf  
(2)   If , find the equivalent dynamic loads of the two bearings: , . / t%"Dh 8x  
~NNaLl  
(3)   Find the bearing lives: , . pl1EJ <  
:kf3_?9rc  
@B>%B EC  
GI'&g@?u  
[)b/uR  
^)eessZ  
K8Kz  
K'{wncumQ  
1*c0\:BQ;z  
e+]YCp[(  
f:) K  
OTy 4"%  
O*+w_fox  
_If@#WnoyA  
K4VPmkG  
^<5^9]x  
%n V@'3EI  
BT*K,p  
R &-W_v+  
[{.\UkV@  
6.     (15 points) In a gear train shown in the figure, , , , , , , , , , the rotating direction of the gear 1 is as shown in the figure. Find both the magnitude and the direction of . ,XF6Xsg2  
JOE{&^j  
\:f}X?:  
D$^7Xhk  
ZP G8q  
L>R!A3G1  
7UEy L }N  
5G]#'tu  
k H( 3  
:XZJx gx  
?eg@ 7n  
N[?4yV2s  
7.     (15 points) Shown in Fig. (a) is the dynamically equivalent model of a mechanical system. The equivalent resistant moment of force is a given function of the rotating angle shown in Fig. (b) with the period . The equivalent driving moment of force is constant. The equivalent moment of inertia of the system is (constant). The average rotating speed of the equivalent link is . X|QX 1dl  
a1Y_0  
(1)   Find the equivalent driving moment of force. neMe<jr  
& /FA>  
(2)   Find the coefficient of speed fluctuation , maximal rotating speed and minimal rotating speed of the equivalent link. Gm?"7R.  
oCru5F  
(3)   If the allowable coefficient of speed fluctuation is , find the minimum moment of inertia of the flywheel on the crankshaft A of the equivalent link. 6T'43h. :  
P)o[p (  
#| e5  
zw;(:fgY#  
,;- cz-,  
0i1?S6]d-  
ovRCF(Og,  
f \%X 7.  
-wHGi  
uZ{xt6 f  
9~ .BH;ku  
T?$?5  
mwiPvwHrg  
~d1RD  
zqE Z+|c=  
6(;[ov1  
|H I A[.q  
53#5p;k  
rEyMSLN  
(IWd?,H,n  
h-u*~5dB<&  
w@D@,q'x  
}T(q"Vf~  
(?=(eo<N  
%JU23c*  
60 gn`s,,  
o`]FH _  
m^ &mCo,  
O? <_,-.  
{+59 YO  
-x5bdC(d  
H$'kWU*l  
lY8Qy2k|  
z~;qDf|I  
W_lNvzag  
w6Ny>(T/  
:Gk~FRA|  
f\_Q+!^  
0([jD25J!  
H`..)zL|  
P?-44m#  
s_+XSH[=f  
8.     (15 points) Point out all the mistakes in the shaft system shown in the figure and explain them with brief words.
评价一下你浏览此帖子的感受

精彩

感动

搞笑

开心

愤怒

无聊

灌水

  
描述
快速回复

验证问题:
免费考博网网址是什么? 正确答案:freekaobo.com
按"Ctrl+Enter"直接提交