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     . 7<W7pXDp  
sxq'uF(K  
A. shear stress             B. tensile stress y}NBJ  
Y {]RhRR  
C. shear stress and tensile stress   D. shear stress or tensile stress $7q'Be@{  
!C&!Wj  
(2)     For a tight bolted connection with axial tensile load F and preload , the resultant tensile force in the bolt is       . XP Nk#"  
h(aF>a\Z  
A.   B.   C.   D. |2,'QTm=  
Xj:?V;  
(3)     If the performance grade of a bolt is 6.8, then the yield limit stress of the bolt material is       MPa. $i@~$m7d-  
$x T'cl/IH  
A. 600       B. 800       C. 680       D. 480 ^:Vwblv(  
1n7tmRl  
(4)     The lubricating method of a journal bearing is dependent on     . Xrpzc~(  
+(d\`{A  
A. average intensity of pressure p   B. circle velocity of journal v   C. pv   D. Q /T\Rr_d  
#`P4s>IL1  
(5)     For a hydrodynamic radial journal bearing, the valid method for increasing is to     . {b4+ Yc  
bg$df 0  
A. increase relative clearance     B. increase oil supply ax7]>Z=%d"  
Ql-RbM  
C. decrease     D. replace lubricating oil with lower viscosity OA#AiQUR  
E7E>w#T5  
(6)     For a hydrodynamic radial journal bearing, the relative clearance is the ratio of     . X5kIM\  
3DRXao  
A. diametral clearance and journal diameter   B. radial clearance and journal diameter 7<&CN0&  
_iBNy   
C. minimal clearance and diametral clearance GJW>8*&&(  
h amn9  
D. minimal clearance and journal diameter BR5r K  
:4|W;Lkd!  
(7)     The axial preloading for rolling bearings is for _______. (7w`BR9B  
e=KA|"v xh  
A. increasing loading capacity     B. decreasing noise aL@myq.  
|eIEqq.Eb  
C. improving running precision   D. avoiding shaft displacement ?[Xv(60]  
MH|!tkW>:  
(8)     The inner ring and outer ring of the     bearing are separable. FJl#NOp&  
xcfEL_'o  
A. deep-groove ball   B. self-aligning ball   C. tapered roller   D. self-aligning roller "`Q~rjc$2  
yLFc?{~7  
(9)     In an important application, if the reliability of rolling bearings is increased to 95%, then the relation between the dynamic load rating relative to 95% reliability to the basic dynamic load rating C is _______. F8S -H"  
+ZeHZjd  
A.     B.     C.     D. uncertain S0C 7'H%?#  
n2\;`9zm  
(10)   For a cylindrical helical compressive spring, the maximal shear stress on spring wire happens at the ______. NDLk+n  
Iy8>9m'5  
A. inner side of spring coil   B. outer side of spring coil  }6SfI;  
Ht,_<zP;  
C. center of spring wire     D. arbitrary position on spring wire 3uO#/EbS  
co<-gy/mCR  
(11)   For a cylindrical helical compressive spring with working coils being 12, if the number of working coils is decreased by 3, then spring stiffness is _____. wzhM/Lmo\z  
kxU <?0  
A. decreased to 3/4 of the original value   B. decreased to 9/16 of the original value 7(B|NYq  
p$^}g:  
C. not changed         D. increased to 4/3 of the original value Z3E957}  
490gW?u  
(12)   For a static balanced rigid rotor, its mass center is     located at the rotating axis. cwi HHf>  
U^<\'`  
A. certainly       B. not always       C. certainly not =qH9<,p`H  
y&T(^EA;  
(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 _________. c%-s_8zvi  
pE(\q+1<  
A. static imbalance   B. static balance   C. complete imbalance   D. dynamic balance g'G%BX  
@cNBY7=  
(.Tkv Uj`  
[V'3/#Z  
(14)   The installation of flywheel in machinery is to       . vUD,%@k9  
t]1j4S"pm  
A. eliminate speed fluctuation     B. realize steady running EacqQFErl  
|}zvCD  
C. decrease speed fluctuation     D. balance the inertia forces 6FPGQ0q  
;!U`GN,tH  
(15)   In order to decrease the flywheel weight, the flywheel should be installed on the       。 O H~X~n-Z  
sIQd }  
A. equivalent link               B. crankshaft with lower rotating speed JJJlgr]#  
( XY YbP  
C. crankshaft with higher rotating speed   D. spindle of machinery M,1Yce%+}  
<4s$$Uw}6%  
h*2Q0GRX  
g0t$1cUR  
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]7@!qy  
"-JJ6Bk  
0JTDJZOz@#  
+k]9n*^uz  
6b+\2-eq  
F[/Bp>P7  
!FOPFPn  
.um]1_= \  
K d}cf0  
`?VtB!p@x=  
U085qKyCw  
yv| |:wZC  
l +RT>jAmK  
zt{?Nt b  
K~**. NF-n  
s hjb b  
vwQ Y_J8  
m@o/W  
j3|Ek  
+@D [%l|  
5|Yp kY  
[?u iM^&  
GKdQ   
Q" BIk =  
aRg/oA4}  
vum6O 3  
TV)bX  
[*zB vj}G  
qPsf`nI7  
Arh0m. w  
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. nxH=Ut7{  
I]N?}]uZ  
(1)   Determine the loads carried by the shaft and shaft types in each structure scheme. N{v <z 6  
KP" lz  
(2)   Determine the stresses on the shaft and their changing characteristics in each structure scheme. *BzqAi0  
x zmg'Br  
(3)   Compare the strength difference of the four shafts. "w ] Bq0  
B-`d7c5  
$/</J]2`;  
W/COrgbW  
(a)             (b)           (c)             (d) F9(*MP|  
y]$%>N0vLX  
V'(yrz!   
\zioIfHm  
``?] 13XjK  
M:V'vme)+  
RWM9cV5  
F|\^O[#R  
z0[_5Cm/  
m'D_zb9+  
?HT +| !4p  
aOZSX3;wg  
x=(y  
. 7WNd/WG  
e<wA["^  
i> Wsc?  
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. ,e\'Y!'  
( )K,~  
._2#89V  
S8-3Nv'  
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 . .}'49=c  
NN(ZH 73  
(1)   Find the axial forces on the two bearings: , . n.+%eYM<  
i*-[-hn-V  
(2)   If , find the equivalent dynamic loads of the two bearings: , . hgt@Mb   
-Zs.4@GH  
(3)   Find the bearing lives: , . tf?syk+jB7  
f.Wip)g  
SM%N ]/@U  
FKhmg&+>  
}G8gk"st  
)UBU|uYR\  
P`ZzrN  
c8uFLM j  
]B8`b  
=j,2  
}_,\yC9F  
m ab921-n  
1!N|a< #  
(i..7B:  
QT\||0V~p  
BQ8vg8e]B  
].AAHu5  
o2AfMSt.  
NUSb7<s,&Y  
HL8onNq  
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 . &m{SWV+   
244[a] %&;  
\mK;BWg)  
.wH`9aq;5@  
"Zh3,  
|DUW B;  
pW[KC!  
=6.4  
!= uaB.  
e4h9rF{Cxn  
RIm8PV;N  
0|i3#G_~  
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 . #gq!L  
*F:)S"3_~e  
(1)   Find the equivalent driving moment of force. =Ch^;Wyt  
yg@8&;bP`  
(2)   Find the coefficient of speed fluctuation , maximal rotating speed and minimal rotating speed of the equivalent link. !B*l'OJw  
o;kxu(>yL'  
(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. 5^5hhm4  
;_~9".'<d  
1m~-q4D)V  
<5 )F9.$  
ln1!%B;  
Q\W?qB_  
]t"X~  
f1$'av  
f2LiCe.?  
+RBX2$kB  
\\Z Ci`O  
gyz_$T@x  
%,UTFuM`  
JP,yRb\  
>bFrJz}  
L$z(&%Nx  
z&c|2L-u6  
Ie]k/qw+Y  
6Z l#$>P  
vR7S !  
7G+E+A5o&  
_iF*BnmN  
^WkqRs  
` 7P%muY.  
5AK@e|G$w  
YuUJgt .1  
z"c,TlVN3  
VkkC;/BBW  
u]*f^/6Q  
L0)w~F ?m  
J9/EJ'My  
< V*/1{  
.lAPlJOO  
)UtK9;@"  
e>m+@4*sn  
wBJ|%mc3TA  
!>#gm7  
\S_A e;  
. H}R}^  
mM r$~^P:  
^3ai}Ei3  
:PK2! 0nK  
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:
免费考博论坛网址是什么? 正确答案:freekaobo.com
按"Ctrl+Enter"直接提交