中国大学Theory of Machine and Mechanisms期末答案(慕课2023课后作业答案)
19 min read中国大学Theory of Machine and Mechanisms期末答案(慕课2023课后作业答案)
Chapter 1 Unit Test
1、中国作业The大学答案答案 term “synthesis” differs from “design” which is the process of prescribing the size, shape, material compositions, arrangements of parts, calculations of strength, methods of production, etc.
2、Mechanisms used in machines which have different functions and profiles may be the same.
3、期末The慕课 radii of the holes and the cross-section areas of the links are the kinematics dimensions.
4、Machine is 课后a mechanical system that can transmit or transform energy, materials or information.
5、Almost all machines contain only one basic mechanism.
Chapter 2 Structural Analysis 中国作业of Planar Mechanisms
Chapter 2 Unit Test
1、In the following choices,大学答案答案 which one is a planar higher pair?
A、
B、期末
C、慕课
D、课后
2、中国作业In the following single-cylinder four-stroke internal combustion engine,大学答案答案 which part is an output link?
A、2
B、期末3
C、慕课4
D、课后5
3、In the following mechanisms, which one has not redundant DOF.
A、
B、
C、
D、
4、In the following mechanism, the DOF of the mechanism is .
A、0
B、1
C、2
D、3
5、In the following mechanisms, whose DOF differ from others.
A、
B、
C、
D、
6、If the compound pair contains K links, the number of revolute joints is .
A、K-2
B、K-1
C、K
D、K+1
7、In the following mechanism, it has redundant constraints.
A、0
B、1
C、2
D、3
8、In the following mechanism, in order to have a determined motion, the mechanism needs to have driving link(s).
A、1
B、2
C、3
D、4
9、In the following choices, which one cannot be deleted before the calculation of the DOF of a mechanism?
A、compound pairs
B、passive DOF
C、redundant constraints
D、all of the above
10、In the following mechanism, the mechanism has redundant constraint(s) and DOF.
A、2，3
B、2，1
C、0，3
D、0，1
Chapter 3 Kinematic Analysis of Planar Mechanisms
Chapter 3 Unit Test
1、How many instant centers in the mechanism below?
A、5
B、6
C、7
D、8
2、How many instant centers in the mechanism below?
A、3
B、4
C、5
D、6
3、The cam mechanism below has the dimensions: R=50mm, lOA=20mm,lAC=80mm, j1=90 degree. Cam 1 rotates at a constant angular velocity of w1 = 10 rad/s. counterclockwise. P12 is an instant center. The angular velocity w2 of follower 2 is equal to:
A、
B、
C、
D、
4、The velocity vector polygon and acceleration vector polygon of the link are similar to the shape of the link.
5、The method of instant center can be applied to calculate velocity and acceleration.
6、Kinematic analysis only involves the analysis of velocity and acceleration.
7、For a high pair, the contact point is the instant center.
8、For a planar mechanism, the number of instant centers can be calculated by the equation , where k is the number of links in the mechanism.
9、Instant centers can be classified into _______ and _______.
10、The instant center of a revolute pair in a planar mechanism is _________.
11、Relative motion graphic method is based on two theories,_____________ and ___________.
12、For relative motion graphic method, the velocity vector starting from the polar point is __________, while the velocity vector connecting two kinematic pairs is ________.
13、As for the sliding pair in a planar mechanism, the location of instant center is located at ______________.
Chapter 4 Planar Linkage Mechanisms
Chapter 4 Unit Test
1、Determine the type of the linkage and type of the two side links AB and DC (crank or rocker) according to the Grashof criterion. Can the coupler BC rotates 360° with respect to the frame? LAB = 80mm, LBC = 20mm, LDC = 45mm, LAD = 60mm
A、Double crank mechanism
B、Double rocker mechanism
C、Crank -rocker mechanism
D、Slider-crank mechanism
2、Determine the type of the linkage and type of the two side links AB and DC (crank or rocker) according to the Grashof criterion. Can the coupler BC rotates 360° with respect to the frame? LAB = 20mm, LBC = 45mm, LDC = 70mm, LAD = 90mm
A、Double crank mechanism
B、Double rocker mechanism
C、Crank -rocker mechanism
D、Slider-crank mechanism
3、Find the name of the mechanism
A、Slider-crank mechanism
B、Rotating guide-bar mechanism
C、Swing guide-bar mechanism
D、Crank and oscillating block mechanism
4、In a revolute four-bar linkage in the following figure,LBC=100mm, LCD=80mm,LAD=110mm. Find the range of the values for the length of link AB if the linkage is a crank-rocker mechanism with crank AB, ______________
A、
B、
C、
D、
5、In a revolute four-bar linkage in the following figure, LBC=100mm, LCD=80mm,LAD=110mm. Find the range of the values for the length of link AB if the linkage is a double-rocker mechanism, and AB is the shortest link, ____
A、
B、
C、
D、
6、In a revolute four-bar linkage in Fig. 4-1, LBC=100mm, LCD=80mm,LAD=110mm. Find the range of the values for the length of link AB if the linkage is a double-rocker mechanism, and AB is the longest link, ______
A、
B、
C、
D、
7、In a revolute four-bar linkage in Fig. 4-1, LBC=100mm, LCD=80mm,LAD=110mm. Find the range of the values for the length of link AB if the linkage is a double-rocker mechanism, and AB is neither the shortest nor the longest link, ______
A、
B、
C、
D、
8、Determine the type of the linkage and type of the two side links AB and DC (crank or rocker) according to the Grash of criterion. The coupler BC rotates 360° with respect to the frame. LAB = 45mm, LBC = 50mm, LDC = 60mm, LAD = 20mm
9、The function of a linkage mechanism is to transform the Continuous rotation into continuous rotation, with a constant or variable angular velocity ratio.
10、The function of a linkage mechanism is to transform the Continuous rotation into oscillation or reciprocation (or the reverse), with a constant or variable velocity ratio.
11、The planar linkage mechanisms have the advantage of great ability to trap lubricant between enveloping surfaces. Therefore, the contact pressure and wear between two links are low.
12、For the planar linkages, the balance design and analytical calculation are very easy.
13、ABCD is a crank -rocker mechanism,,shown in Fig.1 If the side link DC is a driver, γis γmin at this position, shown in Fig.2. Fig. 1 Fig. 2
14、This mechanism has quick-return characteristics.
15、An offset slider-crank mechanism is shown in following figure. the crank AB is a driver which runs at a constant speed. lAB=e=10mm, lBC=50mm. (1)Calculate the minimum and maximum pressure angle, amin= ____°and amax=_____°. (2)If the slider needs a higher speed in its rightward stroke than in leftward stroke, which rotation direction will the crank AB take?(clockwise or anticlockwise) ________ (3) Find the crank acute angle between two limiting positions q=_____°
16、In a revolute four-bar linkage in the following figure, LBC=100mm, LCD=80mm,LAD=110mm. Can the linkage be a double-crank mechanism by adjusting the length of LAB ？(Yes or No)____________Why?___________
Chapter 5 Cam Mechanisms
Chapter 5 Unit Test
1、Cam mechanisms can be classified By the Shape of the Follower End as
A、Knife-edge follower
B、Roller follower
C、Flat-faced follower
D、Force closure
2、Cam mechanisms can be classified By the Form of Closure as
A、Force closure
B、Form closure
C、Roller follower
D、Flat-faced follower
3、Find the Follower Motion Curves in Common Use
A、Constant Velocity Motion
B、Constant Acceleration and Deceleration Motion
C、Cosine Acceleration Motion
D、Sine Acceleration Motion
E、Polynomial Motion
4、Choose the motion curve which has a soft impulse
A、Constant Velocity Motion
B、Constant Acceleration and Deceleration Motion
C、Cosine Acceleration Motion
D、Cycloidal Motion
E、Polynomial Motion
5、Find the pressure angle for the plate cam with flat-faced follower.
A、0°
B、70°~80°
C、Pressure angle varies during motion
D、Pressure angle is a constant during motion
6、Choose the motion curve is suitable for high speed operation.
A、Constant Velocity Motion
B、Constant Acceleration and Deceleration Motion
C、Cosine Acceleration Motion
D、Cycloidal Motion
E、Polynomial Motion
7、The tangential distance from the center of the cam to the center line of the follower called the offset e.
8、The greatest distance through which the follower moves is known as the total follower travel, or the lift.
9、While designing the cam profile, we may use the principle of inversion. In this invert the situation, the cam is assumed to be fixed, the frame and follower will rotate around the cam center in the direction of the cam.
10、Pressure angle ? for the plate cam with knife-edge translating follower varies during motion.
11、The larger the value of Pressure angle is, the larger the side-thrust is. If the side-thrust is too large the follower may jam in the guide-way. So it is necessary to control the value of the maximum pressure angle αmax.
12、The smaller the value of the Radius of base circle is, the larger the value of the pressure angle αmax will be.
Chapter 6 Gear Mechanisms
Chapter 6 Unit Test
1、Which statement about the helical gear is wrong?
A、The parameters in normal profile of the helical gears are standardized.
B、Comparing with the spur gears, the helical gears have a less contact ratio.
C、The directions of helix angle for a pair of external gears in mesh are opposite.
D、Undercutting can be avoided by Increasing the teeth number
2、which factor is irrelevant to the contact ratio of spur gears?
A、Teeth number
B、Module
C、The radius of addendum circle
D、Center distance
3、which statement below is wrong?
A、Undercutting can be avoided by decreasing the teeth number.
B、Undercutting can be avoided by using nonstandard cutters.
C、Undercutting can be avoided by addendum modification.
D、Undercutting can be avoided by Increasing the teeth number.
4、For a given parameters, which kind of gears have a higher load capacity?
A、Positive modified gears
B、Negative modified gears
C、Standard gears
D、Not sure
5、What are the correct meshing conditions for worm and worm wheel?
A、
B、
C、
D、
6、Comparing with the spur gears, what are the advantages of helical gears?
A、Helical gears operate more smoothly and silently.
B、High contact ratio and heavier load capability.
C、No thrust along gear axis.
D、Less sensitive to undercutting
7、Gear mechanisms can be used to transmit motion between ________.
8、If direction of teeth is inclined to the axis of rotation, the gear is called ____.
9、_____ gear mechanisms can be used to transmit motion between shafts whose axes intersect or skew.
10、In order to satisfy the fundamental law of gearing, _____ is chosen as the teeth profile.
11、The rotation of two circular gears can be treated as the pure rolling of two _____.
Chapter 7 Gear Trains
Chapter 7 Unit Test
1、In the gear train shown below, tooth numbers are Z1=40, Z2=40, Z3=50, Z1’=20, Z3’=80. All the gears have the same module. i1H = ().
A、20/25
B、25/17
C、30/17
D、17/30
2、In the given gear train, Z1 =Z2’=Z4=20, Z2=Z3=60, Z5=40. The transmission ratio i15 = ().
A、10
B、14
C、16
D、18
3、In the given gear train, Z1 =24, Z2=33, Z2’=21, Z3=36, Z3’=18, Z5=78. Please determine the tooth number of the gear 4, and the transmission ratio i15 = ().
A、81/7
B、-81/7
C、-41/7
D、41/7
4、Transmission ratio indicates both ______ and ____.
5、If the DOF of the epicyclic gear is 1, it is called ______; if the DOF of the epicyclic gear is 2, it is called ______.
6、The structure of the epicyclic gears includes _________ and _________.
7、When designing planetary gear trains, the four conditions must be satisfied, such as _____________, ______________, ____________________, and _______________.
Chapter 8 Other Mechanisms in Common Use
Chapter 8 Unit Test
1、One kinematic pair can connect only two links.
2、In a closed chain, every link has at least two pair-elements.
3、Only when the number of driving links is equal to the DOF of the mechanism, the mechanism can move.
4、There can only be one driven link in a mechanism.
5、When the DOF of a mechanism is calculated, redundant constraints should be deleted. Therefore, the redundant constraints should be omitted from real mechanism.
6、A passive DOF does not change the output motion of a mechanism.
7、DOF is the number of independent parameters to define uniquely the locations of all moving links within a mechanism.
8、A passive and redundant constraints must be deleted before the calculation of the DOF of a mechanism.
9、An output link can be either a driving link or a driven link.
10、Redundant constraints can improve the rigidity of a mechanism, improve the force condition in links, and overcome any undetermined motion.
Chapter 9 Dynamic Analysis of Planar Mechanisms
Chapter 9 Unit Test
1、For the slider crank mechanism below, the dashed circle represents the friction circle. If the masses of the links are neglected, the direction of angular velocity w21 and w23 are ().
A、clockwise, anti-clockwise
B、anti-clockwise, clockwise
C、clockwise, clockwise
D、anti-clockwise, anti-clockwise
2、A four-bar linkage mechanism is shown below, M1 and M3 are applying on the link1 and link 3, w1 is the angular velocity of link 1. the dashed circle represents the friction circle. If the masses of the links are neglected, the direction of angular velocity w21 and w23 are ().
A、clockwise, anti-clockwise
B、anti-clockwise, clockwise
C、clockwise, clockwise
D、anti-clockwise, anti-clockwise
中国大学Theory of Machine and Mechanisms
机械学与机构学，通常被称为机械原理或机构学，是一门研究机械运动和力学原理的学科。中国大学的Theory of Machine and Mechanisms课程是机械工程专业本科阶段的必修课程，涵盖了机构学中的基本概念、机构设计和分析、运动学与动力学等方面的内容。
课程设置
中国大学的Theory of Machine and Mechanisms课程一般分为两个部分，即理论教学和实践教学。
理论教学
理论教学主要包括机构学中的基本概念、机构设计和分析、运动学与动力学等方面的内容。学生需要掌握机构学中的基本概念和术语，理解机构的运动特性和力学原理，并具备机构设计和分析的能力。
实践教学
实践教学包括实验、课程设计和实习等方面的内容。学生需要通过实验，加深对机械运动和力学原理的理解；通过课程设计，掌握机构设计和分析的能力；通过实习，了解机械行业的实际应用和发展趋势。
重点内容
中国大学的Theory of Machine and Mechanisms课程的重点内容包括以下几个方面。
机构学中的基本概念
机构学是机械学的重要分支，主要研究机械运动的形式、机械系统的结构和运动特性等问题。在学习Theory of Machine and Mechanisms课程时，学生需要了解机构学中的基本概念，如机构、连杆、摆动轴等，掌握它们的定义和特性。
机构设计和分析
机构设计和分析是机构学的核心内容，在中国大学的Theory of Machine and Mechanisms课程中占据重要的地位。学生需要掌握机构设计和分析的基本方法和技巧，如机构的结构设计、机构的运动分析、机构的力学分析等。
运动学和动力学
机械运动的研究可以分为运动学和动力学两个方面。运动学研究机械系统运动的形式、速度和加速度等问题；动力学则研究机械系统的受力和运动学参数之间的关系。在学习Theory of Machine and Mechanisms课程时，学生需要掌握运动学和动力学方面的基本概念和方法，如速度和加速度分析、牛顿定律、能量守恒等。
课程评价
中国大学的Theory of Machine and Mechanisms课程是机械工程专业本科阶段的必修课程，是培养机械工程师的重要环节。该课程的教学内容丰富、实用性强，能够有效提高学生的机械学和机构学水平。同时，中国大学的Theory of Machine and Mechanisms课程教师团队严谨、敬业，为学生提供了优质的教育资源。
总的来说，中国大学的Theory of Machine and Mechanisms课程是一门优秀的课程，在机械工程专业的教育中发挥着重要作用。
