2020 Experiment of Engineering Mechanics(Nanchang University) 最新满分章节测试答案

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本课程起止时间为:2020-12-09到2021-01-20
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01 Tensile test of metal materials（金属材料拉伸实验） Data Processing of Virtual Tensile Test of Low Carbon S

1、 问题:
答案: 【[190,200]】

2、 问题:(2) The yield limit of the material is ( ) MPa; (材料屈服极限是___MPa)
答案: 【[284,292]】

3、 问题:(3) The strength limit of the material is ( ) MPa; (材料的强度极限是___MPa)
答案: 【[413,422]】

4、 问题:(4) The percentage reduction of area is (  ). (断面收缩率是___)
答案: 【[0.6,0.61]】

5、 问题:(5) The percentage  elongation after fracture is (  ); (伸长率为___) 
答案: 【[0.20,0.22]】

【作业】01 Tensile test of metal materials（金属材料拉伸实验） Unit Exercises（单元练习）

1、 问题:In the tensile test, the low-carbon steel specimen shows the _ phenomenon firstly ,and it also shows the _ phenomenon(i.e. the reduction in area of the bar becomes clearly visible)after the strengthening stage. （在拉伸破坏实验中，低碳钢试样先发生 _ 现象，然后在 强化 阶段之后，发生____ 现象（即截面尺寸发生明显变小）。）A、yield,necking      （屈服，颈缩）B、necking,yield  （颈缩，屈服）C、break, yield  （破坏，屈服）D、yield,breakg  （屈服，破坏）
评分规则: 【 A
】

2、 问题:The cold-working hardening phenomenon will increase the _ of the material and decrease the __.（冷作硬化将提高材料的 _ ，而降低 _ 。）A、yield limit，fragility   （屈服极限，脆性）B、propotional limit,fragility （比例极限，脆性）C、yield limit，plasticity （屈服极限，塑性）D、propotional limit, plasticity （比例极限，塑性）
评分规则: 【 D
】

3、 问题:In the tensile experiment of low carbon steel specimen, the tensile curve can be generally divided into four typical stages:_, _, __, and__, （低碳钢拉伸试验中，其拉伸曲线一般可分为四个典型阶段，分别为_, _, __, 和_,）A、yield stage,elastic stage, strengthening stage,necking stage.（屈服阶段，弹性阶段，强化阶段，颈缩阶段）B、elastic stage, yield stage,strengthening stage,necking stage.（弹性阶段，屈服阶段，强化阶段，颈缩阶段）C、elastic stage, strengthening stage,yield stage,necking stage.（弹性阶段，强化阶段，屈服阶段，颈缩阶段）D、elastic stage,necking stage, yield stage,strengthening stage.（弹性阶段，颈缩阶段，屈服阶段，强化阶段）
评分规则: 【 B
】

4、 问题:Materials used in engineering can be divided into two categories according to their percent elongation after failure: _materials and _ materials, _is usually used as the boundary between the two types of materials.（工程中的材料可分为_材料和_材料两大类，通常以_作为定义两类材料的界限。）A、brittle,plastic,15% in elongation （脆性，塑性，伸长率15%）B、metallic,non-metallic,5% in elongation （金属，非金属，伸长率5%）C、metallic，non-metallic,15% in elongation （金属，非金属，伸长率15%）D、brittle,plastic,5% in elongation （脆性，塑性，伸长率5%）
评分规则: 【 D
】

5、 问题:For fragile materials without__, the _ corresponding to the _ strain of 0.2% is usually taken as the yield limit, which is called the nominal yield limit of the material and denoted by .（对于没有_塑性材料，通常以产生 0.2%的__应变时所对应的______作为屈服极限，称为材料的名义屈服极限，并用记号表示。）A、hardening stage,strain,plastic   （强化阶段，应变，塑性）B、yield stage,stress,plastic  （屈服阶段，应力，塑性）C、hardening stage,stress,elastic   （强化阶段，应力，弹性）D、yield stage,stress,elastic   （屈服阶段，应力，弹性）
评分规则: 【 B
】

6、 问题:The tensile experiments were carried out on low carbon steel specimens with the gauge length of 50 mm and 100 mm. The measured yield limits are  and  , and the percnet elongations are  and  respectively. Compare these two groups of values（    ）（用标距50 mm和100 mm的两种拉伸试样，测得低碳钢的屈服极限分别为 、，伸长率分别为和。比较两试样的结果是（   ））A、 = ; > .B、> ; > .C、 > ;= .D、 = ;= .
评分规则: 【 A
】

7、 问题:In the tensile test, modulus of elasticity can be obtained from the_ region in the stress-strain curve. It equals to the _of  the curve, and it is an indication of the of the material. （拉伸实验中，弹性模量可以通过应力-应变曲线的_ 范围得到，它等于曲线的_ ，是材料的__指标。）A、yield, slope,stiffness   （屈服，斜率，刚度）B、linear elastic, length,stiffness  （线弹性，长度，刚度）C、yield, slope,flexibility  （屈服，斜率，柔度）D、linear elastic, slope,stiffness  （线弹性， 斜率，刚度）
评分规则: 【 D
】

02 Compression test of metal materials（金属材料压缩实验） Data Processing of Virtual CompressionTest of Low C

1、 问题:(材料的强度极限是_____MPa)
答案: 【[298,302]】

2、 问题:(2) The elongation rate is (   ); （延伸率是____）
答案: 【[0.034,0.036]】

3、 问题:(3) The section shrinkage is (   ).  (断面收缩率为______ )
答案: 【[0.028,0.03]】

【作业】03 Torsion test of metal materials（金属材料扭转实验） Torsion test exercises （单元练习）

1、 问题:Please analyze the causes of  failure of low carbon steel and cast iron in torsion tests, according to their  failure modes.
评分规则: 【 Low-carbon steel samples fail in the cross-section plane because the shear stress reaches shear strength of the  material, and cast iron samples fracture along a 45°  spiral surface fracture, due to excessive tensile stress relative to its poor tensile strength.
】

2、 问题:What is the physical meaning of the shear modulus of elasticity G?
评分规则: 【 Answer: In the elastic stage, the shear stress is proportional to the shear strain and its proportional constant is the shear modulus of elasticity G.
】

3、 问题:Why is the torsion failure plane of low carbon steel coincident with that of Cross section, while that of cast iron is 45 spiral cross section with the axis of the specimen.
评分规则: 【  Answer：The torsion failure section of low carbon steel is coincident with the Cross section, which is caused by excessive shear stress, The cast iron specimen is 45 spiral fracture surface with the axis of the specimen, which is caused by excessive tensile stress.
】

4、 问题:Fill in the blanks with terms in Mechanics.For cast iron specimens, compression failure occurs at oblique sections with a 45-55 inclination to the cross section, which is caused by       stress. Torsional failure occurs on a spiral plane that is 45 degrees from the axis, and is caused by         stress.
评分规则: 【 Answer：shear，tensile5 pts per blank
】

5、 问题:Fill in the blanks.In the torsion test of low carbon steel, the angle of twist for gauge-length distance in the elastic stage is measured by              , including            ,            ,           ,                     etc.
评分规则: 【 Answer: the twist angle measuring device, chuck ,locating ring, measuring roll, photoelectric encoder5 Pts per blank
】

6、 问题:In the torsion test of low carbon steel, the angle of twist for gauge-length distance is measured. The gauge-length distance is set to be        mmA. 20 B. 30C. 40D. 50
评分规则: 【 D
】

7、 问题:Please choose the most appropriate option.Draw a small square on the surface of the round shaft as shown in the figure followed， When the shaft gets twisted, the square will become （     ）A、 to be square            B、to be rectangular C、to be Rhombic            D、 to be parallelogram
评分规则: 【 B
】

03 Torsion test of metal materials（金属材料扭转实验） Data Processing of Virtual Torsion Test of Low Carbon S

1、 问题:（低碳钢剪切弹性模量G是____GPa）
答案: 【[87,92]】

2、 问题:(2) The shear yield limit is (   ) MPa . ( 剪切屈服极限为___MPa )
答案: 【[154,180]】

3、 问题:(3) The shear strength limit is (   ) MPa. ( 剪切强度极限为____MPa )
答案: 【[470,486]】

4、 问题:(4) The theoretical value of material shear modulus of elasticity is (   ) GPa. ( 材料剪切弹性模量的理论值为____GPa )
答案: 【[78,82]】

5、 问题:(5) The relative error between the test value and the theoretical test of the shear modulus of elasticity is (       )%.（note：absolute value） ( 剪切弹性模量测量值与理论值相对误差的绝对值为____% )
答案: 【[8,14]】
分析：【取绝对值】

04 Installation of Strain gages（应变片粘贴实验） exercises of unit 4

1、 问题:The sensitivity factor K of the strain gauge refers to （应变片的灵敏度系数是指____）
选项：
A:resistance value (电阻值)
B:Relative resistance change of strain gauge caused by unit strain (单位应变引起的应变片相对电阻变化)
C:The relative change of the cross-sectional area of the strain gauge wire (应变片导线截面积的相对变化)
D:Relative change of resistance value of strain gauge wire (应变片电阻值的相对变化)
答案: 【Relative resistance change of strain gauge caused by unit strain (单位应变引起的应变片相对电阻变化)】

2、 问题:Four resistance strain gauges R1, R2, R3 and R4 are attached to four points of a component. The strains of the four points measured by the single-point method(half-bridge with temperature compensation ) are ε1 = 300με, ε2 = -300με, ε3 = 400με, ε4 = -400με. If these four strain gauges are connected into a full bridge as shown in the figure followed, the reading will be (         )  με.  (四个电阻应变片R1，R2，R3和R4连接成四点的桥路。 用单点法（带温度补偿的半桥）测得的四个点的应变为ε1=300με，ε2=-300με，ε3=400με，ε4=-400με。 如果按下图所示将这四个应变仪连接到一个全桥中，则读数将为____με。)
选项：
A:1400
B:600
C:800
D:0
答案: 【1400】

3、 问题:The strain measured by the resistance strain gauge is 
选项：
A:the average strain in sensitive grid area
B:the average strain in base area of the strain gauge
C:the strain at the center of the sensitive grid
D:the average strain at the two ends of the sensitive grid length
答案: 【the average strain in sensitive grid area】

4、 问题:What the resistance strain gauge measures is  （       ）
选项：
A:Shear strain
B:Shear stress
C:Linear strain
D:Normal stress
答案: 【Linear strain】

5、 问题:Two strain gauges R1 and R2 on the tensile test piece shown in the following figure, are perpendicular to each other. using the half-bridge method, R1 is connected to the AB bridge, and R2 is connected to the BC bridge. Apply a tensile force F.Tthe strain values of R1 and R2 are ε1 and ε2, respectively. If the Poisson’s ratio of the material is μ,  the reading strain εr = 
选项：
A:ε1 + ε2
B:(1+μ) ε1 
C:(1-μ) ε1 
D:(1+μ) ε2
答案: 【(1+μ) ε1 】

6、 问题:When measuring strain with electronic methods, in order to eliminate the influence of ambient temperature changes ,             compensation need to be performed to get accurate strain produced by force.
答案: 【temperature】

7、 问题:A strain gauge is installed on a compressed specimen. Its original resistance is 120Ω and a gage factor K = 2.06. If the strain of the test part along the gage direction is -1000×10-6, the resistance value of the strain gauge should be                           Ω 
答案: 【[119.7,119.8]】

8、 问题:The three basic requirements that the temperature compensation plate must meet are:(1) The               of the compensation plate should be the same as the test part. and plate are not               ;(2) The compensating gauge attached to it and the working gage are at the same                  environment;(3) Compensating gage and working gauge should be from the same               and are of the same         .
答案: 【material ,stressed,temperature,batch,model】

9、 问题:In engineering tests, the three common bridges used for strain measuring are: _, __ and _____.
答案: 【quarter bridge,half bridge,full bridge】

10、 问题:The sensitivity coefficient of the strain gauge Ks = 2.00, the sensitivity coefficient of the strain gauge Kg = 2.08, when the reading on the strain instrument ε = 400με, the actual strain value of the strain gage is               με.
答案: 【[384,386]】

【作业】04 Installation of Strain gages（应变片粘贴实验） exercises of unit 4 （单元测试）