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GB/T 1040 consists of the following parts, under the general titel Plastics — Determination of Tensile Properties:
— Part 1: General Principles;
— Part 2: Test Conditions for Moulding and Extrusion Plastics;
— Part 3: Test Conditions for Films and Sheets;
— Part 4: Test Conditions for Isotropic and Orthotropic Fibre-reinforced Plastic Composites;
— Part 5: Test Conditions for Unidirectional Fibre-reinforced Plastic Composites.
This part is Part 1 of GB/T 1040.
This part is drafted in accordance with the rules given in the GB/T 1.1-2009.
This part replaces GB/T 1040.1-2006 Plastics — Determination of Tensile Properties — Part 1: General Principles in whole. For the purpose of this part, the following technical deviations have been made with respect to the GB/T 1040.1-2006 (the previous edition):
— Poisson’s ratio has been modified;
— defnitions and methods have been optimized for computer controlled tensile test machines;
— the preferred gauge length for use on the multipurpose test specimen has been increased from 50 mm to 75 mm. This is used especially in GB/T 1040.2;
— nominal strain of tensile has been modified;
— addition of method for calculation of standard strain;
— removal of Annex A (Informative) Young's Modulus and Related Calues;
— addition of Annex A (Informative) Determination of Strain at Yield;
— addition of Annex B (Informative) Extensometer Accuracy for the Determination of Poisson’s Ratio;
— addition of Annex C (Informative) Calibration Requirements for the Determination of the Tensile Modulus.
This standard is identical with International Standard ISO 527-1:2012 Plastics — Determination of Tensile Properties — Part 1: General Principles.
The Chinese documents in consistency with corresponding international normative references in this part, are as follows:
GB/T 2918-2018 Plastics — Standard Atmospheres for Conditioning and Testing (ISO 291:2008, MOD)
GB/T 2941-2006 Rubber — General Procedures for Preparing and Conditioning Test Pieces for Physical Test Methods (ISO 23529:2004, IDT)
This part was proposed by China Petroleum and Chemical Industry Federation.
This part is under the jurisdiction of National Technical Committee 15 on Plastic of Standardization Administration of China, Subcommittee 4 on Universal Method Product (SAC/TC 15/SC 4).
This part replaces GB/T 1040.1-2006.
The previous editions of GB/T 1040.1-2006 are as follows:
— GB/T 1039-1979, GB/T 1039-1992;
— GB/T 1040-1979, GB/T 1040-1992.
Plastics — Determination of Tensile Properties — Part 1: General Principles
1 Scope
This part of GB/T 1040 specifies the general principles for determining the tensile properties of plastics and plastic composites under defined conditions. Several different types of test specimen are defined to suit different types of material which are detailed in subsequent parts of this standard.
The methods are used to investigate the tensile behaviour of the test specimens and for determining the tensile strength, tensile modulus and other aspects of the tensile stress/strain relationship under the conditions defined.
The methods are selectively suitable for use with the following materials:
— rigid and semi-rigid (see 3.12 and 3.13, respectively) moulding, extrusion and cast thermoplastic materials, including filled and reinforced compounds in addition to unfilled types; rigid and semi-rigid thermoplastics sheets and films;
— rigid and semi-rigid thermosetting moulding materials, including filled and reinforced compounds; rigid and semi-rigid thermosetting sheets, including laminates;
— fibre-reinforced thermosets and thermoplastic composites incorporating unidirectional or non-unidirectional reinforcements, such as mat, woven fabrics, woven rovings, chopped strands, combination and hybrid reinforcement, rovings and milled fibres; sheet made from pre-impregnated materials (prepregs),
— thermotropic liquid crystal polymers.
The methods are not normally suitable for use with rigid cellular materials, for which ISO 1926 is used, or for sandwich structures containing cellular materials.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 12160-2002 Calibration of Extensometers Used in Uniaxial Testing (ISO 9513:1999, IDT)
GB/T 16825.1-2008 Verification of Static Uniaxial Testing Machines — Part 1: Tension/Compression Testing Machines — Verification and Calibration of the Force-measuring System (ISO 7500-1:2004, IDT)
ISO 291 Plastics — Standard Atmospheres for Conditioning and Testing
ISO 2602 Statistical Interpretation of Test Results — Estimation of the Mean — Confdence Interval
ISO 16012 Plastics — Determination of Linear Dimensions of Test Specimens)
ISO 20753 Plastics — Test Specimens
ISO 23529 Rubber — General Procedures for Preparing and Conditioning Test Pieces for Physical Test Methods)
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
gauge length
L0
initial distance between the gauge marks on the central part of the test specimen
Note 1: It is expressed in millimeters (mm).
Note 2: The values of the gauge length that are indicated for the specimen types in the different parts of GB/T 1040 represent the relevant maximum gauge length.
3.2
thickness
h
smaller initial dimension of the rectangular cross-section in the central part of a test specimen
Note: It is expressed in millimeters (mm).
3.3
width
b
larger initial dimension of the rectangular cross-section in the central part of a test specimen
Note: It is expressed in millimeters (mm).
3.4
cross-section
A
product of initial width and thickness, A = bh, of a test specimen.
Note: It is expressed in square millimeters, (mm2)
?
3.5
test speed
v
rate of separation of the gripping jaws
Note: It is expressed in millimeters per minute (mm/min).
3.6
stress
σ
normal force per unit area of the original cross-section within the gauge length
Note 1: It is expressed in megapascals (MPa)
Note 2: In order to differentiate from the true stress related to the actual cross-section of the specimen, this stress is frequently called “engineering stress”
3.6.1
stress at yield
σy
stress at the yield strain
Note 1: It is expressed in megapascals (MPa).
Note 2: It may be less than the maximum attainable stress (see Figure 1, curves b and c)
3.6.2
strength
σm
stress at the first local maximum observed during a tensile test
Note 1: It is expressed in megapascals (MPa).
Note 2: This may also be the stress at which the specimen yields or breaks (see Figure 1).
3.6.3
stress at x% strain
σx
stress at which the strain reaches the specified value x expressed as a percentage
Note 1: It is expressed in megapascals (MPa).
Note 2: Stress at x% strain may, for example, be useful if the stress/strain curve does not exhibit a yield point (see Figure 1, curve d).
3.6.4
stress at break
σb
stress at which the specimen breaks
Note 1: It is expressed in megapascals (MPa).
Note 2: It is the highest value of stress on the stress-strain curve directly prior to the separation of the specimen, i.e directly prior to the load drop caused by crack initiation.
3.7
strain
ε
increase in length per unit original length of the gauge.
Note: It is expressed as a dimensionless ratio, or as a percentage (%).
3.7.1
strain at yield yield strain
εy
the first occurrence in a tensile test of strain increase without a stress increase
Note 1: It is expressed as a dimensionless ratio, or as a percentage (%).
Note 2: See Figure 1, curves b and c.
Note 3: See Annex A (informative) for computer-controlled determination of the yield strain.
3.7.2
strain at break
εb
strain at the last recorded data point before the stress is reduced to less than or equal to 10% of the strength if the break occurs prior to yielding
Note 1: It is expressed as a dimensionless ratio, or as a percentage (%).
Note 2: See Figure 1, curves a and d.
3.7.3
strain at strength
εm
strain at which the strength is reached
Note: It is expressed as a dimensionless ratio, or as a percentage (%).
3.8
nominal strain
εt
crosshead displacement divided by the gripping distance
Note 1: It is expressed as a dimensionless ratio, or as a percentage (%).
Note 2: It is used for strains beyond the yield strain (see 3.7.1) or where no extensometers are used.
Note 3: It may be calculated based on the crosshead displacement from the beginning of the test, or based on the increment of crosshead displacement beyond the strain at yield, if the latter is determined with an extensometer (preferred for multipurpose test specimens).
3.8.1
nominal strain at break
εtb
nominal strain at the last recorded data point before the stress is reduced to less than or equal to 10% of the strength if the break occurs after yielding
Note 1: It is expressed as a dimensionless ratio, or as a percentage (%).
Note 2: See Figure 1, curves b and c.
3.9
modulus
Et
slope of the stress/strain curve σ(ε) in the strain interval between ε1 = 0.05% and ε2 = 0.25%
Note 1: It is expressed in megapascals (MPa).
Note 2: It may be calculated either as the chord modulus or as the slope of a linear least-squares regression line in this interval (see Figure 1, curve d).
Note 3: This definition does not apply to films.
3.10
Poisson’s ratio
μ
negative ratio of the strain increment Δεn, in one of the two axes normal to the direction of extension, to the corresponding strain increment Δεl in the direction of extension, within the linear portion of the longitudinal versus normal strain curve
Note: It is expressed as a dimensionless ratio.
3.11
gripping distance
L
initial length of the part of the specimen between the grips
Note: It is expressed in millimeters (mm).
3.12
rigid plastic
plastic that has a modulus of elasticity in flexure (or, if that is not applicable, in tension) greater than 700 MPa under a given set of conditions
3.13
semi-rigid plastic
plastic that has a modulus of elasticity in flexure (or, if that is not applicable, in tension) between 70 MPa and 700 MPa under a given set of conditions
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle and Methods
5 Apparatus
6 Test Specimens
7 Number of Test Specimens
8 Conditioning
9 Procedure
10 Calculation and Expression of Results
11 Precision
12 Test Report
Annex A (Informative) Determination of Strain at Yield
Annex B (Informative) Extensometer Accuracy for the Determination of Poisson’s Ratio
Annex C (Normative) Calibration Requirements for the Determination of the Tensile Modulus
Bibliography
塑料拉伸性能的測定
第1部分：總則
1范圍
GB/T 1040的本部分規定了在規定條件下測定塑料和復合材料拉伸性能的一般原則，并規定了幾種不同形狀的試樣以用于不同類型的材料，這些材料在本標準的其他部分予以詳述。
本方法用于研究試樣的拉伸性能及規定條件下測定拉伸強度，拉伸模量和其他方面的拉伸應力/應變關系。
本方法適用于下列材料：
——硬質和半硬質(見3.12和3.13)熱塑性模塑，擠塑和澆鑄材料，除未填充類型外還包括填充的和增強的混合料，硬質和半硬質熱塑性片材和薄膜；
——硬質和半硬質熱固性模塑材料，包括填充的和增強的復合材料，硬質和半硬質熱固性板材，包括層壓板；
——混入單向或無定向增強材料的纖維增強熱固性和熱塑性復合材料。這些增強材料如氈、織物、無捻粗紗、短切原絲、混雜纖維增強材料、無捻粗紗和碾碎纖維等：預浸漬材料制成的片材(預浸料坯)；
——熱致液晶聚合物。
鑒于ISO 1926.本方法一般不適用于硬質泡沫材料或含微孔材料的夾層結構材料。
2規范性引用文件
下列文件對于本文件的應用是必不可少的。凡是注日期的引用文件，僅注日期的版本適用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改單)適用于本文件。
GB/T 12160—2002 單軸試驗用引伸計的標定( ISO 9513：999，IDT)
GB/T 16825.1—2008靜力單軸試驗機的檢驗第1部分：拉力和(或)壓力試驗機測力系統的檢驗與校準(ISO 7500-1：2004.1DT)
ISO 291 塑料 試樣狀態調節和試驗的標準環境( Plastics- Standard atmospheres for conditioning and testing)
ISO 2602數據的統計處理和解釋 值的估計和置信區間
ISO 16012塑料 試樣的線性尺寸測定(Plastics- Determination of linear dimensions of test specimens)
ISO 20753 塑料 試樣(Plastics - Test specimens)
ISO 23529橡膠物理試驗方法試樣制備和調節通用程序(Rubber-General procedures for pre-paring and conditioning test pieces for physical test methods)
3術語和定義
下列術語和定義適用于本文件。
3.1
標距gauge length。
L0
試樣中間部分兩標線之間的初始距離。
注1：以毫米(mm)為單位。
注2：GB/T 1040不同部分中試樣類型的標距值表示相應的最大標距。
3.2
厚度thickness
h
試樣中間部分矩形截面的較小初始尺寸
注：以毫米(mm)為單位。
3.3
寬度width
b
試樣中間部分矩形截面的較大初始尺寸.
注：以毫米(mm)為單位.
3.4
截面積cross-section
A
試樣初始寬度和厚度的乘積，A=bh。
注：以平方毫米(mm2)為單位。
3.5
試驗速度test speed
v
夾具的分離速度。
注：以毫米每分鐘(mm/ min)為單位。
3.6
拉伸應力tensile stress
σ
在試樣標距內，每單位原始截面積上所受的法向力。
注1：以兆帕(MPa)為單位。
注2：為便于與試樣實際截面積相關的真實應力區分，此應力通常稱作工程應力。
3.6.1
拉伸屈服應力tensile stress at yield
σy
屈服應變時的應力。
注1：以兆帕(MPa)為單位。
注2：該應力值可能小于能達到的最大應力值(參見圖1中的曲線b和曲線c)
3.6.2
拉伸強度tensile strength
σm
在拉伸試驗過程中，觀測到的最大初始應力。
注1：以兆帕( MPa)為單位。
注2：該值也可能見試樣在屈服或斷裂時的應力(參見圖1)。
3.6.3
x%拉伸應變應力tensile stress at x% strain
σx
在應變達到規定值(x %)時的拉伸應力。
注1：以兆帕(MPa)為單位。
注2：可用于應力/應變曲線上無明顯屈服點的情況(參見圖1中的曲線d)。
3.6.4
拉伸斷裂應力tensile stress at break
σb
試樣破壞時的拉伸應力。
注1：以兆帕(MPa)為單位。
注2：試樣斷裂前應力應變曲線上的最大應力值，如斷裂萌生導致的負荷下降前。
3.7
拉伸應變tensile strain
ε
原始標距單位長度的增量。
注：用無量綱的比值或百分數(%)表示。
3.7.1
拉伸屈服應變tensile strain at yield/ tensile yield strain
εy
拉伸試驗中初次出現應力不增加而應變增加時的應變.
注1：用無量綱的比值或百分數(%)表示。
注2：參見圖1中的曲線b和曲線c。
注3：參見附錄A(資料性附錄)計算機控制測定屈服應變。
3.7.2
拉伸斷裂應變tensile strain at break
εb
對斷裂發生在屈服之前的試樣，應力下降至小于或等于強度的10%之前最后記錄的數據點對應的應變。
注1：用無量綱的比值或百分數(%)表示。
注2：參見圖1中的曲線a和曲線d。
3.7.3
拉伸強度拉伸應變tensile strain at tensile strength
εm
拉伸強度對應的應變。
注：用無量綱的比值或百分數(%)表示。
3.8
拉伸標稱應變nominal tensile strain
εt
橫梁位移除以夾持距離。
注1：用無量綱的比值或百分數(%)表示。
注2：適用于屈服點后的應變(見3.7.1)或沒有引伸計使用的情況。
注3：從試驗開始時的橫梁位移來計算。如果見用引伸計(優選多用途試樣來測定應變的，亦可通過屈服點后橫梁位移的增量來計算。
3.8.1
拉伸斷裂標稱應變nominal tensile strain at break
εtb
對斷裂發生在屈服之后的試樣.應力下降至小于或等強度的10%之前最后記錄的數據點對應的標稱應變。
注1：用無量綱的比值或百分數(%)表示。
注2：參見圖1中的曲線b和曲線c。
3.9
拉伸彈性模量modulus of elasticity in tension
Et
模量：應力/應變曲線σ(ε)上應變ε1=0.05%與應變ε2=0.25%區間的斜率。
注1：以兆的(MPa)為單位。
注2：可用弦模量或此區間(參見圖1中的曲線d)線性最小二乘回歸線的斜率來計算。
注3：定義不適用于薄膜。
3.10
泊松比Poisson's ratio
μ
在縱向應變對法向應變關系曲線的起始線性部分內，垂直于拉伸方向上的兩坐標軸之一的拉伸形變量Δεn與拉伸方向上的形變量Δε1之比的負值。
注：用無量綱的比值表示。
3.11
夾具距離gripping distance
L
夾具間試樣部分的初始長度。
注：以毫米(mm)為單位。
3.12
硬質塑料rigid plastic
在規定條件下，彎曲彈性模量或拉伸彈性模量(彎曲彈性模量不適用時)大于700MPa的塑料。
3.13
半硬質塑料semi-rigid plastic
在規定條件下，彎曲彈性模量或拉伸彈性模量(彎曲彈性模量不適用時)在70MPa~700MPa之間的塑料。
圖1典型應力/應變曲線
注：曲線a為脆性材料，其斷裂應變低并且無屈服。曲線d為類似橡膠的柔軟材料。其斷裂應變較大(>50%)。
4原理和方法
4.1原理
沿試樣縱向主軸方向恒速拉伸，直到試樣新裂或其應力(負荷)或應變(伸長)達到某一預定值，測量在這一過程中試驗承受的負荷及其伸長。
4.2 方法
4.2.1這些方法適用于模塑制備的選定的尺寸試樣，或采用機加工、切割或沖裁等方法從成品或半成品上(如模制件、層壓板、薄膜和擠出或澆鑄板)制備的試樣。試樣類型及其制備見關于典型材料的GB/T 1040 的相關部分。某些情況下可使用多用途試樣。多用途和小型試樣見ISO 20753。
4.2.2此方法規定了試樣的優選尺寸。不同尺寸的試樣或不同狀態調節后的試樣試驗結果無可比性。另一些因素，如測試速度和試樣的狀態調節也會影響試驗結果。因此，在進行數據比對時，應嚴格控制這些因素并記錄。
5設備
5.1試驗機
5.1.1概述
試驗機應符合GB/T 16825.1—2008和GB/T 12160—2002 以及本部分5.1.2~5.1.6的規定。
5.1.2試驗速度
試驗機應能達到表1所規定的試驗速度。
表1推薦的試驗速度
速度v(mm/min) 允差/%
0.125 ±20
0.25
0.5
1
2
5
10
20 ±10
50
100
200
300
500
5.1.3夾具
夾具用于夾持試樣與試驗機相連，使試樣的主軸方向與通過夾具中心線的拉力方向重合。試樣應以這種方式夾持以防止被夾試樣相對夾具口滑動。夾具不會引起夾其口處試樣過早破壞或擠壓夾具中的試樣。
例如在拉伸模量的測定中，應變速率的恒定是很重要的，不能由于夾具的移動面改變，特別是在使用楔形夾具時。
注：對于預應力。有必要獲得正確的定位(見9.3)和試樣放置以及避免應力/應變曲線開始階段的趾區。
5.1.4負荷指示裝置
負荷測量系統應符合GB/T 16825.1-2008定義的I級。
5.1.5應變指示裝置
5.1.5.1引伸計
引伸計應符合GB/T 12160-2002規定的1級引伸計的要求，在測量的應變范圍內可獲得此精度。也可用非接觸式引伸計，但要確保其滿足相同的精度要求。
引伸計應可測量試驗過程中任何時刻試樣標距的變化。該儀器最好(但不是必須)能自動記錄這種變化。且在規定的試驗速度下應基本上無慣性滯后。
在精確測定拉伸模量E，時，設備應能以相關值的1%或更優精度測量標距的變化。當使用1A類型試樣時，75mm標距對應的絕對精度為±1.5μm。越小的標距對引伸計的要求越高，見圖2。
注。基于使用的標距，1%的精度要求轉為測定標距內伸長率的不同絕對精度要求。對于小型試樣，由于沒有合適的引伸計，不能獲得更高的精度(見圖2)，
常用光學引伸計記錄就試樣表面發生的形變：單面應變測試方法確保低應變不會受到來自試樣微小的錯位、初始翹曲和在試樣的相對面產生不同應變彎曲的影響。推薦使用平均化試樣相對面應變的測量方法。這與模量測定有關，但不適于較大應變的測量。
5.1.5.2應變計
試樣也可以裝縱向應變計，其精度應為相對值的1%或更優。對于測量模量時，相當于應變精度為20×10-6(20μm應變)。應變計表面處理和粘接劑的選擇應以能顯示被測材料的所有性能為宜。
5.1.6數據的記錄
5.1.6.1概述
所需記錄數據(負荷、應變、伸長率)的數據采集頻率須足夠高以滿足要求的精度。
5.1.6.2應變數據的記錄
應變數據記錄的數據采集頻率基于
——試驗速度v，以mm/min為單位；
——標距和初始夾具距離的比值，L0/L；
——獲得準確數據應變信號的最小分辨率r，以mm為單位。一般為精度的一半或更優。從傳感器到指示器的整體傳輸的最小數據采集頻率fmin，以Hz為單位，計算如下：
(1)
試驗機的采樣頻率應至少與最小數據采集頻率fmin相同。
5.1.6.3負荷數據的記錄
要求的采樣頻率基于試驗速度、應變范圍、精度和夾具距離。模量、試驗速度和夾具距離決定負荷增長率。負荷增長率與所需精度的比值決定采樣頻率。見下示例。
式(2)給出負荷增長率：
(2)
式中：
E——彈性模量，單位為兆帕(MPa)；
A——試樣截面積，單位為平方毫米(mm2)；
V——試驗速度，單位為毫米每分(mm/min)；
L——夾具距離，單位為毫米(mm)。
假定相關負荷的測量精度在1%以內，對引伸計而言，在模量范圍內，同樣以負荷的差值與其精度要求的比值來確定數據采集頻率，則可使用如下方程：
ΔF=E·A·(ε2-ε1)=E·A·Δε (3)
精度(1%的一半)：
r=5×10-3×ΔF=5×10-3×E·A·Δε (4)
采樣頻率：
(5)
示例：v=1mm/min，Δε=2×10-3，L=115mm，則采樣頻率fforce=14.5Hz。
L0=75mm的增量ΔL
L0=50mm的增量ΔL
L0=25mm的增量ΔL
L0=20mm的增量ΔL
圖2假定精度為1%，不同標距時模量測定的引伸計精度要求
5.2試樣寬度和厚度測量設備
如適用見ISO 16012和ISO 23529。
6試樣
6.1形狀和尺寸
見本部分與受試材料有關的部分。
6.2試樣制備
見本部分與受試材料有關的部分。
6.3標線
見本部分與標距長度條件有關的部分。
如果使用光學引伸計特別是對于薄片和薄膜，應在試樣上標出規定的標線，標線與試樣的中點距離應相等(±1 mm)，兩標線間距離的測量精度應達到1%或更優。
標線不能刻劃、沖刻或壓印在試樣上，以免損壞受試材料，應采用對受試材料無影響的標線，而且所劃的相互平行的每條標線要盡量窄。
6.4試樣的檢查
試樣應無扭曲，相鄰的平面間應相互垂直(見下注)。表面和邊緣應無劃痕、空洞、凹陷和毛刺。
為使試樣符合這些要求，應把其緊貼在直尺、三角尺或平板上，用目視觀測或用測數卡尺對試樣進行測量檢查。
使用尺寸和方向如尖端/刀刃的測量規以便精確測定所需位置的尺寸。
經發現試樣有一項或幾項不符合要求時應舍棄。對不符合要求的試樣進行測試時應說明原因。
注塑試樣需要1°~2°的拔模角以方便脫模。此外，注塑試樣不可能無凹痕。由于冷卻過程的不同，試樣中間厚度值一般比邊緣小。可接受厚度差異為Δh≤0.1 mm(見圖3)。
