標準編號:	GB/T 229-2020
中文名稱:	金屬材料 夏比擺錘沖擊試驗方法
英文名稱:	Metallic materials—Charpy pendulum impact test method
中標分類:	H22    金屬力學性能試驗方法
行業分類:	GB    國家標準
ICS分類:	77.040.10 77.040.10    金屬材料力學試驗 77.040.10
發布機構:	國家市場監督管理總局 國家標準化管理委員會
發布日期:	2020-09-29
實施日期:	2021-4-1
標準狀態:	valid
替代舊標準:	GB/T 229-2007 金屬材料 夏比擺錘沖擊試驗方法
翻譯語言:	英文
文件格式:	PDF
中文字符數:	27000 字
翻譯價格(元):	1800.0
交付時間:	付款后 1 個工作日

This standard is developed in accordance with the rules given in GB/T 1.1-2009. This standard replaces GB/T 229-2007 Metallic materials - Charpy pendulum impact test method, and the following main technical changes have been made with respect to GB/T 229-2007: - notch-free test pieces are added in the scope, and requirements are made for terms and definitions, symbols and interpretation, dimensional deviation and test piece installation (see Clause 1, 3.2.1, Table 1, Table 2, 8.1 and Annex A); - some of the terms and definitions are modified and added (see 3.1.3, 3.2.1, 3.2.2 of this standard, and 3.2.1 and 3.2.2 of 2007 edition); - symbol B of sample thickness, angle symbol α when pendulum is released, explanation of angles of rise β1 and β2, symbol KN of nominal initial potential energy, symbol M of torque, symbol ρ of energy loss caused by pointer friction, symbol ρ' of energy loss caused by bearing friction and air resistance, and correction symbol ρβ of energy loss caused by angle of rise β are added, and symbol of shear fracture appearance is changed to SFA. The symbol of transition temperature symbol Tt27 corresponding to the specified absorbed energy value of 27 J, transition temperature symbol Tt50% us corresponding to 50% absorbed energy of the upper shelf, transition temperature symbol Tt50%SFA corresponding to 50% shear fracture and transition temperature symbol Tt0.9 corresponding to lateral expansion 0.9 mm are added (see table 1 of this standard, and that of 2007 edition); - the principle of impact test is added (see Clause 5 of this standard and Clause 5 of 2007 edition); - the determination of friction loss is added (see 8.2); - the requirements of test temperature are added (see 8.3.3 of this standard, and 8.2.3 of 2007 edition); - mandatory information and optional information are added in the test report [see 9.1 g), 9.2 j) and k)]; - informative Annex E “Measurement uncertainty of an absorbed energy value, K” (see Annex E) is added; - the informative Annex about high temperature or low temperature compensation value is deleted (see Annex E of 2007 edition). This standard has been redrafted and modified in relation to IEC 148-1:2016 Metallic materials - Charpy pendulum impact test - Part 1: Test method Compared with ISO 148-1: 2016, there are structural differences in this standard, with 8.9 test results added. There are some technical differences between this standard and ISO 148-1:2016, which are marked with perpendicular single line (｜) in the outside page margin of the provisions concerned. The technical differences and their causes are as follows: —— In Clause 1, notch-free test pieces are added to adapt to China's national conditions; ——the adjustments of technical differences are made for the normative references in this standard so as to adapt to the technical conditions of China. The adjustments are mainly reflected in Clause 2 "Normative references", which are shown in the following: ? ISO 148-2 is replaced by GB/T 3808, which is modified in relation to the international standard (see 7.2 and E.2.1.2); ? GB/T 2975 is added for reference (see 6.4); ? GB/T 8170 is added for reference (see 8.9); ? JJG 145 is added for reference (see 7.2); ? ISO 268-1 is deleted (see Table 2 of ISO 148 -1). - The symbol KT and its interpretation missing in ISO standard are added in Table 1, and the symbol and interpretation of notch-free test pieces are correspondingly as notch-free test pieces are added in the scope. The unit of β1 and β2 is defined as "°", and the unit of K1, K2 and KN is defined as "J" to avoid confusion. - the last two paragraphs of Clause 5 are changed to notes, because they further explain the principle; - “And test pieces with other thicknesses may also be used upon agreement.” is added in 6.1.2 to expand the applicable scope of this standard; ? - “The samples shall be cut according to relevant product standards or GB/T 2975.” is added in 6.4 to facilitate practical operation; - in Table 2, the dimensions and tolerances of U-notch test piece with ligament width of 8 mm are added, the notes of notch-free test pieces were added, the included angle tolerance between adjacent longitudinal faces of test pieces is adjusted, and the tolerance grades of two kinds of notches are deleted to meet the national conditions of China; - for the convenience of application, the symbols KW2 and KW8 for the striking edge of the notch-free test piece pendulum are added in 7.3; - for the convenience of operation of notch-free test pieces, the provisions on the installation position of notch-free test pieces and the inspection before the test are added in 8.1; - the detailed requirements on bearing friction and wind resistance loss are added in 8.2.2 for the implementation of this standard; - the requirements of the lower limit of use and resolution of the testing machine are added in 8.5, and Note 2 is added to explain, so as to increase the operability of the standard and facilitate the implementation of this standard; - the explanation “If the pendulum does not break the sample, and the measured absorbed energy exceeds the energy range of the testing machine due to insufficient impact energy of the testing machine” is added in 8.6 to increase the operability of this standard. - the rounding off requirements of absorbed energy is added in 8.9, and increase the operability of this standard; - c) notch type and ligament width (notch depth) is added in 9.1, and the requirements of sample size expression are added in d) to increase the operability of this standard; - in Annex A, the sentence "self-centring tongs with thickness of 5 mm and 3 mm” are deleted due to data error; and the requirements of tongs for notch-free test pieces and U-notch tongs are added to increase the operability of this standard and facilitate the implementation of this standard. The following editorial changes have been made in this standard: - the standard name is changed; - the expression "the letter W is used to indicate notch-free test piece" is added in the note of 3.1.2. This standard was proposed by China Iron and Steel Association. This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China. The previous editions of standard replaced by this standard are as follows: ——GB/T 229-1984, GB/T 229-1994, GB/T 229-2007. Metallic materials - Charpy pendulum impact test method 1 Scope This standard specifies the Charpy (V-notch and U-notch) pendulum impact test method for determining the energy absorbed in an impact test of metallic materials. This standard is applicable to Charpy pendulum impact test at room temperature, high temperature or low temperature, but does not cover instrumented impact testing, which is specified in GB/T 19748. 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 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing (GB/T 2975-2018, ISO 377:2017, MOD) GB/T 3808 Verification of pendulum-type impact testing machines (GB/T 3808-2018, ISO 148-2: 2008, MOD) GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values JJG 145 Verification regulation of pendulum impact testing machines 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 Definitions pertaining to energy 3.1.1 initial potential energy potential energy Kp potential energy of the pendulum hammer prior to its release for the impact test, as determined by direct verification 3.1.2 absorb energy K energy required to break a test piece with a pendulum impact testing machine, after correction for friction Note: The letter V or U is used to indicate the notch geometry, the letter W is used to indicate notch-free test piece. The number 2 or 8 is used as a subscript to indicate the radius of the striker, for example KV2. 3.1.3 nominal initial potential energy nominal energy KN energy assigned by the manufacturer of the pendulum impact testing machine 3.2 Definitions pertaining to test piece 3.2.1 width W distance between the notched face and the opposite face Note 1: For notch-free test piece, it is the distance between the surface where the strike center is located and its opposite surface. Note 2: See Figure 1. Note 3: In GB/T 229-2007, the distance between the notched face and the opposite face was specified as “height”. Changing this dimension to “width” makes this standard consistent with the terminology used in other fracture standards. 3.2.2 thickness B dimension perpendicular to the width and parallel to the notch Note 1: For notch-free test piece, it is the minimum dimension perpendicular to the width direction. Note 2: See Figure 1. Note 3: In GB/T 229-2007, the dimension perpendicular to the width direction and parallel to the notch axis was specified as “width”. Changing this dimension to “thickness” makes this standard consistent with the terminology used in other fracture standards. 3.2.3 length L largest dimension perpendicular to the notch Note 1: For notch-free test piece, it is the maximum dimension perpendicular to the width direction. Note 2: The notch direction is the notch depth direction, as shown in Figure 1. Key 1——anvil; 4——shroud; 7——thickness of test piece, B; 2——standardized test piece; 5——width of test piece, W; 8——centre of strike; 3——test piece supports; 6——length of test piece, L; 9——direction of pendulum swing. Note: The shroud may be used in U-shaped pendulum testing machine to protect the broken test piece from rebounding to the pendulum and jamming. Figure 1 Relative position of test piece to the supports and anvils of a pendulum impact testing machine 4 Symbols and interpretations The symbols and interpretations applicable to this standard are indicated in Table 1. ? Table 1 Symbols, designation and unit Symbol Unit Designation B mm thickness of test piece α ° angle of fall of the pendulum β1 angle of rise in the fall of the pendulum without a test piece in position β2 angle of rise in the fall of the pendulum without a test piece in position and without resetting the indication mechanism L mm length of test piece LE mm lateral expansion K J absorbed energy (expressed as KV2, KV8, KU2, KU8, to identify specific notch geometries and the radius of the striking edge) J indicated absorbed energy in the fall of the pendulum without a test piece in position K2 J indicated absorbed energy in the fall of the pendulum without a test piece in position and without resetting the indication mechanism KN J nominal initial potential energy Kp J initial potential energy (potential energy) KT J total absorbed energy KV2 J absorbed energy for a V-notch test piece using a 2 mm striker KV8 J absorbed energy for a V-notch test piece using a 8 mm striker KU2 J absorbed energy for a U-notch test piece using a 2 mm striker KU8 J absorbed energy for a U-notch test piece using a 8mm striker KW2 J absorbed energy for a notch-free test piece using a 2 mm striker KW8 J absorbed energy for a notch-free test piece using a 8mm striker M N·m moment equal to the product F·l2 ρ J absorbed energy loss caused by pointer friction ρ′ J absorbed energy loss caused by bearing friction and air resistance ρβ J correction of absorbed energy losses for an angle of rise β SFA % shear fracture appearance Tt ℃ transition temperature W mm width of test piece Tt27 ℃ transition temperature defined at a specific value of absorbed energy; for example, 27 J Tt50%US ℃ transition temperature defined at a particular percentage of the absorbed energy of the upper shelf; for example, 50 % Tt50%SFA ℃ transition temperature defined at a particular proportion of shear fracture; for example, 50 % Tt0.9 ℃ transition temperature defined at a particular amount of lateral expansion; for example, 0.9 mm ? 5 Principles of the test This test consists of breaking a test piece with a single blow from a swinging pendulum, under the conditions defined in Clauses 6, 7 and 8. The notch in the test piece has a specified geometry and is located in the middle between two supports, opposite to the location which is impacted in the test. The energy absorbed in the impact test, the lateral expansion and the shear fracture appearance are normally determined. Because the impact values of many materials vary with temperature, tests shall be carried out at a specified temperature. When this temperature is other than ambient, the test piece shall be heated or cooled to that temperature, under controlled conditions. Note 1: The Charpy pendulum impact test is often used in routine, high-throughput pass/fail acceptance tests in industrial settings. For these tests, it may not be important whether the test sample is completely broken, partially broken, or simply plastically deformed and dragged through the anvils. In theoretical research, the measured energy values shall be studied in more detail, in which case it can be highly relevant whether the sample is broken or not. Note 2: It is important to note that not all Charpy pendulum impact test results can be directly compared. For example, the test can be performed with hammers having strikers with different radii, or with different test piece shapes. Tests performed with different strikers can give different results.[2] This is why not only the adherence to this standard but also a clear and complete reporting of the type of instrument, the test piece and the details of the post-test test pieces are crucial for comparability of results.

Foreword I 1 Scope 2 Normative references 3 Terms and definitions 3.1 Definitions pertaining to energy 3.2 Definitions pertaining to test piece 4 Symbols and interpretations 5 Principles of the test 6 Test pieces 6.1 General 6.2 Notch geometry 6.3 Tolerance of the test pieces 6.4 Preparation of the test pieces 6.5 Marking of the test pieces 7 Test equipment 7.1 General 7.2 Installation and verification 7.3 Striker 8 Test procedure 8.1 General 8.2 Friction measurement 8.3 Test temperature 8.4 Specimen transfer 8.5 Machine capacity 8.6 Incomplete fracture 8.7 Test piece jamming 8.8 Post-fracture inspection 8.9 Test result 9 Test report 9.1 Mandatory information 9.2 Optional information Annex A (Informative) Self-centring tongs Annex B (informative) Lateral expansion Annex C (Informative) Fracture appearance Annex D (Informative) Absorbed energy vs. temperature curve and the transition temperature Annex E (Informative) Measurement uncertainty of an absorbed energy value, K Bibliography

金屬材料 夏比擺錘沖擊試驗方法 1 范圍 本標準規定了金屬材料在沖擊試驗中測定沖擊試樣(V型、U型缺口和無缺口試樣)吸收能量的夏比擺錘沖擊試驗方法。 本標準適用于室溫、高溫或低溫條件下夏比擺錘沖擊試驗，但不包括儀器化沖擊試驗方法，這部分內容參見GB／T 19748。 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 2975 鋼及鋼產品 力學性能試驗取樣位置及試樣制備(GB／T 2975—2018，ISO 377：2017，MOD) GB／T 3808 擺錘式沖擊試驗機的檢驗(GB／T 3808—2018，ISO 148-2：2008，MOD) GB／T 8170 數值修約規則與極限數值的表示和判定 JJG 145 擺錘式沖擊試驗機檢定規程 3 術語和定義 下列術語和定義適用于本文件。 3．1 能量相關定義 3．1．1 初始勢能 initial potential energy 勢能 potential energy Kp 在落擺進行沖擊試驗前擺錘的勢能，由直接校準確定。 3．1．2 吸收能量 absorbed energy K 采用擺錘沖擊試驗機使試樣發生斷裂需要的能量，該能量是進行摩擦修正后的值。 注：用字母V或U表示缺口幾何形狀，用字母W代表無缺口試樣，用下標數字2或8表示擺錘錘刃半徑，例如KV2。 3．1．3 初始勢能標稱值 nominal initial potential energy 能量標稱值 nominal energy KN 由沖擊試驗機制造商給定的名義能量值。 3．2 試樣相關定義 3．2．1 寬度 width W 開缺口面與其相對面之間的距離。 注1：對于無缺口試樣為打擊中心所在面與其相對面之間的距離。 注2：見圖1。 注3：在GB／T 229—2007中開缺口面與其相對面之間的距離定義為“高度”，替換為“寬度”是為了與其他原理相同的斷裂標準保持一致。 3．2．2 厚度 thickness B 垂直于寬度方向且與缺口軸線平行的尺寸。 注1：對于無缺口試樣為與寬度方向垂直的最小尺寸。 注2：見圖1。 注3：在GB／T 229—2007中垂直于寬度方向且與缺口軸線平行的尺寸定義為“寬度”，替換為“厚度”是為了與其他原理相同的斷裂標準保持一致。 3．2．3 長度 length L 與缺口方向垂直的最大尺寸。 注1：對于無缺口試樣為與寬度方向垂直的最大尺寸。 注2：缺口方向即缺口深度方向，見圖1。 說明： 1——砧座； 4——保護罩； 7——試樣厚度，B； 2——標準尺寸試樣； 5——試樣寬度，W； 8——打擊點； 3——試樣支座； 6——試樣長度，L； 9——擺錘沖擊方向。 注：保護罩可用于U型擺錘試驗機，用于保護斷裂試樣不回彈到擺錘和造成卡錘。 圖1 試樣與擺錘沖擊試驗機支座及砧座相對位置示意圖 4 符號和說明 本文件使用符號和說明見表1。 表1 符號、名稱及單位 符號 單位 名稱 B mm 試樣厚度 α ° 擺錘釋放時的角度 β1 不安裝試樣時擺錘下落的升角 β2 不安裝試樣且不復位指針時擺錘下落的升角 L mm 試樣長度 LE mm 側膨脹值 K J 吸收能量(以KV2、KV8、KU2、KU8表示不同的缺口幾何形狀和不同錘刃半徑) K1 J 不安裝試樣時擺錘下落的指示吸收能量 K2 J 不安裝試樣且不復位指針時擺錘下落的指示吸收能量 KN J 初始勢能標稱值 Kp J 初始勢能(勢能) KT J 總吸收能量 KV2 J V型缺口試樣使用2 mm擺錘錘刃測得的沖擊吸收能量 KV8 J V型缺口試樣使用8 mm擺錘錘刃測得的沖擊吸收能量 KU2 J U型缺口試樣使用2 mm擺錘錘刃測得的沖擊吸收能量 KU8 J U型缺口試樣使用8 mm擺錘錘刃測得的沖擊吸收能量 KW2 J 無缺口試樣使用2 mm擺錘錘刃測得的沖擊吸收能量 KW8 J 無缺口試樣使用8 mm擺錘錘刃測得的沖擊吸收能量 M N·m 擺錘力矩，等于F·l2 ρ J 由指針摩擦帶來的能量損耗 ρ′ J 由軸承摩擦和空氣阻力帶來的能量損耗 ρβ J 仰角β對應的修正能量損耗 SFA ％ 剪切斷面率 Tt ℃ 轉變溫度 W mm 試樣寬度 Tt27 ℃ 由指定吸收能量值(例如27 J)確定的轉變溫度 Tt50％US ℃ 由指定吸收能量上平臺的百分數(例如50％)確定的轉變溫度 Tt50％SFA ℃ 由指定剪切斷面率(例如50％)確定的轉變溫度 Tt0.9 ℃ 由指定側膨脹值(例如0.9 mm)確定的轉變溫度 5 試驗原理 本標準規定的試驗采用擺錘單次沖擊的方式使試樣破斷，試驗條件由第6章、第7章和第8章給出。試樣的缺口有規定的幾何形狀并位于兩支座的中心、打擊中心的對面。測定參數包括吸收能量、側膨脹值和剪切斷面率等。由于很多材料的沖擊結果會隨溫度變化而變化，試驗應在給定溫度條件下進行，當給定溫度不是室溫時，試樣應在可控溫度下進行加熱或冷卻。 注1：夏比擺錘沖擊試驗是工業應用方面常用的驗收判定試驗，對于這類試驗，試樣完全斷裂、部分斷裂或者只是發生塑性變形并劃過砧座，這些情況并不重要。在理論研究方面，需對測定的能量值進行深入研究，測定的能量值可能與試樣是否破斷有很大關系。 注2：需要注意不是所有的夏比沖擊試驗結果都可以直接進行比較。例如，試驗采用的擺錘錘刃半徑可能不同，或采用不同形狀的試樣。采用不同擺錘錘刃可能導致試驗結果產生差異[2]。這也是完整的試驗報告除了執行標準還需包括明確的試驗機類型、試樣類型、試驗后試樣斷裂情況等用于決定試驗結果可比較性項目的原因。 6 試樣 6．1 一般要求 6．1．1 標準尺寸沖擊試樣長度為55 mm，橫截面為10 mm×10 mm方形截面。在試樣長度的中間位置有V型或U型缺口，見6．2．1和6．2．2。 6．1．2 如試料不夠制備標準尺寸試樣，如無特殊規定，可使用厚度為7.5 mm、5 mm或2.5 mm的小尺寸試樣(見圖2和表2)，通過協議也可使用其他厚度的試樣。 注1：只有采用形狀和尺寸均相同的試樣才可以對結果進行直接比較。 注2：對于低能量的沖擊試驗，用墊片使小尺寸試樣位于擺錘中心位置以避免額外的能量吸收非常重要。對于高能量的沖擊試驗采用墊片的重要性會有所降低。墊片可以置于支座上方或者下方，使試樣厚度的中心位置位于10 mm支座以上5 mm的位置(即標準試樣的打擊中心位置)。 6．1．3 對于需要進行熱處理的試驗材料，應在最終熱處理后的試料上進行精加工和開缺口，除非可以證明在熱處理前加工試樣不會影響試驗結果。 6．2 缺口幾何形狀 6．2．1 應仔細制備試樣缺口，以保證缺口根部半徑沒有影響吸收能量的加工痕跡。缺口對稱面應垂直于試樣縱向軸線(見圖2)。 6．2．2 V型缺口夾角應為45°，根部半徑為0.25 mm[見圖2a)和表2]，韌帶寬度為8 mm(缺口深度為2 mm)。 6．2．3 U型缺口根部半徑為1 mm[見圖2b)和表2]，韌帶寬度為8 mm或5 mm(缺口深度為2 mm或5 mm，除非另有規定)。 6．3 試樣尺寸的偏差 指定試樣和缺口的尺寸偏差見圖2和表2。 a) V型缺口 b) U型缺口 注：符號L、W、B和數字1～5的尺寸見表2。 圖2 夏比擺錘沖擊試樣 表2 試樣的尺寸與偏差 名稱 符號或 序號 V型缺口試樣a U型缺口試樣 名義尺寸 機加工公差 名義尺寸 機加工公差 試樣長度 L 55 mm ±0.60 mm 55 mm ±0.60 mm 試樣寬度 W 10 mm ±0.075 mm 10 mm ±0.11 mm 試樣厚度標準尺寸試樣 10 mm ±0.11 mm 10 mm ±0.11 mm 試樣厚度小尺寸試樣b B 7.5 mm ±0.11 mm 7.5 mm ±0.11 mm 5 mm ±0.06 mm 5 mm ±0.06 mm 2.5 mm ±0.05 mm — — 缺口角度 1 45° ±2° — — 韌帶寬度 2 8 mm ±0.075 mm 8 mm ±0.09 mm — — 5 mm ±0.09 mm 缺口根部半徑 3 0.25 mm ±0.025 mm 1 mm ±0.07 mm 缺口對稱面端部距離 4 27.5 mm ±0.42 mmc 27.5 mm ±0.42 mmc 缺口對稱面試樣縱軸角度 90° ±2° 90° ±2° 試樣相鄰縱向面間夾角 5 90° ±1° 90° ±1° 表面粗糙度d Ra ＜5 μm — ＜5 μm — a 對于無缺口試樣，要求與V型缺口試樣相同(缺口要求除外)。 b 如指定其他厚度(如2 mm或3 mm)，應規定相應的公差。 c 對端部對中自動定位試樣的試驗機，建議偏差采用±0.165 mm代替±0.42 mm。 d 試樣的表面粗糙度Ra應優于5 μm，端部除外。 6．4 試樣的制備 試樣樣坯的切取應按相關產品標準或GB／T 2975的規定執行，試樣制備過程應使任何可能令材料發生改變(例如加熱或冷作硬化)的影響減至最小。 6．5 試樣的標記 試樣標記可以標在不與支座、砧座及擺錘錘刃接觸的試樣表面上。由試樣標記導致的塑性變形和表面不連續性不應對吸收能量產生影響(見8．8)。 7 試驗設備 7．1 一般要求 所有測量儀器均應溯源至國家或國際基準。測量儀器應在合適的周期內進行校準。 7．2 安裝及校準 試驗機應按照GB／T 3808或JJG 145的要求進行安裝及校準。 7．3 擺錘錘刃 擺錘錘刃邊緣曲率半徑應為2 mm或8 mm兩者之一。用符號的下標數字表示：KV2、KV8、KU2、KU8、KW2、KW8。擺錘錘刃半徑的選擇應依據相關產品標準的規定。 注：采用2 mm和8 mm擺錘錘刃得到的試驗結果可能有差異。 8 試驗程序 8．1 一般要求 8．1．1 試樣應緊貼試驗機砧座，試樣缺口對稱面與兩砧座中間平面間的距離應不大于0.5 mm。錘刃打擊中心位于缺口對稱面、試樣缺口的對面(見圖1)，對于無缺口試樣應使錘刃打擊中心位于試樣長度方向和厚度方向的中間位置。 8．1．2 試驗前應檢查砧座跨距，砧座跨距應保證在40＋0.20 mm以內；并檢查砧座網角和擺錘錘刃部位是否有損傷或外來金屬粘連，如發現存在問題應對問題部件及時調整、修磨或更換以保證試驗結果的準確可靠。 8．2 摩擦損耗的測定 8．2．1 每天開始進行沖擊試驗前應對摩擦造成的能量損耗進行檢查。可以按下述方法進行摩擦損耗的評估，也可采用其他方法。 注：摩擦的能量損耗包括但不限于空氣阻力、軸承摩擦和指針摩擦。試驗機摩擦的增加會影響吸收能量的測量。