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ASTM C1940

來(lái)源:泰然健康網(wǎng) 時(shí)間:2024年11月23日 10:01

1.1 本試驗(yàn)方法描述了測(cè)定連續(xù)纖維增強(qiáng)陶瓷基復(fù)合材料(CMC)臨界模式I層間應(yīng)變能釋放率的實(shí)驗(yàn)方法和程序,具體如下 G Ic 該特性有時(shí)也被描述為I型斷裂韌性或I型斷裂阻力。 1.2 該試驗(yàn)方法主要適用于具有二維層壓板結(jié)構(gòu)的陶瓷基復(fù)合材料,該結(jié)構(gòu)由在脆性陶瓷基體內(nèi)的單向帶或二維編織織物結(jié)構(gòu)中的連續(xù)陶瓷纖維的疊層組成。 1.3 該試驗(yàn)方法確定了在兩個(gè)薄層或?qū)又g的層間界面處分層生長(zhǎng)時(shí)產(chǎn)生的每單位新表面積釋放的彈性應(yīng)變能。在本試驗(yàn)方法中,術(shù)語(yǔ)分層專(zhuān)門(mén)指代這種類(lèi)型的生長(zhǎng),而術(shù)語(yǔ)裂紋是一個(gè)更通用的術(shù)語(yǔ),也可以指代基體開(kāi)裂、層內(nèi)分層生長(zhǎng)或纖維斷裂。 1.4 該試驗(yàn)方法使用雙懸臂梁(DCB)試樣來(lái)確定臨界模式I層間應(yīng)變能量釋放率( G Ic ).根據(jù)測(cè)試方法,聚合物基復(fù)合材料(PMCs)的DCB測(cè)試方法已標(biāo)準(zhǔn)化 D5528 該試驗(yàn)方法采用了類(lèi)似的程序,但進(jìn)行了修改,以說(shuō)明CMC與PMCs相比的不同物理性能、鋼筋結(jié)構(gòu)、應(yīng)力-應(yīng)變響應(yīng)和失效機(jī)制。 1.5 本測(cè)試適用于環(huán)境溫度和大氣測(cè)試條件,但該測(cè)試方法也可用于高溫或環(huán)境暴露測(cè)試,使用適當(dāng)?shù)沫h(huán)境測(cè)試箱、用于控制和測(cè)量測(cè)試箱溫度、濕度和大氣的測(cè)量設(shè)備、高溫夾具、,以及用于測(cè)量分層生長(zhǎng)的改良設(shè)備。 1.6 以國(guó)際單位制表示的數(shù)值應(yīng)視為標(biāo)準(zhǔn)。本標(biāo)準(zhǔn)不包括其他計(jì)量單位。 1.6.1 本試驗(yàn)方法中表達(dá)的數(shù)值符合國(guó)際單位制(SI)和 IEEE/ASTM SI 10 . 1.7 本標(biāo)準(zhǔn)并不旨在解決與其使用相關(guān)的所有安全問(wèn)題(如有)。本標(biāo)準(zhǔn)的使用者有責(zé)任在使用前制定適當(dāng)?shù)陌踩?、健康和環(huán)境實(shí)踐,并確定監(jiān)管限制的適用性。 具體危害說(shuō)明見(jiàn)第節(jié) 8. . 1.8 本國(guó)際標(biāo)準(zhǔn)是根據(jù)世界貿(mào)易組織技術(shù)性貿(mào)易壁壘委員會(huì)發(fā)布的《關(guān)于制定國(guó)際標(biāo)準(zhǔn)、指南和建議的原則的決定》中確立的國(guó)際公認(rèn)的標(biāo)準(zhǔn)化原則制定的。 ====意義和用途====== 5.1 層間分層生長(zhǎng)可能是層合CMC結(jié)構(gòu)中的一種關(guān)鍵失效模式。了解層合CMC的層間分層生長(zhǎng)阻力對(duì)于材料開(kāi)發(fā)和選擇以及CMC部件設(shè)計(jì)至關(guān)重要。 (請(qǐng)參閱 ( 1- 8. ) 3. 哪些給出 G Ic 值為20?J/m 2. 至800?J/m 2. 適用于環(huán)境溫度下的不同CMC和碳-碳復(fù)合材料系統(tǒng)。) 5.2 進(jìn)行此測(cè)試會(huì)產(chǎn)生多個(gè)值 G Ic 其傳統(tǒng)上相對(duì)于測(cè)量該值時(shí)的分層長(zhǎng)度繪制(參見(jiàn) 圖2 ).對(duì)測(cè)試請(qǐng)求者有價(jià)值的特定數(shù)據(jù)將取決于激發(fā)測(cè)試的最終用途。 5.2.1 從預(yù)植入插入物或機(jī)加工切口開(kāi)始的第一次生長(zhǎng)增量有時(shí)被描述為非預(yù)裂紋(NPC)韌性。NPC韌性可能令人感興趣,因?yàn)樗梢源碇圃旎蚣庸と毕?,如層壓板中的異物碎屑或加工過(guò)程中的錯(cuò)誤。 5.2.2 假設(shè)在第一次增量之后出現(xiàn)的尖銳裂紋尖端開(kāi)始的下一次增長(zhǎng)增量有時(shí)被定義為預(yù)裂紋(PC)韌性。PC韌性可能令人感興趣,因?yàn)樗艽韺?duì)自然發(fā)生或損傷引起的分層生長(zhǎng)的抵抗力。 5.2.3 剩余的增長(zhǎng)增量共同形成R曲線,提供了如何 G Ic 隨著分層的進(jìn)展而演變。在單向帶層壓板中,由于嵌套纖維在分層平面上的橋接,R曲線通常會(huì)增加,人為地增加 G Ic 對(duì)于幾乎沒(méi)有層間嵌套的2-D編織層壓板,R曲線可以是平坦的。 5.2.4 R曲線平坦的增長(zhǎng)增量,以及 G Ic 已達(dá)到穩(wěn)定狀態(tài)值,定義為 G IR ,可能是感興趣的,并且也可能在設(shè)計(jì)和分析中有用。 5.3 此測(cè)試方法用于測(cè)量 G Ic CMC材料的用途如下: 5.3.1 定量確定CMC材料變量(纖維界面涂層、基體結(jié)構(gòu)和孔隙率、纖維結(jié)構(gòu)、加工和環(huán)境變量、調(diào)理/暴露處理等)的影響。 )在 G Ic 以及特定CMC材料的層間裂紋擴(kuò)展和損傷機(jī)制; 5.3.2 要確定CMC材料是否顯示R曲線行為,其中 G Ic 隨著裂紋擴(kuò)展而變化,或者在給定的分層生長(zhǎng)量下達(dá)到穩(wěn)定值。 圖2 顯示了SiC-SiC復(fù)合材料的R曲線行為 ( 1. ) ; 5.3.3 為CMC損傷容限、耐久性或可靠性分析和壽命預(yù)測(cè)制定分層失效標(biāo)準(zhǔn)和設(shè)計(jì)容許值; 注3: 只有在確信測(cè)試產(chǎn)生的是材料特性而不是結(jié)構(gòu)幾何形狀的情況下,才能可靠地將測(cè)試數(shù)據(jù)用于此目的- 依賴,財(cái)產(chǎn)。 5.3.4 定量比較的相對(duì)值 G Ic 對(duì)于具有不同成分和材料性能、增強(qiáng)結(jié)構(gòu)、加工參數(shù)或環(huán)境暴露條件的不同CMC材料;和 5.3.5 定量比較的值 G Ic 從不同批次的特定CMC材料中獲得,以進(jìn)行批次驗(yàn)收質(zhì)量控制,用作材料篩選標(biāo)準(zhǔn),或評(píng)估批次變異性。

1.1 This test method describes the experimental methods and procedures for the determination of the critical mode I interlaminar strain energy release rate of continuous fiber- reinforced ceramic matrix composite (CMC) materials in terms of G Ic . This property is also sometimes described as the mode I fracture toughness or the mode I fracture resistance. 1.2 This test method applies primarily to ceramic matrix composite materials with a 2-D laminate structure, consisting of lay-ups of continuous ceramic fibers, in unidirectional tape or 2-D woven fabric architectures, within a brittle ceramic matrix. 1.3 This test method determines the elastic strain energy released per unit of new surface area created as a delamination grows at the interlaminar interface between two lamina or plies. The term delamination is used in this test method to specifically refer to this type of growth, while the term crack is a more general term that can also refer to matrix cracking, intralaminar delamination growth, or fiber fracture. 1.4 This test method uses a double cantilever beam (DCB) specimen to determine the critical mode I interlaminar strain energy release rate ( G Ic ). A DCB test method has been standardized for polymer matrix composites (PMCs) under Test Method D5528 . This test method addresses a similar procedure, but with modifications to account for the different physical properties, reinforcement architectures, stress-strain response, and failure mechanisms of CMCs compared to PMCs. 1.5 This test is written for ambient temperature and atmospheric test conditions, but the test method can also be used for elevated temperature or environmental exposure testing with the use of an appropriate environmental test chamber, measurement equipment for controlling and measuring the chamber temperature, humidity, and atmosphere, high temperature gripping fixtures, and modified equipment for measuring delamination growth. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6.1 Values expressed in this test method are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10 . 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8 . 1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Interlaminar delamination growth can be a critical failure mode in laminated CMC structures. Knowledge of the resistance to interlaminar delamination growth of a laminated CMC is essential for material development and selection, and for CMC component design. (See ( 1- 8 ) 3 which give G Ic values of 20?J/m 2 to 800?J/m 2 for different CMC and carbon-carbon composite systems at ambient temperatures.) 5.2 Conducting this test produces multiple values of G Ic which are traditionally plotted against the delamination length at which that value was measured (see Fig. 2 ). The specific data of value to the test requestor will depend on the end use that motivated testing. 5.2.1 The first increment of growth, initiated from a pre-implanted insert or machined notch, is sometimes described as the non-precracked (NPC) toughness. NPC toughness may be of interest, as it can represent manufacturing or processing defects, such as foreign object debris in a laminate or an error during machining. 5.2.2 The next increment of growth, initiated from the sharp crack tip assumed to be present after the first increment, is sometimes defined as the precracked (PC) toughness. PC toughness may be of interest, as it is more representative of the resistance to delamination growth from a naturally occurring or damage-induced delamination. 5.2.3 The remaining increments of growth, collectively forming an R-curve, provide information on how G Ic evolves as the delamination advances. In unidirectional tape laminates, the R-curve is often increasing due to bridging of nested fibers across the delamination plane, artificially increasing G Ic . For 2-D woven laminates for which there is little interply nesting, the R-curve may be flat. 5.2.4 The increments of growth in which the R-curve is flat, and G Ic has reached a steady state value defined as G IR , may be of interest and may also useful in design and analysis. 5.3 This test method for measurement of G Ic of CMC materials can serve the following purposes: 5.3.1 To establish quantitatively the effect of CMC material variables (fiber interface coatings, matrix structure and porosity, fiber architecture, processing and environmental variables, conditioning/exposure treatments, etc.) on G Ic and the interlaminar crack growth and damage mechanisms of a particular CMC material; 5.3.2 To determine if a CMC material shows R-curve behavior where G Ic changes with crack extension or reaches a stable value at a given amount of delamination growth. Fig. 2 shows R-curve behavior for a SiC-SiC composite ( 1 ) ; 5.3.3 To develop delamination failure criteria and design allowables for CMC damage tolerance, durability or reliability analyses, and life prediction; Note 3: Test data can only reliably be used for this purpose if there is confidence that the test is yielding a material property and not a structural, geometry-dependent, property. 5.3.4 To compare quantitatively the relative values of G Ic for different CMC materials with different constituents and material properties, reinforcement architectures, processing parameters, or environmental exposure conditions; and 5.3.5 To compare quantitatively the values of G Ic obtained from different batches of a specific CMC material, to perform lot acceptance quality control, to use as a material screening criterion, or to assess batch variability.

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