1. Visão geral
1.1 This test method includes methods for evaluating the tensile properties of vulcanized thermosetting rubber and thermoplastic elastomers. This test method can not be used to test hard glue and materials with high hardness and low elongation. O método de teste é o seguinte:

Método A — Straight bar and dumbbell samples

Método B — Espécime anular

Observação 1 -the results of the two tests are incomparable.

1.2 Unidades baseadas no SI ou não SI são consideradas unidades padrão desta norma. Since the results of using different unit systems may be different, as diferentes unidades devem ser usadas separadamente e não misturadas.

Segurança

2 Referências
D 1349 Especificação de borracha — Standard test temperature

D 1566 Rubber related terminology

D 3182 Especificação de borracha — Materiais, equipment and procedures for making standard compounds and standard vulcanization test pieces

D 3183 Especificação de borracha — Preparation of test pieces from finished products

D 4483 Standard test methods for rubber and carbon black industrial species – Specification for measurement accuracy

2.2 ASTM Annex

Preparação de amostras anulares, Método B

Padrões ISO

ISO 37 – Methods for determination of tensile stress-strain properties of vulcanized or thermoplastic rubber

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

3 Terminologia
3.1 Definitions

3.1.1 Deformação elástica de longo prazo — The residual deformation of the sample after elongation under a certain action, when the applied force is relieved, é expresso como uma porcentagem do comprimento original.

3.1.2 Long stretching deformation — The long stretching deformation of the pulled dumbbell sample is closely pressed to the cross section.

3.1.3 Força de tração — The maximum force generated in the process of breaking the sample.

3.1.4 Resistência à tracção — the stress used when drawing the sample

3.1.5 Tensão de extensão constante — the stress generated when a sample of regular section is stretched to a specific length.

3.1.6 Thermoplastic elasters — a material similar to rubber, mas ao contrário da borracha vulcanizada comum, pode ser processado e reciclado como plástico.

3.1.7 Alongamento na ruptura — the elongation of the specimen when it breaks during continuous stretching.

3.1.8 Ponto de rendimento — The point on the stress-strain curve where the velocity of the stress change with respect to strain becomes 0 and opposite before the final failure of the specimen.

3.1.9 Tensão de rendimento — O nível de tensão no ponto de escoamento

3.1.10 Estresse de rendimento — O nível de estresse no ponto de escoamento

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

Method Description
4.1 For the test of tensile properties, samples are first cut from the sample material, including two parts: sample preparation and test. The shape of the specimen can be dumbbell, anel ou barra reta, e a forma da seção é regular.

4.2 Determinação da resistência à tração, estresse de fixação, ponto de escoamento e alongamento na ruptura sem pré-extensão da amostra. A determinação da resistência à tração, estresse de fixação, yield point and elongation at break for the specimen with normal section is based on the original cross-sectional area of the specimen.

4.3 Long-term deformation by stretching and long-term deformation by tearing, measure the deformation of the sample after stretching and shrinking according to the prescribed method.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

Key Points and Applications
5.1 Os materiais ou produtos envolvidos neste teste precisam ser submetidos a força de tração no processo de aplicação real. This test is to determine such tensile properties. No entanto, the tensile properties do not directly represent the whole situation of the final use of the product, because the product needs to cover a wide range of potential use conditions in actual use.

5.2 Tensile properties are dependent on materials and test conditions (velocidade de tração, testar temperatura e umidade, geometria de amostra, ajuste pré-teste, etc.). Portanto, os resultados dos testes de materiais nas mesmas condições são comparáveis.

5.3 Test temperature and tensile speed have significant effects on tensile properties, que deve ser rigorosamente controlado. And the effect varies with different materials.

5.4 A deformação elástica de longo prazo representa a deformação residual da amostra. Representa a deformação a longo prazo e a recuperação parcial da amostra após alongamento e retração. Portanto, os processos de estiramento e retração (e outras condições de teste) need to be tightly controlled to ensure comparable results.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

6 Equipamento
6.1 Máquina de tração — The tensile testing machine shall have an electric drive mechanism to ensure that the separation speed of the sample chuck is constant 500±50mm/min, and the minimum stroke is 750mm(Veja a nota 1). The testing machine should have a suitable dynamometer and reading recording system to ensure that the measured force deviation is within ±2%. Se o alcance da máquina de teste não puder ser alterado (por exemplo, o dinamômetro de pêndulo), then the deviation of the measured force when the sample is broken is ±2% of the full range of the dynamometer, and the accuracy of the measured minimum force is 10%. If the dynamometer has an automatic compensation function in the direct measurement of tensile stress, then the compensation function for the cross-sectional area of the specimen should be turned off during the measurement. The recording device should be fast enough to measure the force and ensure the required accuracy during the whole process of specimen failure. If the testing machine does not have a recording device, there should be an indicator to indicate the maximum force value during stretching. O alongamento deve ser medido no sistema de teste com um incremento mínimo de 10%.

Observação 1 — Se a velocidade de tração usada for 1000±100mm/min, deve ser indicado no relatório de teste. In case of doubt, the test should be repeated at a speed of 500mm/min.

6.2 High and low temperature test box — the test box should meet the following requirements:

6.2.1 Na câmara de teste, there should be a heat flow around the position of the chuck and the shaft, a velocidade surround é 1 a 2m/s, and the temperature is kept within the range of 2 ° C of the required temperature deviation.

6.2.2 Use the calibrated temperature measuring device to measure the actual temperature near the chuck and shaft.

6.2.3 The test chamber shall have an exhaust ventilation device to discharge the gas released in high temperature (amostra) into the atmosphere.

6.2.4 Antes do teste, a amostra deve ser colocada verticalmente perto do mandril e do eixo para ajuste. Specimens should not be in contact with each other or with the walls of the test chamber except for transient contact caused by agitation of the surrounding air.

6.2.5 Place the chuck appropriately to facilitate operation in high and low temperature environments. Desta maneira, the dumbbell or straight strip specimens are placed into the chuck for as short a time as possible to reduce the temperature change of the test chamber.

6.2.6 The dynamometer should be suitable for working at the test temperature, or have good insulation with the test chamber.

6.2.7 Elongation measuring device shall be provided in the test chamber. If a ruler is used to measure the elongation of the specimen scale, the ruler should be placed parallel to the scale close to the path of the chuck movement and can be controlled from outside the test chamber.

6.3 Thickness gauges — Thickness gauges shall meet the requirements of Specification D 3767(Método A). For annular specimens, veja o artigo 14.10 of this test method.

6.4 Measurement of tensile long-term deformation — Use test equipment as described in 6.1 or as shown in Figure 1. The stopwatch or other timing device should have a range greater than 30min, and the measuring accuracy of the ruler or other measuring device for elongation should be within 1%.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

7 Seleção de amostras
7.1 The following points should be considered when selecting samples

7.1.1 The anisotropy and orientation of the material caused by the flow during preparation and treatment can affect the tensile properties. Portanto, in the preparation of dumbbell or straight bar specimens, under the premise of knowing the calendering direction, a direção do corte da amostra deve ser paralela à direção da calandragem. For annular specimens, the orientation characteristics are usually averaged to a certain extent.

7.1.2 A menos que especificado de outra forma, for thermoplastic rubbers or elasteers, specimens shall be cut from injection molded specimens with a thickness of 3.0±0.3mm, and the test results obtained from specimens of other thicknesses shall be comparable. The samples should be two sets of perpendicular and parallel forming flow directions. The size of the test piece or test plate should be able to meet the test requirements.

7.1.3 The elongation of the annular specimen can be measured by the separation of the collet, but the elongation distribution on the radius width of the specimen is inconsistent. Para reduzir este efeito, the sample width should be smaller than the diameter of the annular sample.

7.1.4 When the sample is used for ordinary tensile test, the failure of the sample generally occurs in the chuck. Portanto, the straight bar specimen is used only when the sample cannot be made of other shapes. For non-destructive stress-strain or material modulus experiments, straight strip specimens should be used.

7.1.4 O tamanho da amostra depende dos requisitos do material, o equipamento de teste e a amostra usada para o teste. Para materiais com baixo alongamento na ruptura, longer specimens can be used to improve the accuracy of elongation measurement.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

Calibração de equipamentos de teste
8.1 Calibrate the test machine according to Procedure A of Specification E 4 for dynamometers of measuring precision type, and calibrate one or more force points according to the 7 e 18 test of specification E 4. For pendulum dynamometers, siga as etapas a seguir para calibrar:

8.1.1 Coloque uma extremidade da amostra do haltere no mandril da máquina de teste.

8.1.2 Remova o mandril inferior da máquina de teste, isto é,, the clamping mechanism of the sample is on the upper chuck of the testing machine.

8.1.3 Instale um gancho no mandril inferior para segurar a extremidade inferior da amostra

8.1.4 Hang a weight with a known weight on the hook, so that a certain mass can be temporarily applied to the lower fixture of the sample (Veja a nota 2).

8.1.5 Turn on the fixture movement monitoring device and keep it running until the weight is free to hang on the sample in the ordinary test.

8.1.6 If a disc or ruler (or equivalent tester for stress compensation) does not indicate force values within the specified accuracy, the equipment should be effectively checked for faults (por exemplo. friction on shafts or other moving parts). Deve ser determinado que a massa do mandril inferior e do gancho também seja levada em consideração.

8.1.7 Depois que o atrito e outras falhas da máquina de teste forem eliminados, the testing machine is calibrated to know that the weight is measured at three points at about 10, 20 e 50% da escala completa da máquina de testes. If ratchets and spines are used in normal testing, they should also be used in calibration. Friction is checked by mounting a ratchet.

Observação 3 — There should be a device to prevent weights from falling from the test machine.

8.2 Uma mola pode ser usada para calibração rápida aproximada.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

9 Temperatura de teste
9.1 A menos que especificado de outra forma, a temperatura de teste padrão é 23±2℃. A amostra deve ser ajustada em 23 °C durante pelo menos 3 horas. Se o material for afetado pela umidade, a amostra deve ser condicionada a 50±5%R.H. por mais que 24 horas antes do teste. Se testado em outras temperaturas, a temperatura listada na Especificação D 1349 Deve ser usado.

9.2 If the test is carried out at A temperature higher than 23℃, a amostra do método A deve ser pré-aquecida por 10±2min; Method B should be preheated for 6±2min. Antes de cada intervalo de teste, the specimens are placed in the test chamber separately, so that all specimens are continuously subjected to the same warm-up time. Preheating tests at high temperatures should be strictly limited to prevent persulphation and thermal aging.

Observação 3 — Aviso: Entre outros avisos, use insulated, cold gloves to protect hands from high and low temperatures. Uma máscara deve ser usada durante experimentos de alta temperatura para evitar a inalação de gases tóxicos quando a porta da caixa experimental for aberta.

9.3 Para teste de baixa temperatura, a amostra deve ser pré-resfriada por pelo menos 10 minutos.

Método de teste A — Straight bar and dumbbell specimens

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

10 Equipamento
10.1 Cutting Knife — The shape and dimensions of the cutting knife shall be as shown in Figure 2. The inside of the narrow part of the cutter shall be perpendicular to the cutter end face and at least 5mm from the cutter end face shall be polished. The shape of the cutter should remain unchanged without defects. (Veja a nota 4)

Observação 4 — A condição da ferramenta de corte pode ser determinada observando o ponto de fratura da amostra. The fractured sample was removed from the chuck and spliced along the fracture surface to observe whether the sample failure occurred at the same location. Se a falha ocorrer no mesmo local, it means that the cutter may become blunt, defeituoso, ou dobrado neste local.

10.2 Marking lines — Two marking lines drawn on the sample to measure elongation and strain are called marking lines (Veja a nota 5). The marker shall include a flat plate with two bumps parallel to each other. A superfície elevada (paralelo à superfície da placa) deve ter um plano longo e estreito, e as duas faces devem ser mantidas no mesmo plano. O plano elevado é 0.05 até 0,08 mm de largura e pelo menos 15 mm de comprimento. The Angle between the plate and the bulge was at least 75º. A distância entre os centros dos dois planos elevados deve ser mantida dentro 1% of the required or target distance deviation. A handle shall be included on the back or top of the marker.

Observação 4 — No marking is required if contact extensionometers are used.

10.3 Ink Marks — Use um apartamento, superfície dura (madeira dura, metal, ou plástico) to make ink or toner marks. The ink or toner should be firmly bonded to the sample, not corroding the sample, and contrast with the color of the sample.

10.4 Chuck — O medidor de teste possui duas pinças, um dos quais está conectado ao dinamômetro.

10.4.1 The chuck of the test dumbbell sample should have a self-tightening device to generate constant pressure on the surface of the chuck, and the clamping force should increase with the increase of elongation to prevent sliding and make the failure occur in the narrow part of the sample. A constant pneumatic chuck is also applicable. There is a special part in the broken part of the fixture so that the sample can be inserted into the fixture with the same length and the stress distribution is uniform.

10.4.2 The fixture used for testing straight strip samples shall have pneumatic fixture, boca de braçadeira ou fivela de parafuso, so that the clamping force of the fixture can be applied evenly to the entire width of the sample.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

11 Amostra
11.1 Amostras de halteres — Quando possível, specimens should be injection molded or cut from specimens 1.3 até 3,3 mm de espessura. The thickness and size of the specimen can be cut by one test method (see Specification D 3182). A peça de teste pode ser feita diretamente ou cortada e polida a partir do produto acabado. If the test piece is prepared directly from the finished product, a superfície não deve ser de couro duro ou tecido. According to the requirements of specification D 3183. All specimens shall be cut parallel to the length of the specimen, salvo especificação em contrário. Se a amostra for preparada de acordo com a especificação D 3182, sua espessura deve ser de 2,0±0,2mm e cortada ao longo da orientação do material. Use C type cutter (FIGO. 2), use a simple stamping device, and ensure the smoothness of the cut surface. .

11.1.1 Rotulagem de amostras de halteres — Dumbbell specimens shall be marked as described in 10.2, and the specimens shall not be subjected to tension when marked. The marking line should be drawn on the narrow part, at the same distance from the center of the sample and perpendicular to the vertical axis. The distance between the two marks is 25.00±0.25mm for type C and type D samples. The other is 50.00±0.5mm

11.1.2 dumbbell sample thickness measurement — The thickness of the sample should be measured at three points, one at the center and two at the ends of the narrow part. The median of the three values is used to calculate the cross-sectional area. Se a faixa da espessura da amostra for maior que 0.08, the sample is rejected. A largura da amostra pode ser calculada de acordo com a largura da parte de trabalho da fresa.

11.2 Amostras de tira reta — If dumbbells or annular specimens cannot be cut from the sample, amostras de tira reta (por exemplo., narrow strips, tubos pequenos, or fine electrical insulation) can be cut. A amostra deve ser longa o suficiente para caber no acessório. The marking is made as 11.1.1. Para calcular a área da seção transversal de teste do tubo, a massa, comprimento e densidade do tubo devem ser usados. A área da seção transversal é calculada da seguinte forma:

A=M/DL(1)(1)

Onde:

A= área da seção transversal,cm2

M = massa,g

D= densidade,g/cm3

eu= comprimento,cm

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

12 Passos
12.1 Determinação da tensão de tração, resistência à tração e ponto de escoamento — Carregue a amostra do haltere no dispositivo da máquina de teste, pay attention to adjust the gripping symmetry of the sample, de modo que a força de tração seja distribuída uniformemente na seção da amostra. Isso evitará a superestimação da força de tração da amostra. The test speed is 500±50mm/min(Veja a nota 7) unless special requirements are required. Start the testing machine and pay attention to the marking to prevent the influence of parallax. The force values at special elongation and at fracture of the sample were recorded. Elongation can be measured using extensionmeters, automated plotting, or optical tracking systems. A precisão da medição do alongamento na fratura está dentro 10%. The calculation is given in 13.

Observação 8 — Se o ponto de escoamento da amostra estiver abaixo 20% alongamento quando a velocidade de teste é 500±50mm/min, a velocidade de teste pode ser reduzida para 50±5mm/min. Se o ponto de escoamento da amostra ainda estiver abaixo 20% alongamento, a velocidade de teste pode ser reduzida para 5±0,5 mm/min. Sample speed should be recorded.

12.2 Determinação da deformação elástica de longo prazo — The sample is loaded into the testing machine or device described in 6.1 como mostrado na figura 1. Care should be taken to adjust the gripping symmetry of the sample so that the tensile force is evenly distributed on the sample cross section. The speed of the chuck separation should be as constant as possible, so that the time to reach the prescribed elongation is 15s, and this elongation is maintained for 10min. Depois de 10 minutos, the load was released immediately and allowed to return freely for 10min. Depois disso, the residual deformation within the standard distance was measured, and the measurement accuracy was 1% da distância original. Use a stopwatch to track the time. Ver 13 para o cálculo.

12.3 Measurement of long-term fracture deformation — Depois que a amostra for quebrada por 10 minutos, the sample should be carefully spliced together to measure the residual deformation within the standard distance, and the calculation is shown in 13

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

13 Cálculo
13.1 Cálculo de resistência em qualquer alongamento:

where

T(XXX)= força no alongamento (XXX)%,MPa

F(XXX)= tensão no alongamento específico,Minnesota

A= cross-sectional area of the sample,m2

13.2 Cálculo da resistência ao escoamento

where

S(estresse)= limite de escoamento,MPa

F(sim)= força de rendimento,Minnesota

A= cross-sectional area of the sample,m2

13.3 The yield point is evaluated as the point on the stress-strain curve where the velocity of the stress change with respect to strain becomes zero and opposite before the final failure of the specimen.

13.4 Cálculo da resistência à tração

where

TS = resistência à tração,MPa

F(SER)= maximum force at fracture,Minnesota

A= cross-sectional area of the sample,m2

13.5 Compute the elongation at any elongation;

where

E= alongamento percentual (distância em escala),%

L= distância observada dentro da distância padrão da amostra,milímetros

eu(0)= length of the sample’s original marking distance,milímetros

13.6 Elongation at break is calculated by substituting L at the time of sample fracture into Equation 5.

13.7 Fórmula 5 can also be used to calculate long-term deformation, as long as L in the formula is substituted by the residual deformation after 10 minutos.

13.8 Test Results — Os resultados dos testes são expressos como a mediana dos resultados de três amostras consecutivas independentes. Em dois casos especiais, cinco amostras foram testadas e o valor mediano das cinco amostras foi relatado.

13.8.1.Caso especial 1 — When the results of one or two samples in the test do not meet the specified measurement.

13.8.2 Caso especial 2 — For arbitral tests.

Método B — Espécime anular

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

14 Equipamento
14.1 Cortador — A circular cutter is shown in Figure 3. Use a cutting knife to cut the annular sample from the flat test piece, and install a part of the upper shaft of the cutting knife into the rotary compression device, under which the test piece can be fixed in the rubber fixing device.

14.1.1 Retentor de profundidade da lâmina — The cylindrical disk in the retainer shall be at least 0.5mm thicker than the thickness of the rubber sheet to be cut. Its diameter should be smaller than the inner diameter of the sample, para que a saliência da lâmina possa ser ajustada a partir da ferramenta de corte. Veja a figura 3

14.2 Placa de fixação de borracha — A device for holding rubber in place during cutting, the upper and lower surfaces parallel to each other, and made of hard polymeric materials (cola dura, poliuretano e polimetilmetacrilato). Holes of about 1.5mm in diameter are distributed at intervals of 6 to 7mm through the center of the plate. All these holes shall communicate with the mold cavity inside to reduce the air pressure used to hold the test piece. Figura 4 is used to hold the standard test piece (cerca de 150×150×2mm) durante o corte.

14.3 Fonte de pressão de ar — A vacuum pump can be used to maintain a suction force of 10kPa on the specimen at the center of the gripper mold cavity.

14.4 Soapy water — Use neutral soapy water to lubricate the knife.

14.5 Corte rotativo — Use a precision rotary machine or other equipment that can provide a speed of at least 30rad/s to cut the test piece. The cutter rotating device shall be mounted on a horizontal plane with a vertical positioner to support the rotating connecting rod and the shaft used for the cutter. A excentricidade do eixo rotativo deve ser inferior a 0,01 mm.

14.6 Built-in table — There shall be a table or other device that can be moved along the x-y axis respectively to hold and position the test piece so that the test piece corresponds to the axis of rotation of the rotary cutter.

14.7 Máquina de teste de tração — shall comply with the requirements described in 6.1.

14.8 Dispositivo de teste — The fixture of the annular sample is shown in Figure 5. A máquina de teste deve ser calibrada de acordo com 8 articles.

14.9 Test chambers — High and low temperature test chambers shall meet the requirements in 6.2.

14.9.1 O acessório não deve ser adequado apenas para testes em temperatura ambiente. No entanto, sob temperatura especial, lubrificação apropriada deve ser usada para garantir a lubrificação do eixo rotativo.

14.9.2 O dinamômetro deve ser adequado para uso em temperatura operacional ou bem isolado da câmara de teste.

14.10 Medidores de espessura — Thickness gauges shall meet the requirements of Specification D 3767(Método A).

14.10.1 The main components of the thickness gauge, uma superfície de medição superior cilíndrica (longitudinal axis along the vertical direction) pelo menos 12 mm de altura e 15,5 ± 0,5 mm de diâmetro. In order to fit the small annular sample, the measuring head with diameter of 15.5mm is used to measure, e a medição não causará o alongamento da amostra. The bottom of the cylindrical surface can be cut off half along the center so that there is no interference when measuring small samples. Uma extremidade de medição curva também pode ser usada.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

15. Espécime anular

15.1 Amostras anulares ASTM — Existem dois tipos, generally 1-shaped specimens are used

15.1.1 Tamanho da amostra

Tipo 1

The inner perimeter is 50.0±0.01mm

O diâmetro interno foi 15,92±0,003mm

The radial width is 1.0±0.01mm

The thickness is 1.0~3.3mm

Tipo 2

The inner perimeter is 100.0±0.2mm

O diâmetro interno foi 29,8±0,06mm

The radial width is 2.0±0.02mm

The thickness is 1.0~3.3mm

15.2 Amostras anulares ISO — Specimens are classified as normal and small according to ISO 37, que especifica seus procedimentos de teste específicos.

ordinário

The inner diameter is 44.6±0.2mm

The outer diameter is 52.6±0.2mm

The thickness is 4.0±0.2mm

Tamanho pequeno

Diâmetro interno 8,0±0,1mm

Diâmetro externo 10,0±0,1mm

The thickness is 1.0±0.1mm

15.3 Corte a amostra anular do tubo — the diameter of the annular sample should be determined by the wall thickness of the pipe and should meet the requirements of the product.

15.4 Preparação da amostra de corte — Place the blade in the holder of the cutter and adjust the depth of the blade. Coloque o cortador na prensa rotativa e ajuste o eixo ou mesa de modo que a parte inferior do suporte da lâmina fique 13mm acima da placa de retenção da amostra. Shrink the stopper with the rotating shaft moving vertically. This allows the end of the blade retainer to penetrate the surface of the plate. The sample was placed into the gripper and the cavity pressure was reduced to 10kPa. Molhe a superfície da peça de teste com água e sabão neutro. The cutter should be stopped after reducing the cutter at a constant speed, and the cutter gripper should not touch the test piece at this time. Adjust blade depth if necessary. Reset the shaft before the next cutting.

15.5 Preparation of a sample cut from a tube — A shaft is inserted into the tube, the diameter of which is slightly larger than the diameter of the tube. Place the shaft and tube together on the machine tool. The specimen of the required axial thickness is cut from the sample with the blade or cutter on the machine tool. For thin-walled tubes, when laid flat, a cutter with two parallel blades can be used to cut.

15.6 Annular sample:

15.6.1 Perimeter — The inner perimeter can be measured with a cone or gauge. Nenhuma tensão pode ser usada para alterar a elipticidade da amostra anular durante a medição. O perímetro mediano pode ser baseado no perímetro interno, meridional width, and π(3.14).

15.6.2 Largura radial — Distribute three measuring points equally on the circumference of the specimen as per the thickness gauge in 14.10.

15.6.3 Grossura — The thickness of the disk from the inner circle to the outer circle can be measured by a thickness meter according to specification D 3767 when cutting annular specimens.

15.6.4 Área transversal — Cross-sectional area was calculated as the median of three measurements: radial width and thickness. Para amostras de paredes de tubos finos, the cross-sectional area was calculated using the axial length of the cutter and the wall thickness.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

16 Processo
16.1 Determinação da tensão de tração, resistência à tracção, alongamento na ruptura e ponto de escoamento de amostras anulares – com lubrificação adequada dos eixos com dispositivo lubrificante, como óleo mineral ou óleo de silicone. Should choose to use the prescribed and have no impact on the material. O cálculo e ajuste da posição inicial do centro do eixo dos dois acessórios são os seguintes:

Onde:

IS= initial distance from the center of the jig axis,milímetros

C(TS)= perimeter of the sample, para tipo 1 amostra é o diâmetro interno, para tipo 2 amostra é o diâmetro,milímetros

C(SP)= circumference of the jig shaft,milímetros

The test speed was 500±50 mamms (ver notas 7 e 8), unless otherwise required. Start the test machine and record the force and the relative displacement of the two jig axes. Elongation and stress were recorded at fracture. The calculations are given in Section 17,

Observação 8 — The test speed was 100±10mm/min using small ring type samples of ISO.

16.2 Experimentos em temperaturas fora do padrão — Use a câmara de teste conforme descrito em 6.2 and read the warning in Note 2. For tests higher than 23 ° C, a amostra foi pré-aquecida a esta temperatura por 6±2min. Para testes abaixo da temperatura ambiente, a amostra deve ser ajustada a essa temperatura por pelo menos 10 minutos. A temperatura de teste em D 1349 deve ser usado. Test pieces shall be placed in test chambers separately to meet requirement 9.2.

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

17 Cálculo
17.1 Exceto por um ponto importante, the stress-strain properties of the ring specimen are calculated as those of the dumbbell or straight strip specimen. Quando a amostra anular é esticada, the stress distribution of each edge of the annular specimen is not uniform in width (da esquerda para a direita). The initial inner diameter of the sample is smaller than the initial outer diameter. Portanto, the stress in the inner test is greater than that in the outer test in the sample stretching, caused by the different initial size.

17.2 The following options are available for calculating tensile and breaking strengths.

17.2.1 Fixed elongation stress — The median perimeter of the annular specimen was used to calculate the elongation. The reason for using the median perimeter is that it corresponds to the average over the edges of the annular specimen.

17.2.2 Alongamento na ruptura — O perímetro interno da amostra anular é usado como base para o cálculo, as it corresponds to the maximum stress on each edge of the specimen. This position is also the starting position of the sample failure.

17.3 A tensão de extensão constante é calculada de acordo com a Equação 2 em 13.1

17.3.1 O alongamento usado para determinar a força na Equação 2 (13.1) é calculado da seguinte forma

Onde:

E= alongamento,%

L= increase in the distance between fixtures,milímetros

MC(TS)= perímetro médio da amostra,milímetros

17.3.2 In Equation 7, the distance between fixtures at fixed extension is calculated using the following equation:

17.4 O ponto de rendimento é calculado de acordo com a Equação 3 em 13.2

17.5 Usar 13.3 to determine the yield stress. Como a tensão de escoamento é usada para avaliar as propriedades gerais do material, o perímetro mediano é usado para calcular.

17.6 Calculate tensile strength according to Formula 4 em 13.4.

17.7 Elongation at break is calculated according to the following formula (ver notas 9 e 10)

Onde:

E= alongamento na ruptura,%

L= the increased distance of the fixture at break,milímetros

CI(TS)= perímetro interno inicial do padrão,milímetros

17.8 The inner perimeter can be used for both types of specimens (ver 15.1.1 dimensões). O perímetro interno do tipo 2 amostras anulares são calculadas usando o diâmetro interno.

Observação 9 — Equações 7 e 8 can only be used if the initial spacing of the fixture is adjusted according to Equation 7.

Observação 10 — Caution should be taken when using this method because stresses at elongations slightly below the elongation at break (4 para 5%) may not be calculated when different sizes are used to calculate 1) fixed elongation stress (menos do que a tensão de ruptura) e 2) alongamento na ruptura (ver 20.1 e 20.2).

ASTM D412-0 “Método de teste de tração para borracha vulcanizada e elastômeros termoplásticos”

18 Relatório
18.1 The report should include the following:

18.1.1 Based on the results of Section 13 ou 17

18.1.2 Tipo de amostra e descrição, de acordo com o tipo de cortador de 13 seções, em americano, unidades caseiras ou métricas

18.1.3 Date of experiment

18.1.4 Teste de velocidade

18.1.5 Temperatura e umidade do laboratório

18.1.6 Temperatura de teste (se não 23±2℃)

18.1.7 Date of vulcanization or (e) rubber preparation, if possible

19 Precisão no desvio (omitido)

20 Palavras-chave (omitido)