Part 4 MECHANICAL PROPERTIES

Size: px

Start display at page:

Download "Part 4 MECHANICAL PROPERTIES"

Beatrix Norris
6 years ago
Views:

1 Part 4 MECHANICAL PROPERTIES Fiber Composite Materials M. S. Ahmadi 192 TENSILE PROPERTIES Tensile properties, such as tensile strength, tensile modulus, and Poisson s ratio of flat composite laminates, are determined by static tension tests in accordance with ASTM D3039. Fiber Composite Materials M. S. Ahmadi 193 1

Recommended cross-head speed: 2 mm/min Fiber Composite Materials M. S.

2 As end tab materials, balanced [0=90] cross-ply tabs of nonwoven E-glass epoxy have shown satisfactory results. Any high-elongation (tough) adhesive system can be used for mounting the end tabs to the test specimen. Recommended cross-head speed: 2 mm/min Fiber Composite Materials M. S. Ahmadi 194 COMPRESSIVE PROPERTIES Compressive properties of thin composite laminates are difficult to measure owing to sidewise buckling of specimens. A number of test methods and specimen designs have been developed to overcome the buckling problem ASTM D3410 Fiber Composite Materials M. S. Ahmadi 195 2

3 FLEXURAL PROPERTIES Flexural properties, such as flexural strength and modulus, are determined by ASTM test method D790. In this test, a composite beam specimen of rectangular cross section is loaded in either a three-point bending mode or a four-point bending mode. Fiber Composite Materials M. S. Ahmadi 196 Using a homogeneous beam theory, the flexural strength in a threepoint flexural test is given by Flexural modulus is calculated from the initial slope of the load deflection curve: where m is the initial slope of the load deflect ion curve. Fiber Composite Materials M. S. Ahmadi 197 3

4 IMPACT PROPERTIES A variety of standard impact test methods are available for metals (ASTM E23) and unreinforced polymers (ASTM D256). Some of these tests have also been adopted for fiber-reinforced composite materials. CHARPY, IZOD, AND DROP-WEIGHT IMPACT TEST Charpy and Izod impact tests are performed on commercially available machines in which a pendulum hammer is released from a standard height to contact a beam specimen (either notched or unnotched) with a specified kinetic energy. A horizontal simply supported beam specimen is used in the Charpy test, whereas a vertical cantilever beam specimen is used in the Izod test. Fiber Composite Materials M. S. Ahmadi 198 Charpy impact tests ASTM D6110 For a typical fiber reinforced polymer Charpy specimen, L = 126 ± 1 mm, D = 12.7 ± 0.15 mm, and 3.00 mm < w < 12.7 mm Izod impact tests The dimensions of a standard specimen for ASTM D256 are mm ( in). The most common specimen thickness is 3.2 mm (0.125 in), but the width can vary between 3.0 and 12.7 mm(0.118 in and in). Fiber Composite Materials M. S. Ahmadi 199 4

5 Fiber Composite Materials M. S. Ahmadi 200 ASTM D 5628 Fiber Composite Materials M. S. Ahmadi 201 5

6 The drop -weight impact test uses the free fall of a known weight to supply the energy to break a beam or a plate specimen. The specimen can be either simply sup ported or fixed. The kinetic energy of the falling weight is adjusted by varying its drop height. The impact load on the specimen is measured by instrumenting either the striking head or the specimen supports. Energy absorbed by the specimen is calculated as Fiber Composite Materials M. S. Ahmadi 202 Composite Material Stiffness Predictions Rule of Mixtures (ROM) ROM with Efficiency Factor Hart Smith 10% rule Classical Laminate Analysis Fiber Composite Materials M. S. Ahmadi 203 6

7 Lamina Axis Notation Fiber Composite Materials M. S. Ahmadi 204 Example Material for Analysis Fiber Composite Materials M. S. Ahmadi 205 7

8 Fiber Composite Materials M. S. Ahmadi 206 Fiber Composite Materials M. S. Ahmadi 207 8

9 Rule of Mixtures: Efficiency Factor The Efficiency Factor or Krenchel factor can be used to predict the effect of fibre orientation on stiffness This is a term that is used to factor the Rule of Mixtures formula according to the fibre angle Fiber Composite Materials M. S. Ahmadi 208 Fiber Composite Materials M. S. Ahmadi 209 9

10 Fiber Composite Materials M. S. Ahmadi 210 Fiber Composite Materials M. S. Ahmadi

11 Fiber Composite Materials M. S. Ahmadi 212 Fiber Composite Materials M. S. Ahmadi

12 Fiber Composite Materials M. S. Ahmadi 214 Fiber Composite Materials M. S. Ahmadi

13 Fiber Composite Materials M. S. Ahmadi 216 Fiber Composite Materials M. S. Ahmadi

14 Fiber Composite Materials M. S. Ahmadi 218 Classical Laminate Analysis Fiber Composite Materials M. S. Ahmadi

Advanced Structures and Composites Center, University of Maine 35 Flagstaff Road Orono, Maine Benjamin Herzog, Quality Manager

Advanced Structures and Composites Center, University of Maine 35 Flagstaff Road Orono, Maine Benjamin Herzog, Quality Manager IAS Accreditation Number Company Name Address Contact Name Telephone (207) 581-2360 Effective Date of Scope November 16, 2018 Accreditation Standard ISO/IEC 17025:2005 Fire TL-255 Composites Center, University