G. Savage/ Engineering Failure Analysis 17 (2010)92-115 Mr003Mx:421 Fig. 7. A Formula 1 car is always accelerating. teristics. The pursuit of lower weight and improved performance have both stimulated the introduction of new technology in both design and construction. The structural components of the car must be stiff, strong enough to satisfy the loading requirements, tolerant of and resistant to, impact damage and be of minimum weight. The solution to this problem is achieved by optimising the geometry the quality of construction and by using the most appropriate materials. The quest for maximum structural efficiency has resulted in a progression of different technologies throughout the history of Grand Prix racing. Much of the development within Formula 1 has shadowed that taking place within the aerospace industry This is not surprising when one considers the similarity of their objectives 2. Composite materials y opposites are defined as"materials in which two or more constituents have been brought together to produce a new material consisting of at least two chemically distinct components, with resultant properties significantly different to those of the individual constituents". A more complete description also demands that the constituents must also be present in rea- onable proportions. Five percent by weight is arbitrarily considered to be the minimum. The material must furthermore be considered to be"man made That is to say it must be produced deliberately by intimate mixing of the constituents. An alloy which forms a distinct two phase microstructure as a consequence of solidification or heat treatment would not therefore be considered as a composite. If on the other hand, ceramic fibres or particles were to be mixed with a metal to produce a mate- rial consisting of a dispersion of the ceramic within the metal; this would be regarded as a composite. On a microscopic scale composites have two or more chemically distinct phases separated by a distinct interface. This interface has a major influence on the properties of the composite. The continuous phase is known as the matrix. Generally the properties of the matrix are greatly improved by incorporating another constituent to produce a composite. A composite nay have a ceramic, metallic or polymeric matrix. The second phase is referred to as the reinforcement as it enhances the properties of the matrix and in most cases the reinforcement is harder, stronger and stiffer than the matrix [1]. The measured strengths of materials are several orders of magnitudes less than those calculated theoretically. Further ore the stress at which nominally identical specimens fail is subject to a marked variability. This occurs because of the presence of inherent flaws within the material [2]. There is always a distribution in the size of the flaws and failure under load initiates at the largest of these. Griffith derived an expression relating failure stress to flaw size(a) K (1) here af=failure stress, Kic is the material's fracture toughness and y a geometrical constant. As Eq (1)shows, the larger the flaw size the lower will be the failure stress( Fig 8)teristics. The pursuit of lower weight and improved performance have both stimulated the introduction of new technology in both design and construction. The structural components of the car must be stiff, strong enough to satisfy the loading requirements, tolerant of and resistant to, impact damage and be of minimum weight. The solution to this problem is achieved by optimising the geometry, the quality of construction and by using the most appropriate materials. The quest for maximum structural efficiency has resulted in a progression of different technologies throughout the history of Grand Prix racing. Much of the development within Formula 1 has shadowed that taking place within the aerospace industry. This is not surprising when one considers the similarity of their objectives. 2. Composite materials Composites are defined as ‘‘materials in which two or more constituents have been brought together to produce a new material consisting of at least two chemically distinct components, with resultant properties significantly different to those of the individual constituents”. A more complete description also demands that the constituents must also be present in rea￾sonable proportions. Five percent by weight is arbitrarily considered to be the minimum. The material must furthermore be considered to be ‘‘man made”. That is to say it must be produced deliberately by intimate mixing of the constituents. An alloy which forms a distinct two phase microstructure as a consequence of solidification or heat treatment would not therefore be considered as a composite. If on the other hand, ceramic fibres or particles were to be mixed with a metal to produce a mate￾rial consisting of a dispersion of the ceramic within the metal; this would be regarded as a composite. On a microscopic scale composites have two or more chemically distinct phases separated by a distinct interface. This interface has a major influence on the properties of the composite. The continuous phase is known as the matrix. Generally the properties of the matrix are greatly improved by incorporating another constituent to produce a composite. A composite may have a ceramic, metallic or polymeric matrix. The second phase is referred to as the reinforcement as it enhances the properties of the matrix and in most cases the reinforcement is harder, stronger and stiffer than the matrix [1]. The measured strengths of materials are several orders of magnitudes less than those calculated theoretically. Further￾more the stress at which nominally identical specimens fail is subject to a marked variability. This occurs because of the presence of inherent flaws within the material [2]. There is always a distribution in the size of the flaws and failure under load initiates at the largest of these. Griffith derived an expression relating failure stress to flaw size (a). rf ¼ KIC ya1=2 ð1Þ where rf = failure stress, KIC is the material’s fracture toughness and y a geometrical constant. As Eq. (1) shows, the larger the flaw size, the lower will be the failure stress (Fig. 8). Math_rmsAccel (G) -10 -8 -6 -4 -2 0 2 4 6 8 10 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Distance: 466.200 m 2 Accel Lat MCU 0.77 G Accel Long MCU -3.37 G Math_rmsAccel 3.44 G Speed 207 kph Math_rmsAccel (G) Min: 0.03 Max: 4.21 Mean: 1.45 Rate: 50 Hz Fig. 7. A Formula 1 car is always accelerating. G. Savage / Engineering Failure Analysis 17 (2010) 92–115 95