Ride quality

Other qualities sought in a tire include ride quality, cornering ability, traction characteristics on both dry and slippery roads, tire noise, life, and cost. Addressing these qualities often opposes the objective of lower rolling resistance. 

Customer Initial cost Operational and maintenance costs Quality Range (between refueling) and refueling convenience Passenger/cargo space Performance (acceleration, speed, ride quality, acceptably low levels of noise, vibration, and harshness) Safety... 

Mechanical Characterization of Sulfur-Asphalt. The serviceable life of a pavement comes to an end when the distress it suffers from traffic and climatic stresses reduces significantly either the structural capacity or riding quality of the pavement below an acceptable minimum. Consequently, the material properties of most interest to pavement designers are those which permit the prediction of the various forms of distress—resilient modulus, fatigue, creep, time-temperature shift, rutting parameters, and thermal coefficient of expansion. These material properties are determined from resilient modulus tests, flexure fatigue tests, creep tests, permanent deformation tests, and thermal expansion tests. 

One such use was made by General Motors in the structural design of its Cadillac Seville. The use of NASTRAN improved the car s ride quality within weight limits and saved considerable development time. GM s successful application of NASTRAN to automotive structural design has since inspired the company to extend computer analysis to the entire GM line. 

Factors such as the rapid increase of traffic volume and axial loading, the higher demands of users for better and constant ride quality and the users disturbance during maintenance works made the need for improvement of bitumen properties and consequently of the bituminous works imperative. 

The environmental factors that are considered by the methodology to affect the performance of new pavement are the subgrade swelling and frost heave. Either of these factors, or both, can lead to a significant loss of serviceability or ride quality during the analysis period. 

Transverse joints should be made in fresh concrete (only in the case of pavements not requiring a very high level of riding quality). 

The functions of steel reinforcement in rigid pavements are primarily to counteract the temperature- and moisture-induced stresses, to reduce the number of transverse joints (jointed reinforced slabs) or eliminate the transverse joints (continuously reinforced slabs), to minimise future maintenance cost and, to a certain extent, to reduce the thickness of the slab. The reduction or elimination of transverse joints has a direct impact on the improvement of the riding quality offered. Some countries like the United Kingdom recommend to use, almost exclusively, continuously reinforced slabs on new constructions, hence the absence of transverse joints, with an thin (30 mm) or thick (100 mm) asphalt layer on top. 

Functional evaluation considers the surface characteristics of a pavement and is user related. Surface characteristics include longitudinal evenness (smoothness), skid resistance, rutting, cracking or any other surface distress that affects riding quality and safety. Functional evaluation is used to decide whether the pavement needs to be maintained, rehabilitated or reconstructed essentially, the necessity for intervention and its type is decided. 

The first expression of the functional evaluation of the pavement was related to the rideability or acceptability of the pavement by road users. The determination of the ride quality was carried out by a group of people who drove over various pavement sections of excellent to unacceptable quality level and then rated the pavement sections on a scale of 0 to 5. Such pavements were those constructed during the AASHTO experiment (AASHTO 1962 Carey and Irick 1960). 

Apart from the term unevenness, usually used by EN standards, the term roughness is also used, usually by US standards. According to ASTM E 867 (2012), travelled surface roughness is the deviations of a surface from a true planar surface with characteristic dimensions that affect vehicle dynamics, ride quality, dynamic loads and drainage, for example, longitudinal profile, transverse profile and cross slop. 

The pavement surface condition is assessed in terms of riding quality, rut depth, texture depth and surface cracking, and, if hot rolled asphalt surfacing, fretting. 

The assessment of ride quality or profile unevenness is carried out using three Enhanced Longitudinal Profile Variance values that indicate the level of profile unevenness within wavelength ranges less than or equal to 3, 10 and 30 m. 

Threshold values for ride quality per category of road are given in Table 16.12, and the threshold values for rut depth and texture depth for all road categories are given in Table 16.13. 

Table 16.12 Ride quality criteria of all types of construction for TRACS measurements (enhanced longitudinal profile variance [E-LPV], 100 m lengths)...

A quarter car model is used to illustrate MORA. This model is a standard vehicle dynamics model used in automotive engineering for ride quality evaluation [20] and it is depicted in Fig. 2.5. Though it is already a relatively small model (two DOF, requiring four state variables), it still serves the purpose of illustrating the proposed ideas, as well as showing that even a relatively small model may not be proper. 

The second scenario was a shaker table scenario. This scenario might be of interest when studying, e.g., the suspension characteristics and ride quality of a vehicle. In this scenario the tires were removed from the model, and a sinusoidal sweeping displacement was applied to all four wheel hubs. The output of interest was the vertical position of the chassis. 

Aeroelastic and vibration control technology allows flight vehicles to operate beyond the traditional flutter boundaries, improves ride qualities, and minimizes vibration fatigue damage. Conventional active flutter and vibration control technology relies on the use of aerodynamic control surfaces operated by servo-hydraulic actuators. In this conventional configuration, the... 

The standards from the fourth group contain mechanical data for safety limitations. EN 115-1-hA1 comprises all types of hazards, allowable distances, speed and load limitations etc. ISO 18738-2 provides readers with information about ride quality of escalators and moving walks, it focused mainly on vibration and noise. 

It is not uncommon to see a network of cracks in rail cross sections, and multiple cracks may shield each other and reduce crack propagation rate. The cracks may also branch. If the crack branches upwards and reaches the surface then a piece may be separated from the rail and lost as wear debris. The resulting spall or pit leads to surface roughness and deterioration in ride quality. If however, the crack branches downwards and continues to propagate then potentially a more dangerous situation develops, and the rail may break. Since, the propagation due to contact stresses is expected to slow down as the crack extends there must be... 

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