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Friction stir welding is a relatively new way to join solid materials without melting using a nonconsumable tool, which has many applications in different industries including automotive, shipbuilding, and aerospace. Destructive testing is an integral part of engineering science, which costs a lot. Reducing the number of destructive tests via numerical calculations to determine the quality of welded parts is valuable. On the other hand, advances in computer technology and embedded sensing systems in different domains have made it possible to collect a variety of data in huge volume at an unbelievable velocity, which provides an opportunity and at the same time a challenge to engineers and practitioners to utilize this rich source of information efficiently. Functional data as a rich form of structured data allows for high dimensionality modeling and analysis of the data. In this paper, we develop a fully functional linear regression model to quantify and predict the quality of the process outputs by reducing the number of destructive tests and presenting a change-point detection model to avoid using the model when a change has occurred in one of the components of the process. Important issues such as autocorrelation and correlation are taken into account in the presented model. The functional variables of the model are solved by polynomial basis function expansions. The results of the experimental tests indicate that the proposed method performs well in detecting out-of-control conditions as well as estimating the change-point location. The obtained value of the multiple correlation coefficient 0.98 and the corresponding F-value equal to 652.95 support these results. [ABSTRACT FROM AUTHOR]

Low temperature cracking is one of the main distresses observed in pavements made of hot mix asphalt mixtures. As a material property, the fracture toughness of asphalt pavements is a fundamental parameter for estimating the load bearing capacity and resistance of cracked pavements against crack growth. In this paper, the fracture toughness (KIc) of different and various compositions of asphalt mixtures is obtained experimentally, and the effects of asphalt characteristic specifications and its composition are investigated on the value of KIc. Several asphalt mixtures were prepared with three aggregate sizes, two aggregate types (limestone and siliceous), different air void percentages ranging from 3.5 to 8%, and two binders (60/70 and 85/100). Other similar work has only studied the influence of limited characteristic parameters on the low temperature fracture resistance of asphalt mixtures. Several Semi-Circular Bend (SCB) specimens subjected to three point bend loading were manufactured with different compositions and were then tested at -15°C. The experimental results showed the noticeable influence of characteristic specifications of asphalt mixtures on the value of KIc. Generally, the value of KIc decreases for those mixtures containing a smaller size of aggregates made of siliceous, with higher percentages of air voids and softer binder types. [ABSTRACT FROM AUTHOR]