J. S. Saini

A review of tool wear prediction during friction stir welding of aluminium matrix composite

Abstract Friction stir welding is the preferred joining method for aluminium matrix composites. It is a solid-state process which prevents the formation of the intermetallic precipitates responsible for degradation of mechanical properties in fusion welds of these composites. The major concern in friction stir welding is the wear of the welding tool pin. The wear is due to the prolonged contact between the tool and the harder reinforcements in the composite materials. This paper provides an overview of the effects of different parameters of friction stir welding on the tool wear. It was found that the total amount of material removed from the tool is in direct proportion to the rotational speed of the tool and the length of the weld but inversely proportional to the transverse rate. The results even demonstrate that the tool geometry also has significant influence on the wear resistance of the tool. The tool even converts itself into a self-optimized shape to minimize its wear.

Application of Taguchi method in the optimization of geometric parameters for double pin joint configurations made from glass–epoxy nanoclay laminates

In the present work, Taguchi method was used for the optimization of geometric parameters for double pin joint configurations. The orthogonal array, the signal-to-noise ratio, and analysis of variance were employed to study the effect of geometric parameters on the bearing strength of the joints. Geometric parameters, i.e. the distance from the free edge of the specimen to the diameter of the first hole (E/D) ratio, width of the specimen to the diameter of the hole (W/D) ratio, the distance between the two holes to the diameter of the hole (P/D) ratio and side width to the diameter of the hole (K/D) ratio were investigated for the serial and parallel hole configurations. The results demonstrate that the E/D ratio is the most significant parameter to increase the bearing strength in both serial and parallel pin joint configurations. Its percentage contribution is about 84.5% and 64.23% in serial and parallel pin joint configurations, respectively. Characteristic curve with Tsai–Wu failure criterion was used for the prediction of the bearing strength in the joints numerically. A good agreement was obtained between experimental results and numerical predictions.

Influence of nanoparticle fillers content on the bearing strength behavior of glass fiber-reinforced epoxy composites pin joints

The objective of the present study is to investigate and compare the strength of single pin joints made with glass fiber-reinforced epoxy laminates containing two different nanoparticles, i.e. nanoclay and nano TiO2, with bare composites. The analysis has been done both experimentally and numerically. Single-hole pin-loaded specimens were tested for their tensile strength and the distance from the free edge of the specimen to the diameter of the first hole (E/D) ratio, width of the specimen to the diameter of the holes (W/D) ratio were evaluated. The influence of these geometry parameters on the strength of the pin-loaded composites was investigated. It was found that the bearing strength of pin joints increased with the addition of nanoclay as compared to that of nano TiO2.

Investigations to increase the failure load for joints in glass epoxy composites

The present work aims to increase failure loads of pin joints through nanofillers and metal inserts. Pin joints were prepared from woven glass fiber-reinforced laminates with nanoclay as filler material along with metal inserts fitted in holes. To investigate the effect of nanoclay content, 1–5 wt.% of nanoclay was mixed in epoxy. The increase in tensile strength up to 3 wt.% of nanoclay was observed which was due to increase in the specific surface area of the nanocomposite material. Dispersed nanoclay filler particles act as mechanical interlocking between fiber and epoxy matrix which creates a high friction coefficient. The optimal nanoclay content of 3 wt.% was finally used to prepare nanocomposite laminates. The geometric parameters, i.e. edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio were varied from 2 to 5 and 3 to 6, respectively. Progressive damage analysis along with Hashin failure criteria was performed to predict failure loads and failure modes in pin joints, numerically. Metal inserts reduced the stress concentration around the hole and redistributed stresses at the pin/hole interface, which eventually increased the ultimate failure load of the joint.

To study the contribution of different geometric parameters on the failure load for multi holes pin joints prepared from glass/epoxy nanoclay laminates

The present work aims to analyze the strength and failure modes for the multi holes pin joint configurations made from unidirectional glass/epoxy nanoclay laminates. The geometric parameters, i.e. the distance from the free edge of the specimen to the diameter of the first two holes (E/D) ratio, the distance between two holes along the length of the specimen to the diameter of the hole (F/D) ratio, the distance between the two holes along the width of the specimen to the diameter of the hole (P/D) ratio and side width to diameter (S/D) ratio were studied for their effect on strength and failure modes of the joint. Design of experiment with Taguchi method was used for the optimization of different geometric parameters. Analysis of variance was applied to determine the influence of individual geometric parameter on the strength of the joint. The results demonstrate that the E/D and F/D ratios are the most significant parameters to increase the strength of multi holes pin joint configurations. Their percentage contributions were about 62% to 65% and 23% to 26%, respectively. Thereafter, the characteristic curve method along with Tsai–Wu failure criteria was applied to compare the numerical and experimental predictions.

Tool Path Generation for Free-Form Surfaces Using B-Spline Surface

Tool path generation is an important step for the machining of the free-form surfaces. The accuracy of machining free-form surfaces greatly depends upon the tool path. A number of algorithms had been proposed by different researchers for the accurate and efficient tool path generation for the machining of the free-form surfaces. The present study is focused on implementation of one of the algorithm that generates tool paths for free-form surfaces based on the accuracy of a desired manufactured part. This algorithm includes two components. First is the forward-step function that determines the maximum distance between two cutter contact points with a given tolerance. The second component is the side-step function which determines the maximum distance between two adjacent tool paths with a given scallop height. These functions are independent of the surface type and are applicable to all continuous parametric surfaces that are twice differentiable. This algorithm reduces cutter contact (CC) points while keeping the given tolerance and scallop height in the tool paths. The algorithm is implemented using the B-spline surface. It is then used to machine a wax component which is compared with the desired surface.