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The purpose of this paper is to present a novel force sensing jig for robot-assisted drilling used to drill holes for the fastening of floating nut plates in aircraft assembly.

The paper describes the drill jig, which consists of a parallel gripper, peg-in-hole pins and a back-plate with a recess where a Polydimethylsiloxane cone is placed on top of a force sensor. As the jig approaches the part, the force sensor registers the applied force until it reaches steady state, which indicates full contact between the jig and the part. The peg-in-hole pins then lock into a pre-existing hole, which provides a mechanical reference, and the support plate provides back support during drilling.

Positional accuracy and the repeatability of the system were successfully placed within the specification for accuracy and repeatability (0.1 mm tolerance and 0.2 mm tolerance, respectively).

The drill jig can be integrated into existing robot drilling solutions and modified for specific applications. The integration of the force sensor provides data for engineers to monitor and analyze forces during drilling. The design of the force sensing drill jig is particularly suited to industrial prototype robot drilling end-effectors for small and medium manufacturers.

The key novelties of this drilling jig are in the compact assembly, modular design and inclusion of force sensing and back support features.

The effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date. The objective with the present work is to establish a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. Furthermore, the validated FE model was used to investigate the effect of stripping failure on both the rotational and load-bearing capacity of end plate connection.

The analysis was conducted on a validated numerical model of end plate connections at elevated temperatures, which predicts the mechanical behaviour and failure modes observed in the experimental tests including the bolt stripping failure. The material was modelled considering ductile damage initiation and evolution featured in ABAQUS/Standard.

This study demonstrates that thick end plates can prevent stripping failure which significantly improves the rotational capacity of the connection. This failure mode can develop readily with thin end plates; however the effect is often unrealistically mitigated through idealised experimental tests. The rotational capacity of a connection can be 5.0 times higher if stripping failure is avoided, particularly at elevated temperatures. Eurocode 3 part 1.8 does not consider the possibility of stripping failure when discussing the requirements for plastic analysis. It is concluded in the present study that by allowing for the possibility of bolt stripping, the mode of failure can often shift from end plate failure to bolt stripping, this in turn significantly reduces the connection rotational capacity.

The effect of bolt stripping failure on the ductility of steel end plate beam-column connections has received relatively little investigation to date.

To describe the prototype macadamia nut yield monitor.

In this paper, the machine vision‐based yield monitor for macadamia nut plantations is described. A summary of sensor fusion procedures is presented. Additionally, a summary of current testing progress is provided.

Using vision to count nuts has the potential to revolutionise yield monitoring for the macadamia industry. Additionally, using a vision sensor for in‐field location can provide a low cost, highly accurate method of positioning. Tractor (and nut) location can be determined accurate to 12 mm.

This project has culminated in the creation of a working prototype harvester. A commercial unit is in the design stage for operation in 2007 harvest season.

This paper describes the solution to a particular problem in the macadamia industry, with potential use in wider fields.

The purpose of this paper is to investigate the effect of geometric variables on the stress and strain distributions, as well as non‐linear deformation behaviour of aluminium alloy 2024‐T3 single‐lap bolted joints loaded in tension.

The study has been conducted by using numerical and experimental approaches. In the numerical part, 3D FE models were generated using ANSYS software for different e/d and W/d ratios in which e and W are variables but the hole diameter (d) is constant. Stress and displacement results for each case have been discussed to better explain the mode of failure. In the experimental part, e/d=3 and W/d=6 ratios were selected as constant and testing specimens were produced accordingly. The aim was to obtain baseline experimental load‐strain and load‐displacement values for selected specimen geometry coordinated with the numerical analyses.

The good agreement between the experimental and numerical analysis provided confidence in the numerical methodology used to evaluate the different geometric variables. The results showed that the single‐lap bolted plates with optimised W/d and e/d ratios could shift the failure mode from net‐tension and shear‐out to bearing failure by directing the maximum damaging stresses from the stress concentration region and shear‐out planes towards the bearing region, leading to higher failure loads.

The paper develops a FE model of single‐lap bolted joints with a non‐linear material model and investigates 3D stress analysis as well as non‐linear deformation behaviour of bolted plates; optimisation of plates' width (W) and edge distance (e) to control failure modes; and bigger W/d and e/d ratios shift net‐tension and shear‐out to bearing failure mode.

A nut bolt joint is a primary device that connects mechanical components. The vibrations cause bolted joints to self-loosen. Created by motors and engines, leading to machine failure, and there may be severe safety issues. All the safety issues and self-loosen are directly and indirectly the functions of the accuracy and precision of the fabricated nut and bolt. Recent advancements in three-dimensional (3D) printing technologies now allow for the production of intricate components. These may be used technologies such as 3D printed bolts to create fasteners. This paper aims to investigate dimensional precision, surface properties, mechanical properties and scanning electron microscope (SEM) of the component fabricated using a multi-jet 3D printer.

Multi-jet-based 3D printed nut-bolt is evaluated in this paper. More specifically, liquid polymer-based nut-bolt is fabricated in sections 1, 2 and 3 of the base plate. Five nuts and bolts are fabricated in these three sections.

Dimensional inquiry (bolt dimension, general dimensions’ density and surface roughness) and mechanical testing (shear strength of nut and bolt) were carried out throughout the study. According to the ISO 2768 requirements for the General Tolerances Grade, the nut and bolt’s dimensional examination (variation in bolt dimension, general dimensions) is within the tolerance grades. As a result, the multi-jet 3D printing (MJP)-based 3D printer described above may be used for commercial production. In terms of mechanical qualities, when the component placement moves from Sections 1 to 3, the density of the manufactured part decreases by 0.292% (percent) and the shear strength of the nut and bolt decreases by 30%. According to the SEM examination, the density of the River markings, sharp edges, holes and sharp edges increased from Sections 1 to 3, which supports the findings mentioned above.

Hence, this work enlightens the aspects causing time lag during the 3D printing in MJP. It causes variation in the dimensional deviation, surface properties and mechanical properties of the fabricated part, which needs to be explored.

Bolted joints are commonly used to connect structural members. These joints can be disassembled whenever required. Various types of washers are used between nut and the connected member to keep the joints tight. However, these joints often become loose over time under dynamic loading conditions. The purpose of this paper is to know the reasons of loosening of bolted joints and to identify the main parameters that contribute to the bolt loosening, and to verify them with previous work.

This work studies loosening of bolted joint in a test rig under varying tightening torque as well as for various types of washers used as the number of load cycles increases. Four trial runs are taken for each case considered and the average results are found out to minimize possible sources of errors. For the purpose, a specifically made test rig is used which is capable of applying harmonic load on the bolted joint by the lever action.

The study compares the loosening of bolted joint with and without washer, and also under different initial tightening conditions. This study has shown the suitability of the test rig, methodology and parameters for study of loosening in bolted joints. This study presents an indigenous test, capable of applying harmonic load on bolted joint.

The results establish that the methodology and parameters selected were appropriate for the purpose of study of loosening of bolted joints. This study has provided a base line for further work to understand the loosening of bolted joints.

The purpose of this paper is to investigate the effect of fastener geometry (protruding head and countersunk fastener) and friction coefficient on the stress distributions around the hole of the double-lap single bolted aluminium alloy joints.

3D finite element analyses of double-lap bolted 7075-T6 aluminium joints were carried out. An elastic-plastic multi-linear kinematic hardening material behaviour was assumed for the Al alloy. Contact was defined using an augmented-Langrange contact algorithm, including the friction effect. Bolt clamping force and remote axial tensile loading were applied in two load steps and their separate and combined effects on the joint behaviour were investigated for two types of fastener configurations.

It was observed that bolt clamping reduces the axial tensile stress at the hole edge by introducing a through-thickness compressive stress. This reduction in stress concentration may have a beneficial effect on the fatigue life of the joint. Second, bolt clamping reduces the bearing stress at the fastener hole by creating a frictional force between the joint plates. Results showed that the joint with protruding head fastener shows lower tensile stress concentration, and lower bearing stress, near the bolt hole of the middle plate.

Bolt clamping force reduces both the stress concentration near the hole edge and the bearing stress at the hole by creating a frictional force. Joint with a protruding head fastener may lead to higher load carrying capability and improved fatigue life. Friction coefficient affects the stress levels around the bolt hole.