Enhanced pose adjustment system for wing-box assembly in large aircraft manufacturing

Strict quality requirements in aircraft manufacturing demand high accuracy concerning pose alignments of aircraft structures. However, even though a pose adjustment system does pass the accuracy verification, the pose of the large complex structure has difficulty in smoothly and efficiently converging on the desired pose in large aircraft assembly. To solve this problem, we developed a pose adjustment system enhanced by integrating physical simulation for the wing-box assembly of a large aircraft. First, the development of the pose adjustment system, which is the base of the digital pose alignment of a large aircraft’s outer wing panel, is demonstrated. Then, the pose alignment principles of duplex and multiple assembly objects based on the best-fit strategy are successively explored. After that, the contributor analysis is conducted for nonideal pose alignment, in which the influences of thermal and gravity deformations on the pose alignment are discussed. Finally, a physical simulation-assisted pose alignment method considering multisource errors, which uses the Finite Element Analysis (FEA) to integrate temperature fluctuation and gravity field effects, is developed. Compared with a conventional digital pose adjustment system driven by the classical best-fit, the deviations of the Key Characteristic Points (KCPs) significantly decreased despite the impacts of thermal and gravity deformations. The developed pose alignment system has been applied to large aircraft wing-box assembly in Aviation Industry Corporation of China, Ltd. It provides an improved understanding of the pose alignment of large-scale complex structures.

Effect of the Position of the Boundary Rivets on the Quality of Riveted Single Strap Butt Joints

Riveting is widely used in aircraft manufacturing. The strap butt joint is often used in the aircraft’s main bearing area such as the aircraft docking area. The connection quality affects the reliability and safety of the aircraft directly. To study the effect of the rivet position on the connection quality of the strap butt joints, this paper analyzed the distribution of stress around the rivet hole at different positions by the finite element method, and then further analyzed the influence of the different rivet layouts on the connection quality of the strap butt joints by experiments. The static load tensile failure test of the joints was carried out, and the obtained tensile strength and failure mode of the strap butt joints showed that the main static tensile failure form of the single strap butt joint is that the whole rivets is sheared and the connecting sheets are separated. By changing the layout of different rivets, the connection strength can be maximized by reducing the outer row spacing (ORSD) of rivets. The results can be used for reference in the design of the riveting structure of aircraft panels.

Tensile Load Distribution Improvement of Three-Row Riveted Lap Joint Based on Different Squeezing Displacement Combinations

Many previous studies have mainly focused on the effects of riveting parameters on single-row riveted lap joints. Little attention has been paid to multi-row riveted lap joints. The outer rows of a normal multi-row riveted lap joint usually bear a larger part of the tensile load. However, none of the studies relate the phenomenon to the squeezing displacement combination of a multi-row riveted lap joint. To improve the performance of a three-row riveted lap joint, this paper aims to reveal the internal relation between tensile load distribution, structural deformation and squeezing displacement combination. Theoretical discussion, numerical simulation and an experimental test have been conducted. Four different squeezing displacement combinations have been studied. The result indicates that an appropriate squeezing displacement combination can effectively make tensile load distribution more homogeneous. Each rivet can take approximately 33% tensile load. Structural deformation magnitude can be reduced as well. Compared with the worst situation, at the region most sensitive to tensile load, the max strain value can reduce about 53.22–79.76%. A suitable squeeze displacement combination is a simple approach for the performance enhancement of a three-row riveted lap joint. It can be practically applied in aircraft manufacturing without any additional equipment or skill learning.

Evaluation of tax benefits effectiveness for certain types of activities in Ukraine

One of the stages of effective public administration of the processes of granting and applying tax benefits is to assess its effectiveness and efficiency in order to determine the feasibility of further use of tax benefits or adjustments to the policy of state support of economic agents using tax levers. The purpose of the article is to evaluate the effectiveness and efficiency of the application of tax benefits in Ukraine on the basis of methodological approaches developed by Western scientists, if the necessary information is available. The object of the study is the tax benefits introduced on a temporary basis for certain priority activities identified as requiring government support. The main sources of information for evaluation were the data of the State Tax Service of Ukraine on the amounts of tax benefits that are losses of budget revenues and other tax benefits for 2014-2019, reports of the Accounting Chamber, reports of the State Space Agency of Ukraine, data of the State Statistics Service of Ukraine, Internet resources. The first part of the article presents the results of the assessment of tax benefits for aircraft manufacturers and producers of alternative fuels obtained in 2014-2019. Based on the results of the analysis, it is concluded that although the state support for aircraft manufacturing entities provided in the form of tax incentives contributes to solving current problems, it is insufficient to achieve the targets of development of the capital-intensive industry, which requires a significant amount of financial resources, and therefore must be supplemented by other forms of the state support, the source of which are direct budget expenditures. As for the tax benefits provided to producers of alternative fuels, they are considered ineffective because they did not lead to an increase in biofuel production, so they should be supplemented by benefits aimed at stimulating its consumption: decrease in excise tax rates on biodiesel and its mixtures and motor gasolines containing bioethanol; introducing mandatory market quotas for the content of bioactive components in blended fuels, which is considered a tool for generating guaranteed demand for motor biofuels.

Predicted Torque Model in Low-Frequency-Assisted Boring (LFAB) Operations

A low-frequency-assisted boring operation is a key cutting process in the aircraft manufacturing sector when drilling deep holes to avoid chip clogging based on chip breakage and, consequently, to reduce the temperature level in the cutting process. This paper proposes a predicted force model based on a commercial control-supported chip breaking function without external vibration devices in the boring operations. The model was fitted by conventional boring measurements and was validated by vibration boring experiments with different ranges of amplitude and frequency. The average prediction error is around 10%. The use of a commercial function makes the model more attractive for the industry because there is no need for intrusive vibration sensors. The low-frequency-assisted boring (LFAB) operations foster the chip breakage. Finally, the model is generic and can be used for different cutting materials and conditions. Roughness is improved by 33% when vibration conditions are optimal, considered as a vibration amplitude of half the feed per tooth. This paper presents, as a novelty, the analysis of low-frequency vibration parameters in boring processes and their effect on chip formation and internal hole roughness. This has a practical significance for the definition of a methodology based on the torque model for the selection of conditions on other hole-making processes, cutting parameters and/or materials.

Integrated uncertainty techniques in aircraft derivative design optimization.

Aircraft manufacturing companies have to consider multiple derivatives to satisfy various market requirements. They modify or extend an existing aircraft to meet the new market demands while keeping the development time and the cost to a minimum. Many researchers have studied the derivative design process, but these research considered the baseline and the derivatives together, while using the whole set of design variables. Therefore, an efficient process that can reduce the cost and the time for the aircraft derivative design is needed. In this dissertation, Aircraft Derivative Design Optimization process (ADDOPT) was developed which obtains the global changes from the local changes in the aircraft design to develop the aircraft derivatives efficiently. The sensitivity analysis was implemented to ignore design variables that have low impact on the objective function. This avoids wasting computational effort and time on low priority variables for design requirements and objectives. Additionally, the classification of uncertainty from its characteristics and sources of uncertainty involved in the aircraft design process were suggested to consider with design optimization. Uncertainty from the fidelity of analysis tools was applied in design optimization to increase the probability of optimization results. To handle uncertainty in low fidelity analysis tools on aircraft conceptual design optimization, Reliability Based Design Optimization (RBDO) and Possibility Based Design Optimization (PBDO) methods were performed. In this research, Extended Fourier Amplitude Sensitivity Test (eFAST) method was implemented in ADDOPT for Global Sensitivity Analysis (GSA) method and Collaborative Optimization (CO) based framework with RBDO and PBDO were also used. These methods were evaluated using numerical examples. ADDOPT was carried through on the civil jet aircraft derivative design. The objective of the optimization problem was to increase cruise range while satisfying the requirement such as the number of passengers. The proposed process reduced computation effort by reducing the number of design variables and achieved the target probability of failure when considering uncertainty from low fidelity analysis tools.