“…When simulating the installing procedure in the FEM, the 0.10 friction coefficient is adopted. The friction coefficient of 0.10–0.20 is adopted in other articles (Liu et al., 2014; Olmedo and Santiuste, 2012) according to the situation of the two contact surfaces. Figure 7.Numerical and experimental load–displacement curve during installing the pin.…”
Section: Resultsmentioning
confidence: 99%
“…It is discovered that the joint strength is influenced not only by joint geometries, joint configurations, material parameters, and loading conditions, but also by the assembly factors such as the preloads of the bolts and the fit conditions between the fastener shank and the hole (Liu et al., 2014). Among them, the fit between the pin and the hole is one of the key parameters that helps to determine the strength of pin-joined composites (Kim et al., 2012).…”
Interference-fit technology has a wide effect on the strength and fatigue life of composite structures. The damage around the hole may accelerate the structure failure. In this paper, a progressive damage model is developed to predict the response of interference-fit pin-loaded composite laminates during the installation and loading process with the ABAQUS subroutine user-define-field (USDFLD). The model takes contact at the pin–hole interface, the nonlinear shear stress–strain relationship and the property progressive damage into consideration. The loading procedure is separated into two parts: (a) installing the Hi-Lok pin. (b) Applying the tensile load. To predict progressive failure, the mixed failure criteria combining Hashin criteria and the maximum stress failure criteria, and the Camanho and Matthews degradation rules are conducted. The insertion load, stress and damage around the hole, load–displacement curve, and the bearing strength are predicted. A series of experiments have also been performed and the rationality of the model is testified. The parametric study is also made to analyze the effect of fit conditions on insertion load, damage, and load–displacement curve.
“…When simulating the installing procedure in the FEM, the 0.10 friction coefficient is adopted. The friction coefficient of 0.10–0.20 is adopted in other articles (Liu et al., 2014; Olmedo and Santiuste, 2012) according to the situation of the two contact surfaces. Figure 7.Numerical and experimental load–displacement curve during installing the pin.…”
Section: Resultsmentioning
confidence: 99%
“…It is discovered that the joint strength is influenced not only by joint geometries, joint configurations, material parameters, and loading conditions, but also by the assembly factors such as the preloads of the bolts and the fit conditions between the fastener shank and the hole (Liu et al., 2014). Among them, the fit between the pin and the hole is one of the key parameters that helps to determine the strength of pin-joined composites (Kim et al., 2012).…”
Interference-fit technology has a wide effect on the strength and fatigue life of composite structures. The damage around the hole may accelerate the structure failure. In this paper, a progressive damage model is developed to predict the response of interference-fit pin-loaded composite laminates during the installation and loading process with the ABAQUS subroutine user-define-field (USDFLD). The model takes contact at the pin–hole interface, the nonlinear shear stress–strain relationship and the property progressive damage into consideration. The loading procedure is separated into two parts: (a) installing the Hi-Lok pin. (b) Applying the tensile load. To predict progressive failure, the mixed failure criteria combining Hashin criteria and the maximum stress failure criteria, and the Camanho and Matthews degradation rules are conducted. The insertion load, stress and damage around the hole, load–displacement curve, and the bearing strength are predicted. A series of experiments have also been performed and the rationality of the model is testified. The parametric study is also made to analyze the effect of fit conditions on insertion load, damage, and load–displacement curve.
“…On the one hand, a very high force is not allowed due to the safety of the whole system. On the other hand, a tiny force is also not qualified because there should be enough preload to ensure that each step of the operation is stable, ensuring that the whole structure is stable and reliable [ 25 ].…”
The peg-in-hole task with object feature uncertain is a typical case of robotic operation in the real-world unstructured environment. It is nontrivial to realize object perception and operational decisions autonomously, under the usual visual occlusion and real-time constraints of such tasks. In this paper, a Bayesian networks-based strategy is presented in order to seamlessly combine multiple heterogeneous senses data like humans. In the proposed strategy, an interactive exploration method implemented by hybrid Monte Carlo sampling algorithms and particle filtering is designed to identify the features' estimated starting value, and the memory adjustment method and the inertial thinking method are introduced to correct the target position and shape features of the object respectively. Based on the Dempster–Shafer evidence theory (D-S theory), a fusion decision strategy is designed using probabilistic models of forces and positions, which guided the robot motion after each acquisition of the estimated features of the object. It also enables the robot to judge whether the desired operation target is achieved or the feature estimate needs to be updated. Meanwhile, the pliability model is introduced into repeatedly perform exploration, planning and execution steps to reduce interaction forces, the number of exploration. The effectiveness of the strategy is validated in simulations and in a physical robot task.
“…1–3 Although the design flexibility of composites can greatly reduce the number of parts, the decision to use assemblies instead of monolithic structures is usually motivated by manufacturing, functionality and maintaince. 4,5 Commonly the CFRP components are mainly assembled by mechanical fasteners, 6 among which the bolted interference-fit joints have been reported to improve mechanical behavior without changing joint structures. 7,8 By pressing the bolt into undersized joint-hole and applying appropriate tightening torque, the tightly coupled interface and lateral constants are achieved to benefit joints cooperatively.…”
The present research investigates the mechanism of bolt pretightening and preload relaxation in composite interference-fit joint structures under thermal effects. In view of the dissimilar material properties and the interfacial friction in such joints, the mechanical behavior of bolt and composites during assembly can be regarded as immediate preload response which is described by a linear elastic model, whereas the long-term behavior of composites during preload relaxation in service is considered as delayed response which is characterized by a viscoelastic model. The clamping forces on both sides of joints were captured to evaluate the preload balanced by the frictional behavior. The preload relaxation of joints with various interference-fit sizes and tightening torques under thermal effects were monitored for 240 hours to calibrate and validate the proposed model. The research revealed that the interference-fit size determined the level of frictional force which resulted in a difference between clamping forces at two sides of the fasteners. The preload first increases slowly with the growth of temperature, then decreases sharply when it approaches to glass transition temperature of matrix. The interference-fit joint behaves better in terms of maintaining the stability of preload than clearance-fit joints.
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