Strength comparative analysis of furniture joints made of various materials

The strength comparative analysis of furniture joints made of various materials. The influence of the load on the angular deformation of the furniture joint samples made of various materials was studied. The tests were carried out for six types of furniture materials: chipboard, MDF, hardwood plywood, glued pine wood, glued oak wood and HPL and for three types of fasteners with different ways of fixing in connected elements: shape-thread, expansion-expansion and expansion-thread way of anchoring in material of boards. The joint samples were loaded with a bending moment only (without inducing transverse loadings). The maximum load capacity and load capacity at the 3° (0.052 rad) sample rotation was measured and then the stiffness coefficients were calculated. Considerable differences were found between HPL and others lignocellulosic materials. Expansion fasteners offer incredibly low joint rigidity. This was observed for all tested furniture materials, from soft (chipboard) to very hard (HPL). Expansion connectors work better in soft lignocellulosic materials than in hard materials. The main advantage of expansion fasteners, in comparison to shape-thread fasteners, is its low visibility in the joint and the technological ease of assembly. On the other hand, thread-shaped connectors offer much greater strength and stiffness of joints.

Effect of joint rigidity on structural behavior of RC buildings

Non-linear static analysis or pushover analysis is now-a –days generally preferred by many researchers to analyse the non-linear behaviour of the structure. Present study includes the effect of joint rigidity on the behaviour of the structure. A building is modeled with 5 and 10 story and designed for gravity and earthquake resistant loads by considering joint rigidity factor as 0 and 1. The analysis is done in both X and Y directions by using pushover analysis in SAP2000 software. Comparison is made between then capacity curves obtained from designed models of rigidity and non-rigidity models. From the results it is concluded that structure designed using joint rigidity has more strength when compared non-rigid joints.

Study on the correlation between knee osteoarthritis and anxiety in patients aged over 55

Introduction. Osteoarthritis, which is a cause of chronic pain and disability with manifestation in any joint, with greater frequency in the joints of the lower limbs, upper limbs, but also at the spine level , affects around 250 million people in the entire world. This condition affects around 10% of the global population (18) and has an impressive impact on people, as it is one of the first 5 causes of disability. Material and method. The objectives of the treatment made by the patients diagnosed with knee osteoarthritis were: pain reduction, increased joint amplitude, increased muscle strength, increased muscle tone, increased quality of life and reintegration into the family and social environment. In the study, there were discussed demographic data regarding the patients. In order to assess the pain parameter, the VAS scale was used, as well as WOMAC subscales. To assess the quality of life of patients with knee osteoarthritis, the QOL scale (Quality of Life) was used. Anxiety was assessed with the help of a test that comprises the evaluation of symptoms at the cognitive, behavioral and physical level. Results and discussions. The pain was evaluated on the VAS scale, having a statistically significant evolution for the evaluation moments. Also with the help of the WOMAC index, two other parameters were evaluated, namely joint rigidity and functional capacity, the results being statistically significant in the 3 evaluation moments. The patients’ anxiety was evaluated with the help of the anxiety test; the results obtained were statistically significant at the 3 evaluation moments. Conclusions. It is vital that the recovery treatment in osteoarthritis be individualized and adapted to the age group. In our group, it enabled the reduction of pain and anxiety, the increase of the functional capacity and the quality of the patients’ lives.Taking into account the fact that the most affected group in the study group was the active professional one, we can evaluate the size of the recovery and the social, family and professional integration for these patients.

A Designer-Driven Welding Simulation Analysis to Define the Best Weld Sequence for Panel Structures

Distortion is a common problem in welded panel structures, historically techniques to mitigate this problem have been developed empirically. A usual approach involves defining an intermittent weld sequence, a process that is extremely difficult to optimize given the large number of possible combinations i.e. hundreds or even thousands for multi-pass welds. Typically, plans to control weld distortion are therefore largely intuitive with welding engineers relying on their experience combined with the results of a limited number of practical tests. However, with modern computing, welding engineers can now include all the physics of welding in a simulation allowing them to cheaply and efficiently optimize a welding sequence without the need for multiple physical samples. The final welding procedure is then physically qualified based on the simulation results. In this paper, the authors present their use of computer modeling to automate the implementation of welding patterns to minimize distortion in panel lines. We describe a signature technique based on the Joint Rigidity Method where a combinatorial algorithm optimizes the welding sequence based on the panel’s resistance to angular bending i.e. the welding sequence starts at the point in the panel with the highest rigidity and moves progressively toward the lowest rigidity thereby minimizing distortion. This enables the designer to carry out an optimization of this complex weld design without relying on empirical observations.

Influence of joint rigidity on the elastic buckling load of sway and non-sway steel frames

Much work has been conducted in the past on the influence of the rigidity of structural joints on the behavior of steel frames. Buckling of a column is fundamental to the design of load bearing structures mainly when the analysis of such frames takes into account the effect of the connection flexibility. The present work deals with such an effect on the elastic buckling load of plane steel frames. The proposed model consists in the development of comprehensive approach taking into account, the effects of the joint rigidity, the elastic buckling load for both sway and non-sway frames. Only one element is required over the length of the element to model stability, which let to solve practical problem with little computational effort. Some practical formulas for determining critical load for plane steel frames are then presented. The elastic buckling load is found to be strongly affected by semi-rigid joints and reveals that the proposed model is computationally very efficient with the expressions presented being general.

The Collapse Behaviour of Cold-formed Steel Portal Frames at Elevated Temperatures

This paper describes the results of non-linear elasto-plastic implicit dynamic finite element analyses that are used to predict the collapse behaviour of cold-formed steel portal frames at elevated temperatures. The collapse behaviour of a simple rigid-jointed beam idealisation and a more accurate semi-rigid jointed shell element idealisation are compared for two different fire scenarios. For the case of the shell element idealisation, the semi-rigidity of the cold-formed steel joints is explicitly taken into account through modelling of the bolt-hole elongation stiffness. In addition, the shell element idealisation is able to capture buckling of the cold-formed steel sections in the vicinity of the joints. The shell element idealisation is validated at ambient temperature against the results of full-scale tests reported in the literature. The behaviour at elevated temperatures is then considered for both the semi-rigid jointed shell and rigid-jointed beam idealisations. The inclusion of accurate joint rigidity and geometric non-linearity (second order analysis) are shown to affect the collapse behaviour at elevated temperatures. For each fire scenario considered, the importance of base fixity in preventing an undesirable outwards collapse mechanism is demonstrated. The results demonstrate that joint rigidity and varying fire scenarios should be considered in order to allow for conservative design.