poor stand establishment of canola (brassica napus l.) under flatland mechanized planting and crust-forming soil is a major problem for farmers in central iran. previous research there showed that irrigated cotton emergence on crust-forming soils under flatland planting can be significantly improved using a double-disk planter with zero-pressure press wheel tires and no crust-breaking. in that ...

This paper presents a new sectional flexibility factor to simulate the reduction of the stiffness of a single-edge open cracked beam. The structural model for crack of the beam is considered as a rotational spring which is related to the ratio of crack depth to the beam height, a/h. The mathematical model of this single-edge open crack beam is considered as an Euler-Bernoulli beam. The modified...

In this article, the size effect on the dynamic behavior of a simply supported multi-cracked microbeam is studied based on the Modified Couple Stress Theory (MCST).  At first, based on MCST, the equivalent torsional stiffness spring for every open edge crack at its location is calculated; in this regard, the Stress Intensity Factor (SIF) is al...

in this paper, buckling of simply supported column with an edge crack is investigated numerically and analytically. four different scenarios of damage severities are applied to a column, open crack assumption and the effect of closing crack in stability of the column which depends on position and size of cracks, are numerically compared. crack surfaces contact is modeled with gap element using ...

in this paper, in order to analyze the transverse vibration of a uniform bernoulli-euler beam containing one single edge crack, a new continuous model is proposed for the cracked section. to this end, by using the fracture mechanics, the crack is modeled as a continuous disturbance in the stress and strain fields. by applying the hamilton’s principle, the equation of motion and the correspondin...

In this paper, buckling of simply supported column with an edge crack is investigated numerically and analytically. Four different scenarios of damage severities are applied to a column, open crack assumption and the effect of closing crack in stability of the column which depends on position and size of cracks, are numerically compared. Crack surfaces contact is modeled with GAP element using ...

In this paper, edge crack problems under mechanical loads have been analysed using extended finite element method (XFEM) as it has proved to be a competent method for handling problems with discontinuities. The XFEM provides a versatile technique to model discontinuities in the solution domain without re-meshing or conformal mesh. The stress intensity factors (SIF) have been calculated by domai...

The initial stage of fretting fatigue crack growth is significantly influenced by tangential force induced by fretting action along the contact surface where a mixed-mode crack growth is involved. Fretting crack behavior of aluminum alloy 2024 was studied, taking into account the problem of contact asperities. Finite element was used for the determination of the stress field near the contact su...

The stress distribution on the tip of the cracks and the stress intensity factor on them are the main courses in the fracture mechanic. The stress intensity factor of the cracks with the different load exited and the different geometry are listed in the tables of the standard books. In all of them, the cracks are located in the central point of the plates. In the uniform edge loaded case, the c...

An evolutionary approach for fatigue crack detection in cantilever type of machine structure is investigated in this paper. Fault like fatigue crack detection has received a great attention in recent years. A surface transverse open edge crack is considered for this study. Actual fatigue crack may behave like a non-linear due to opening and closing under vibration. But due to small level of vib...