自分自身に信じることができるか？

Basic Concept of Improving Self-Capability

          Everyone has already agreed that stress is common problem, affecting our mental and physical health. We may think of stressful events as unpleasant ones, such as losing a job or having difficulties at home or at school. But changes for the better can also cause stress, like a new baby, a wedding, and a new house. In an ideal world, maybe we could get away from stressful situations, or change them. Too often we can't do that - but we can learn to control our response to those situations. And we can develop techniques that will reduce the effects of stress on our mental and physical health.

        Now, let's see how Physics explains about stress.

Introduction of  Stress and Strain

       Often materials are subject to forces (loads) when they are used. Mechanical engineers calculate those forces and material scientists how materials deform (elongate, compress, and twist) or break as a function of applied load, time, temperature, and other conditions.

       To compare specimens of different sizes, the load is calculated per unit area, also called normalization to the area. Force divided by area is called stress. In tension and compression tests, the relevant area is that perpendicular to the force. In shear or torsion tests, the area is perpendicular to the axis of rotation.

                            s = F/A₀ tensile or compressive stress      

                            t = F/A₀ shear stress

       There is a change in dimensions, or deformation elongation, dL as a result of a tensile or compressive stress. To enable comparison with specimens of different length, the elongation is also normalized, this time to the length L. This is called strain, e.

                           e = dL/L

Stress-Strain Behavior

• Elastic deformation. When the stress is removed, the material returns to the dimension it had before the load was applied. Valid for small strains (except the case of rubbers). Deformation is reversible, non permanent
• Plastic deformation. When the stress is removed, the material does not return to its previous dimension but there is a permanent, irreversible deformation.
• Yield point. If the stress is too large, the strain deviates from being proportional to the stress. The point at which this happens is the yield point because there the material yields, deforming permanently (plastically).
• Tensile strength. When stress continues in the plastic regime, the stress-strain passes through a maximum, called the tensile strength (sTS) , and then falls as the material starts to develop a neck and it finally breaks at the fracture point.
• Ductility. The ability to deform before braking. It is the opposite of brittleness. Ductility can be given either as percent maximum elongation e_max or maximum area reduction.
• Resilience. Capacity to absorb energy elastically. The energy per unit volume is the area under the strain-stress curve in the elastic region.
• Toughness. Ability to absorb energy up to fracture. The energy per unit volume is the total area under the strain-stress curve. It is measured by an impact test.

Stress/Strain Curve

         This diagram shows the stress / strain curve for an ‘ideal’ resin system. The curve for this resin shows high ultimate strength, high stiffness (indicated by the initial gradient) and a high strain to failure. This means that the resin is initially stiff but at the same time will not suffer from brittle failure.

        Basically, human is a special creature. Each of us has specific stress.strain curve. Definitely, after understanding about the physical approach of stress (and strain), we may conclude that stress can be handled in our "elastic deformation" region up to "yield point". If our stress exceeds our ultimate tensile strength, we can't return to our self. Some people said "mad or psychosis". Thus, stress management is needed in term of reducing and maintaining our stress not to surpass our yield point. Since, high stress is produced from high load under small surface area, enlarging this area should minimize the stress.  If the surface area means our self-capability, improving self-capability becomes a solution of reducing our stress.

         Self-capability means how we behave our self. Actually, 10% of our life happened from what we  experience directly, and 90 % remain is determined by how we react our self. Stabilizing our emotion is one way to control our behaviour, then we can decide properly our reaction of an event.