Damping capacity. Measure of the ability of a material to absorb vibration by converting mechanical energy in to heat. It is equal to the area of the elastic hysteresis loop divided by the deformation energy of a vibrating material. It can be calculated by measuring the rate of decay of vibrations induced in a material. For details see “Mechanical Properties of Polymers,” L. E. Niel son, Reinhold Publishing Corp.; “Nondestructive Testing,” W. y. Mc Gonnagle, McGraw-Hill Book Co. and “Mechanical Testing of Materials,” A. J. Fenner, Philosophical Library Inc.
阻尼性能。通过将机械能转换成热能来吸收材料振动的能力的量度。它等于弹性滞后曲线的面积除以振动材料的变形能。可以通过测量材料中引起的振动衰减率来计算。具体详情，请参阅《聚合物的机械性能》，L. E. Niel son, Reinhold Publishing Corp.;《无损检测》， W. y. Mc Gonnagle, 麦格劳·希尔出版社 ，以及《材料力学性能试验》，A. J. Fenner, Philosophical Library Inc.。
Deflection temperature. Temperature at which a plastic specimen deforms a specified amount under a specified load. It is not a direct guide to the high temperature limit of a plastic for a specified application, but rather a means for comparing the relative heat resistance of plastics. (ASTM D-648).
Deformation energy. Energy required to deform a material a specified amount. It is the area under the stress-strain diagram up to a specified strain.
Deformation under load. Measure of the ability of rigid plastics to with stand permanent deformation and the ability of nonrigid plastics to return to original shape after deformation. Standard test methods for determining both types of deformation under load are given in ASTM D-621. For rigid plastics deformation (which can be flow or flow and shrinkage) is reported as % change in height of specimen after 24 hr under a specified load. For nonrigid plastics results are reported as % change in height after 3 hr under load and recovery in the 11/2 hr period following removal of the load. Recovery is % increase in height calculated on basis of original height.
Delamination strength. Measure of the node-to-node bond strength of honeycomb core materials. It is equal to the tensile load applied to a honeycomb panel at fracture divided by its width times thickness. (ASTM C-363).
脱层强度。蜂窝芯材节点间粘结强度的测量。它等于蜂窝板在断裂处的拉伸负荷除以其宽度再乘以厚度。(ASTM C- 363)。
De Mattia flexing machine test. Method for measuring the cracking resistance (ASTM D-430) and crack growth resistance of rubber (ASTM D-813).
De Mattia弯曲机试验。橡胶的抗裂性(ASTM D-430)和抗裂纹扩展性(ASTM D-813)的测量方法。
Diamond pyramid hardness number (DPHN). Measure of the indentation hardness of a material. It is the amount of plastic deformation caused by a 136 deg pyramidal diamond indentor under a specified load. (ASTM E-92). Also known as Vickers hardness.
金刚石锥体硬度值(DPHN)。测量材料的压痕硬度。它是在指定负荷下由136度锥体金刚石压头引起的塑性变形量。(ASTM E - 92)。又称维氏硬度。
Dissipation factor. Ratio of the loss modulus to static modulus of a material under dynamic loading. It is proportional to damping capacity. An alternate term is loss tangent.
Drop ball impact test. Method for determining the energy absorption characteristics of a material subjected to shock loading. Metal ball of known weight is dropped on specimen from regularly increasing heights and height of drop, producing failure is reported. Test is used for hard metals, ceramics and plastics.
Drop weight test. Method for determining the nil-ductility transition temperature of steel. Results are reported as temperature above which specimens no longer show brittle fracture after specified shock loadings. (ASTM E-208).
Dry strength. Strength of an adhesive joint determined immediately after drying or after a period of conditioning in a specified atmosphere. (ASTM D-1144).
Ductile-to-brittle transition temperature. Indication of temperature range in which metals undergo transition from ductile to brittle behavior. It is an indication of the minimum temperature at which metals have sufficient ductility for forming. For some refractory metals ductile-to-brittle transition temperatures are well above room temperature. Ductility. Extent to which a material can sustain plastic deformation without rupture. Elongation and reduction of area are common indices of ductility.
Du Pont flexing machine test. Method for determining the cracking resistance of rubber (ASTM D-430). Rubber specimens are mounted to a fabric base and subjected to tensile and compressive flexing until failure occurs. Results are reported as a comparison of the severity of cracking in various samples, and number of cycles required to produce specified severity of cracking in the material.
Durometer hardness. Measure of the indentation hardness of plastics and rubber. It is tze extent to which a spring loaded steel indentor protrudes beyond a pressure foot into the material. Standard procedures are given in ASTM D-1706 (plastics) and ASTM D-2240 (plastics and rubber).
硬度计硬度。测量塑料和橡胶的压痕硬度。它是指弹簧负载的钢压头超过压力脚向材料中突出的程度。ASTM D-1706(塑料)和ASTM D-2240(塑料和橡胶)中均有给出其标准程序。
Dynamic creep. Creep that occurs under fluctuating load or temperature.
Dynamic ductility test. Method for determining ductility of zinc strip or sheet. A series of cups are formed by a plunger and depth of deepest nonruptured cup is reported. (ASTM B-69).
动态延展性试验。测定锌条或锌片延展性的方法。本文记录了活塞形成的一系列杯体，并对未断裂杯体的深度进行了研究。(ASTM B - 69)。
Dynamic modulus. Complex modulus of material under dynamic shear loading. It is equal to the sum of static shear modulus and loss modulus. Dynamic modulus takes into account energy dissipated as heat when material is deformed.
Dynamic modulus, effective. Indication of the vibration absorption characteristics of elastomers. It is determined in the Yerzley mechanical oscillograph test (ASTM D-945). It is not an actual physical modulus, but an extension of dynamic modulus beyond the straight line portion of the load-deformation curve.
动态模量，有效性。是指弹性体的吸振特性。它在Yerzley 机械示波器试验(ASTM D-945)中测定。它不是一个实际的物理模量，而是动态模量超过负荷-变形曲线直线部分的延伸。